Monitoring device for managing state of reflection plate, control method, and program

Abstract

Provided is a monitoring device that uses a reflection plate comprised of a plurality of reflection elements to monitor a reflection device that reflects radio waves transmitted from a base station. The monitoring device monitors the state of the reflection elements constituting the reflection plate, and, when a defective element that is a reflection element not operating normally has been detected by a monitoring means, notifies the base station of detection information of the defective element.

Description

Monitoring device, control method, and program for managing the status of a reflector

[0001] The present invention relates to a technique for managing the state of a reflector.

[0002] In mobile communications, wireless communication services are provided to terminals located in positions where they can receive radio waves transmitted from base stations. Therefore, it is important that the radio waves transmitted by the base station reach the terminal's location appropriately. In particular, in recent wireless communication environments that tend to use high-frequency bands, wireless quality is easily degraded due to the influence of obstructions, etc., so the use of reflectors that reflect radio waves between the base station and the terminal has been considered. While reflectors can change the direction in which radio waves are reflected by changing their physical orientation, metasurface reflectors can reflect radio waves in various directions through electrical control without changing their physical orientation. Non-Patent Document 1 describes a technology in which a base station controls the radio wave reflection pattern of a reflector by transmitting control information to a reflector control device.

[0003] Wu, Qingqing and Rui Zhang, “Intelligent reflecting surface enhanced wireless network: Joint active and passive beamforming design”, 2018 IEEE Global Communication Conference (GLOBECOM), 2018

[0004] The present invention provides a technique for efficiently detecting defective elements in a wireless communication system that uses a reflector.

[0005] A monitoring device according to one aspect of the present invention is a monitoring device that monitors a reflecting device that reflects radio waves transmitted from a base station using a reflecting plate composed of a plurality of reflecting elements, and has a monitoring means that monitors the state of the reflecting elements that compose the reflecting plate, and a notification means that, when the monitoring means detects a defective element, which is a reflecting element that is not operating normally, notifies the base station of the detection information of the defective element.

[0006] According to the present invention, it is possible to efficiently detect defective elements in a wireless communication system that uses a reflector.

[0007] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals.

[0008] The accompanying drawings are included in and form part of the specification, illustrate embodiments of the present invention, and together with the description are used to explain the principles of the present invention. A diagram showing an example of the configuration of a wireless communication system. A diagram showing an example of reflective element setting. A diagram showing an example of reflective element setting. A diagram showing an example of reflective element setting. A diagram showing an example of reflective element setting. A diagram showing an example of hardware configuration of a base station and a control device. A diagram showing an example of the functional configuration of a control device. A diagram showing an example of the functional configuration of a base station. A diagram showing a process flow when a control device reports information about a defective element to a base station, and the base station notifies the control device of the reflective element setting. A diagram showing a process flow when a control device performs monitoring processing and reporting processing for a defective element. A diagram showing a process flow when a control device stops reporting a defective element or stops control of a reflecting device.

[0009] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any desired manner. Furthermore, the same reference numerals are used to designate identical or similar components, and redundant descriptions will be omitted.

[0010] (System Configuration) FIG. 1 shows an example of the configuration of a wireless communication system according to this embodiment. The wireless communication system is, for example, a cellular communication system conforming to the cellular communication standard of the Third Generation Partnership Project (3GPP (registered trademark)). However, this is not limited to this, and the following discussion can be applied to a wireless communication system conforming to any wireless communication standard. The wireless communication system includes, for example, base stations 101, 102, and 103, terminals 111 and 112, reflecting devices 121 and 122, and control devices 131 and 132. In this embodiment, the base stations 101 to 103 may be referred to as base stations 100 without distinction. Furthermore, the terminals 111 and 112 may be referred to as terminals 110 without distinction, the reflecting devices 121 and 122 may be referred to as reflecting devices 120 without distinction, and the control devices 131 and 132 may be referred to as control devices 130 without distinction. Here, the base station 103 is assumed to be a base station that configures a cell 143 with greater coverage than the other base stations. For example, the base station 103 can communicate with other communication devices such as the terminal 110 over an area with a radius of several hundred meters to several tens of kilometers centered on the base station 103. The base station 103 may be called a macrocell base station. On the other hand, the base stations 101 and 102 configure cells 141 and 142, respectively, which have smaller coverage than the base station 103. The base stations 101 and 102 may be called small cell base stations. In this embodiment, the terminals 111 and 112 communicate with the base stations 101 and 102, respectively. The terminal 110 may be called User Equipment (UE).

[0011] Here, for example, suppose there is a shield or the like between the base station 101 and the terminal 111, and radio waves transmitted from the base station 101 are not received with sufficient strength by the terminal 111. In this case, there is a possibility that radio waves transmitted from the terminal 111 are also not received with sufficient strength by the base station 101. A location within the cell of the base station 100 where radio waves transmitted from the base station 100 are not received with sufficient strength is sometimes called a blind zone. In particular, the possibility of a blind zone occurring increases when radio waves in a high frequency band are used. In such a situation, by placing a reflecting device 121 in a position where radio waves can be transmitted and received with sufficient strength to both the base station 101 and the terminal 111, the reflecting device 121 can relay communication between the base station 101 and the terminal 111. The reflecting device 121 reflects radio waves transmitted from the base station 101 in a predetermined reflection pattern. The reflecting device 121 also reflects radio waves transmitted from the terminal 111 in a predetermined reflection pattern. By appropriately setting the reflection pattern of the reflector 121, radio waves transmitted from the base station 101 can be reflected toward the terminal 111, and radio waves transmitted from the terminal 111 can be reflected toward the base station 101. As a result, radio waves transmitted from the base station 101 can be received by the terminal 111 with sufficient strength, and radio waves transmitted from the terminal 111 can be received by the base station 101 with sufficient strength. Here, the reflection pattern is a pattern that indicates the gain of the reflector for each direction, and is determined by the reflection phase set in the reflecting elements that constitute the reflector of the reflector 120. For example, there is a pattern in which radio waves incident from a specific incident direction are hardly attenuated, and radio waves incident from another incident direction are attenuated to almost zero. Furthermore, radio waves emitted in a specific direction are emitted with high power, and radio waves are hardly emitted in other directions. In this way, the reflection pattern is expressed by a combination of patterns that indicate the gain of the incident and emitted waves, respectively.

[0012] The control device 131 is connected to the reflecting device 121 and controls the reflection pattern of the reflecting device 121. The control device 131 and the reflecting device 121 may be implemented as an integrated unit or as separate units. The control device 131 may control the reflecting device 121 so as to form a predetermined fixed reflection pattern. Furthermore, when the control device 131 and the base station 101 are wirelessly connected, the base station 101 can remotely control the reflecting device 121 via the control device 131. Furthermore, when the base station 103 and the control device 131 are wirelessly connected, the base station 103 can remotely control the reflecting device 121 via the control device 131. For example, the base station 103 is assumed to include within its cell 143 a wide area including the cells 141 and 142 of the base stations 101 and 102, respectively, and the base stations 101 to 103 are assumed to belong to the same network domain and to be able to cooperate with each other. In this case, when the base station 101 and the terminal 111 are wirelessly connected via the reflecting device 121 and the control device 131 is wirelessly connected to the base station 103, the reflecting device 121, which relays between the base station 101 and the terminal 111, can be controlled by the base station 103 via the control device 131. In this way, a base station covering a wide area can centrally control the reflecting devices via the control device, thereby enabling the entire wireless communication system to be managed in an integrated manner and making it possible to eliminate more blind zones.

[0013] The same discussion can be applied to communication between the base station 102 and the terminal 112. For example, when radio waves of sufficient strength cannot be transmitted and received between them due to obstructions or the like, a reflecting device 122 can be installed and the control device 132 can control the reflecting device 122 to enable communication between the base station 102 and the terminal 112. The configuration in FIG. 1 is merely an example. For example, the number of reflecting devices relaying communication between the base station 100 and the terminal 110 may be one or two or more. Also, a large number of terminals may be connected to the base station 100. In this case, some terminals may communicate directly with the base station 100 without going through the reflecting device 120, and other terminals may communicate with the base station 100 via the reflecting device 120.

[0014] The reflecting device 120 includes a reflector that reflects radio waves incident on the reflecting device 120 in a predetermined direction and is configured to be able to change the reflection pattern of the reflector. For example, the reflecting device 120 changes the reflection direction of radio waves transmitted from the base station 100 or the terminal 110 by physically controlling the attitude of the reflector so that it faces a desired direction. The reflecting device 120 may also be configured to include a reflector using an intelligent reflecting surface (IRS) that uses a metasurface. The IRS may be composed of, for example, multiple reflecting elements, and the reflection phase of each reflecting element may be controlled to form a reflection pattern. As an example, a metasurface reflecting device using a liquid crystal may have a reflector with a liquid crystal layer provided between the reflecting element and a ground (ground plate). In this reflecting device, the reflecting element is used as an electrode, and a voltage is applied to the reflecting element. By changing the voltage applied to the reflecting element, the electrical characteristics (dielectric constant) of the liquid crystal change, and the reflection phase of the reflecting element changes in response to the change in the dielectric constant of the liquid crystal. In this way, the reflection phase of the reflecting element can be precisely controlled by changing the voltage applied to the reflecting element. Therefore, by adjusting the voltage applied to each of the reflecting elements that make up the reflecting plate, the reflecting plate can be controlled to form a desired reflection pattern. In this way, by using a metasurface, the reflection direction of radio waves can be changed without physically changing the orientation or posture of the reflecting device. The reflecting device 120 may also have other reflection mechanisms. For example, the reflecting device 120 may include an IRS reflecting plate using a diode. In a metasurface reflecting plate using a diode, the reflecting element and the circuit element are connected by a diode. When a voltage is applied to the diode, a current flows in the circuit, resulting in a change in the reflection phase of the reflecting element. In this way, the reflection pattern of the reflecting device 120 can be controlled by the voltage applied to the diode. In this embodiment, the reflecting device 120 is described as having a metasurface reflecting plate using a liquid crystal.

[0015] The control device 130 controls the reflection pattern of the reflecting device 120. For example, the control device 130 has setting information (reflecting element setting) that specifies the reflection phase to be set for each reflecting element. The control device 130 controls the reflection phase of each reflecting element according to this reflecting element setting. As an example, the reflecting element setting includes information for identifying each reflecting element and information for specifying the reflection phase to be set for each reflecting element. The information for identifying each reflecting element may be the position of each reflecting element on the reflector or an identifier of the reflecting element. Furthermore, the information for specifying the reflection phase of each reflecting element may be the absolute value of the reflection phase or a relative value with respect to a reference value of the reflection phase. The information included in the reflecting element setting is not limited to these, and the information for identifying each reflecting element and the information for specifying the reflection phase of each reflecting element are not limited to these. A reflecting element setting may exist for each reflection pattern formed by the reflecting device 120. For example, if a pattern ID is assigned to each reflection pattern as an identifier that uniquely identifies the reflection pattern, the control device 130 may set the reflection phase of each reflecting element on the reflector according to the reflecting element setting associated with each pattern ID.

[0016] The reflection pattern set in the reflecting device 120 may be notified to the control device 130 by the base station 100. For example, the base station 100 generates a reflecting element setting for each reflecting element constituting the reflector of the reflecting device 120 and notifies the control device 130. Note that a device other than the base station 100 may generate the reflecting element setting, or a device other than the base station 100 may notify the control device 130 of the reflecting element setting. If the reflection pattern and the reflecting element setting are associated in advance and shared between the base station 100 and the control device 130, the control device 130 can control the reflection pattern of the reflecting device 120 by notifying the control device 130 of a pattern ID from the base station 100. In other words, the control device 130 sets the reflection phase of each reflecting element of the reflecting device 120 according to the reflecting element setting associated with the notified pattern ID. Note that the information notified by the base station 100 to the control device 130 is not limited to the pattern ID. For example, the reflecting element setting itself may be notified.

[0017] If a defective element is present among the reflective elements constituting the reflector, the desired reflection pattern may not be formed. In this embodiment, a reflective element that does not operate normally is referred to as a defective element. For example, a defective element may be formed due to damage to the reflective element itself, deterioration of the electrical characteristics of the liquid crystal constituting the reflector, or a failure in the circuit that applies voltage to the reflective element. Note that the causes of defective elements are not limited to those described above. For example, even if a predetermined voltage according to the reflective element settings is applied to a reflective element with deteriorated electrical characteristics, the liquid crystal may not have the desired dielectric constant, resulting in an undesired reflection phase of the reflective element. If the reflection phase of the defective element differs from the desired reflection phase, the desired reflection pattern will not be formed as the reflection pattern of the reflector device 120. In this way, if the desired reflection pattern is not formed due to the presence of a defective element, for example, radio waves transmitted by the base station 100 and reflected by the reflector device 120 may not be received with sufficient strength by the terminal 110. If sufficient power is not received, blind zones will not be eliminated, resulting in degraded area coverage. Furthermore, if a peak of the reflection pattern is formed in a direction different from the desired direction, the accuracy of azimuth estimation and beam training may be reduced.

[0018] To detect the presence of a defective element, for example, the terminal 110 may measure the reception strength of radio waves transmitted by the base station 100 and reflected by the reflecting device 120. In this case, it is necessary to dispatch an operator or the like to the site to perform periodic measurements, etc. In addition, performance degradation of the reflector of the reflecting device 120 may be detected by receiving a report on the radio wave reception status from the user of the terminal 110. In consideration of such a situation, this embodiment provides a method in which the control device 130 connected to the reflecting device 120 monitors the presence of a defective element and autonomously reports it to the base station 100. This makes it possible to detect the presence of a defective element early and efficiently maintain and operate the reflecting device 120 without dispatching an operator or the like to the site. The following describes the processing related to the detection and reporting of defective elements in this embodiment.

[0019] (Detection and Reporting of Defective Elements) The control device 130 monitors the status of each reflective element in the reflector of the reflecting device 120. As an example, to determine whether each reflective element is operating normally, the control device 130 periodically applies a predetermined voltage to each reflective element and determines whether the liquid crystal of each reflective element is controlled to a desired dielectric constant. For example, each reflective element may have an electrode for measuring the dielectric constant of the liquid crystal. Note that the method for measuring the dielectric constant of the reflective element is not limited to this. For example, the control device 130 calculates the difference between the measured dielectric constant of the liquid crystal and a predetermined reference value, and if the difference exceeds a threshold, determines that the reflective element is not operating normally. Note that the method for determining whether each reflective element is operating normally is not limited to this, and an appropriate method may be used depending on the configuration of the reflector of each reflecting device 120. The control device 130 periodically executes this determination process for each reflective element to monitor the status of each reflective element.

[0020] The control device 130 reports the status of each reflective element on the reflector of the reflector device 120 to the base station 100. For example, the control device 130 reports detection information of detected defective elements to the base station 100. As an example, the detection information is identification information that can identify the defective element. The identification information can be the position of the defective element on the reflector. For example, if the reflector is composed of M rows and N columns of reflective elements, the position of the defective element can be identified by a combination of the row number and column number. Furthermore, if each reflective element is assigned an identifier that can uniquely identify the reflective element on the reflector, the control device 130 can identify the defective element using the identifier. Note that the method for identifying the defective element is not limited to these. Furthermore, the control device 130 may report the number of detected defective elements and the defect rate to the base station 100 as detection information. Note that in this embodiment, the ratio of defective elements to the reflective elements that make up the reflector is referred to as the defect rate. By using the number of defective elements and the defect rate, the control device 130 can report the status of the reflecting elements in the reflecting device 120 to the base station 100 with a smaller amount of information than when notifying information about individual defective elements.

[0021] (Changing the Reflection Phase) When the base station 100 receives a report of information about defective elements from the control device 130, the base station 100 can change the reflection phase set for each reflecting element based on the reported information about the defective elements. For example, if reflecting element settings that anticipate the occurrence of defective elements are shared in advance between the base station 100 and the control device 130, the base station 100 can notify the control device 130 of information that identifies this reflecting element setting. The control device 130 can change the reflection phase of each reflecting element according to the notified information.

[0022] The base station 100 may generate a new reflecting element setting that takes into account the influence of the reported defective element. Note that a device other than the base station 100 may generate the reflecting element setting. For example, the control device 130 may generate the reflecting element setting. As an example, the base station 100 may generate a new reflecting element setting using a genetic algorithm. An example of a method for generating a reflecting element setting using a genetic algorithm is described below. First, if a reflector is composed of M rows and N columns of reflecting elements and the reflection phase of each reflecting element is expressed by R bits, a matrix with M×N×R rows and P columns is generated in which 0s or 1s are randomly assigned as each element of the matrix. P is an arbitrary integer. Here, the value of an element in the matrix corresponding to a defective element is set to zero. Next, an objective function is calculated for each row, with the components of each row corresponding to the reflection phase of each reflecting element. For example, the objective function is the transmission power in the direction in which a peak is formed in the desired reflection pattern. Once the calculation of the objective function for all rows is completed, the rows are rearranged based on the value of the objective function. For example, the rows are rearranged in descending order of transmission power in the objective function. Then, the top 50% of the objective functions are retained, and the remaining 50% are discarded. The remaining top 50% are used to generate new rows so that there are again P columns. The generated matrix is ​​used to calculate the objective function for each row. This process is repeated until the convergence condition is met, and the surviving components are selected as the reflection phases of each reflection element. In this way, by using a genetic algorithm, it is possible to generate reflection element settings that form a desired reflection pattern even in a situation where defective elements are present.

[0023] The method for generating the reflecting element setting is not limited to the method using a genetic algorithm. For example, the base station 100 may generate a new reflecting element setting by adding a predetermined common phase to the reflection phase of each reflecting element in the current reflecting element setting. For example, the impact of a reflecting element not operating normally may be caused by a difference between the phase to be set for that reflecting element in the reflecting element setting and the reflection phase of the actual defective element. Assuming that the reflection phase of the actual defective element is zero, adding a common phase to the reflection phases of all reflecting elements so that the reflection phase of the defective element in the reflecting element setting becomes zero can reduce the impact of the defective element while maintaining the current reflection pattern. In this case, the base station 100 may notify the control device 130 of the amount of change in the common reflection phase to be added to the reflection phase of each current reflecting element. When the reflecting element setting generated by the base station 100 is notified to the control device 130, the control device 130 controls the reflection phase of each reflecting element of the reflecting device 120 according to the reflecting element setting.

[0024] (Notification of Reflection Phase) When the base station 100 notifies the control device 130 of the reflecting element settings it has generated, the amount of information to be notified may be enormous. For example, assuming that a 100-wavelength reflector is composed of approximately 40,000 reflecting elements, information on the reflection phase to be set for each of the 40,000 reflecting elements is notified. Furthermore, the reflecting element settings may contain redundant information. A method for efficiently notifying the reflection phase in this embodiment will be described using an example of reflecting element settings shown in FIGS. 2A to 2D. In FIG. 2A, the base station 100 extracts differences between the reflecting element settings before and after the change based on the generated reflecting element settings and the current reflecting element settings of the reflecting device 120, and notifies the control device 130 of only the settings for the reflecting elements with differences. For example, assuming that the number of reflecting elements with differences is D and the reflector is composed of M rows and N columns of reflecting elements, the amount of information to be notified from the base station 100 to the control device 130 can be reduced to D / (M×N) by notifying only the settings of the reflecting elements with differences. In FIG. 2B , if the reflection phases for some of the reflecting elements in the generated reflecting element settings are a common value, the base station 100 aggregates the reflecting elements to which this common value is set and notifies the control device 130. For example, the base station 100 associates the common reflection phase with information identifying the reflecting elements to which this reflection phase is set and notifies the control device 130. This reduces the amount of reflection phase information corresponding to the number of aggregated reflecting elements. In FIG. 2C , if the reflection phases to be set for some of the reflecting elements in the generated reflecting element information have a common regularity, the base station 100 notifies the control device 130 of this common regularity. For example, the base station 100 associates information identifying the common regularity with information identifying the reflecting element to be set and notifies the control device 130. An example of a common regularity is to set reflection phases for reflecting elements within a predetermined range, starting from a defective element, by increasing the phase by the same amount in order. FIG. 2D shows a rule for setting the reflection phase of each reflecting element by increments of 10 degrees in the Y direction. Note that base station 100 may notify control device 130 of information specifying which of the above-mentioned methods to use to notify the reflecting element setting.For example, an identifier may be assigned to each notification method, and the identifier may be notified from the base station 100 to the control device 130, or from the control device 130 to the base station 100, during connection processing between the base station 100 and the control device 130. Also, the base station 100 may notify the control device 130 of the notification method to be used each time it notifies the control device 130 of reflecting element information. Note that the base station 100 may generate a new reflecting element setting for each reflection pattern and notify the control device 130 of the setting.

[0025] (Control of Monitoring and Reporting by the Base Station) The control device 130 connected to the reflection device 120 monitors the presence of defective elements in the reflection device 120 and autonomously reports to the base station 100, enabling efficient maintenance and operation of the reflection device 120. On the other hand, if defective elements are frequently reported from multiple control devices 130, the amount of information required for the report increases, which may affect data communication. For example, if the report of defective elements is performed using a control channel or part of the header on the wireless frame, like other control information, the report of the defective element may put pressure on the transmission of other control information, resulting in delays in data communication. Furthermore, if the defect rate is low, the impact of defective elements on the reflection pattern may be small. In this embodiment, as an example, a method is provided in which the base station 100 controls the monitoring of defective elements and the reporting of information about defective elements performed by each control station 130.

[0026] For example, the base station 100 generates monitoring settings for controlling the monitoring of defective elements performed by the control device 130 and notifies the control device 130 of the monitoring settings. As an example, if the control device 130 is to periodically determine the state of each reflective element and report the determination results, the base station 100 notifies the control device 130 of monitoring settings including the period for which the determination is to be made. Also, for example, if the control device 130 is to perform monitoring processing semi-permanently, the base station 100 notifies the control device 130 of monitoring settings including the period for which the determination is to be made and the period for which the determination is to be made during that period. Note that the base station 100 may request that the control device 130 perform the determination at a time instructed by the base station 100. In this case, the base station 100 may notify the control device 130 of monitoring settings including the time for which the determination is to be made. Furthermore, the base station 100 may notify the control device 130 of monitoring settings including a condition for changing the period for which the determination is to be made. As an example, the period for which the determination is to be made may be changed on the condition that the defect rate exceeds a threshold. In this case, the base station 100 notifies the control processing device 130 of the monitoring settings including the defect rate threshold as a condition for changing the determination period and the periods for making the determination before and after the condition is satisfied.

[0027] The base station 100 may also generate a reporting setting for controlling the reporting of information about defective elements executed by the control device 130 and notify the control device 130 of the generated setting. As an example, when controlling the control device 130 to report when a predetermined condition is met, the base station 100 notifies the control device 130 of a reporting setting including the condition. For example, when a condition is set to a defect rate exceeding a threshold, the base station 100 notifies the control device 130 of a reporting setting including a defect rate threshold. Furthermore, when causing the control device 130 to report again after the defect rate exceeds a threshold, the reporting setting may include multiple defect rate thresholds. For example, if the first to third thresholds are set to 0.1, 0.2, and 0.3, respectively, the control device 130 receiving the reporting setting executes a report to the base station 100 when the defect rate exceeds any of 0.1, 0.2, and 0.3. The control device 130 may report to the base station 100 information identifying each defective element, the defect rate, the defect rate threshold for which the condition was met in the current report, and the like. Furthermore, the base station 100 may cause the control device 130 to periodically report information about defective elements. In this case, the base station 100 may notify the control device 130 of a report setting including a reporting cycle. When the control device 130 is caused to report semi-permanently, the base station 100 may notify the control device 130 of a report setting including a reporting period and a reporting cycle during that period. When the base station 100 requests the control device 130 to report at a time instructed by the base station 100, the base station 100 may notify the control device 130 of a report setting including a time at which the report is to be made. The base station 100 may notify the control device 130 of a report setting including a condition for changing the reporting cycle. As an example, the cycle for making a determination may be changed on the condition that the defect rate exceeds a threshold.

[0028] The control device 130 monitors defective elements or reports information about defective elements based on the monitoring settings or reporting settings notified by the base station 100. The base station 100 may request the control device 130 to perform a monitoring process or a reporting process to check the status of the reflecting elements, regardless of whether the monitoring settings or reporting settings are present. When the control device 130 is requested to perform a monitoring process or a reporting process by the base station, it determines the status of each reflecting element and reports the result to the base station 100. Note that the period included in the monitoring settings or reporting settings may be a frequency. When a unit of time is shared between the base station 100 and the control device 130, the frequency allows notification with a smaller amount of information than the period. Furthermore, the base station 100 may notify the monitoring settings and reporting settings in the same message. By notifying in the same message, the amount of information overhead can be reduced compared to when notifying in multiple messages.

[0029] (Notification of Stop When Defect Rate Exceeds Threshold) When the defect rate in the reflecting device 120 is high, changing the reflection phase of a normally operating reflecting element is likely to result in a failure to form the desired reflection pattern. For example, it may be necessary to replace the reflector or the reflecting device 120 itself. In this embodiment, in such a situation, the control device 130 may stop reporting information about the defective element. The control device 130 may also stop controlling the reflecting device 120. The control device 130 may also turn off the power to the reflecting device 120. By the control device 130 stopping the reporting process or stopping the control of the reflecting device 120, power consumption can be reduced. Furthermore, by the control device 130 stopping the reporting process, wireless resources can be used efficiently. In particular, when the control device 130 is performing connection processing with the base station 100 for reporting, stopping the reporting process has the advantage of eliminating the need for the connection processing.

[0030] The control device 130 may autonomously stop the reporting process when a predetermined condition is satisfied. The control device 130 may notify the base station 100 that the predetermined condition has been satisfied or that the control device 130 will stop the reporting process. Furthermore, when the predetermined condition is satisfied, the control device 130 may autonomously stop controlling the reflecting device 120 or turn off the reflecting device 120. The control device 130 may notify the base station 100 that the predetermined condition has been satisfied and that the control of the reflecting device 120 will be stopped or the power supply of the reflecting device 120 will be turned off. Note that when the power supply of the reflecting device 120 is turned off, the reflecting plate of the reflecting device 120 becomes a reflecting plate that performs, for example, regular reflection or specular reflection, depending on the physical state of the surface of the reflecting plate, on the incident radio waves.

[0031] The conditions under which the control device 130 stops reporting or stops controlling the reflecting device may be notified to the control device 130 by the base station 100. For example, the base station 100 may notify the control device 130 of a reporting setting including a condition under which reporting is stopped. The base station 100 may also notify the control device 130 of a reporting setting including a condition under which control of the reflecting device is stopped. The conditions under which reporting is stopped and the conditions under which control of the reflecting device are stopped may be the same or different from each other. An example of the predetermined condition is when the defect rate exceeds a predetermined threshold. The predetermined condition may be other conditions, such as the number of defective elements exceeding a threshold, or when the reflector is divided into multiple regions, the defect rate in one region exceeds a threshold. The base station 100 may notify the control device 130 of the conditions under which control of the reflecting device is stopped as an instruction to the control device 130, and this instruction and the condition under which the control device 130 stops reporting may be notified in the same message. A notification by the control device 130 to stop reporting, stop control of the reflecting device 120, turn off the power of the reflecting device 120, etc. may be called a stop notification.

[0032] (Method of Notification from Base Station 100 to Control Device 130) The base station 100 may transmit configuration information such as reflecting element configuration, monitoring configuration, and reporting configuration, or the above-mentioned notifications and instructions, to the control device 130 using procedures and frames defined in the 3GPP cellular communication standard. As an example, the base station 100 may notify the control device 130 of the configuration information, etc., using a radio resource control (RRC) message. In this case, for example, a new type of message for notifying the configuration information may be defined in the RRC Reconfiguration message. Upon receiving the RRC message, the control device 130 extracts the configuration information included in the message. Then, the control device 130 controls the reflection phase of each reflecting element, monitors the reflecting elements, and sets up reporting processing for defective elements, etc., according to the extracted configuration information, etc.

[0033] The base station 100 may notify the control device 130 of configuration information and the like using a medium access control (MAC) subheader. In this case, a new MAC subheader format for notifying the configuration information may be defined. Also, some fields of an existing MAC subheader may be diverted to notify the configuration information. For example, a field of a predetermined number of bits for indicating the configuration information may be provided in the MAC subheader. The control device 130 analyzes the MAC subheader included in the signal addressed to the control device 130 to acquire the configuration information. Then, the control device 130 controls the reflection phase of each reflecting element, monitors the reflecting elements, and sets the reporting process for defective elements according to the acquired reflecting element settings.

[0034] To use the RRC message or MAC subheader, an RRC connection must be established between the base station 100 and the control device 130. Therefore, when the RRC message or MAC subheader is used, a processing load such as connection establishment occurs between the base station 100 and the control device 130 each time setting information, etc., is notified. Meanwhile, the control device 130 notifies an acknowledgment indicating that the RRC message or MAC subheader has been successfully received. This acknowledgment notification allows the base station 100 to confirm that the reflection pattern of the reflecting device 120 has been changed and that the control device 130 has configured the monitoring process or reporting process, thereby enabling highly reliable control. Furthermore, since the reflecting element settings set in the reflecting device 120 can be reliably shared between the base station 100 and the reflecting device 120, it is also possible to control the reflecting device 120 by notifying the difference in the reflecting element settings for only the reflecting elements that have been changed. Because the RRC message can contain a large amount of information, when the RRC message is used, the base station 100 can notify the control device 130 of the reflecting element settings using any of the methods described above.

[0035] Furthermore, the base station 100 may notify the control device 130 of the configuration information using downlink control information (DCI) defined in the 3GPP cellular communication standard. In this case, a new DCI format for notifying the configuration information may be defined. Furthermore, a portion of an existing DCI format may be repurposed for notifying the configuration information. For example, a field with a predetermined number of bits for indicating the reflecting element configuration may be provided in the DCI. The control device 130 decodes the physical downlink control channel (PDCCH). In one example, a radio network temporary identifier (RNTI) may be assigned to the control device 130 in advance. In this case, the control device 130 can obtain information from the DCI addressed to the control device 130 by decoding the PDCCH using the RNTI. If the RNTI is assigned in advance, the control device 130 can decode the PDCCH simply by establishing time synchronization on the downlink (the link from the base station 100 to the control device 130) by observing a synchronization signal. That is, in this case, the control device 130 does not need to establish uplink synchronization by executing a random access procedure with the base station 100, or to establish a connection in the RRC layer, so that the connection establishment process can be omitted, thereby reducing the processing load.

[0036] The base station 100 may notify the control device 130 of the configuration information using system information transmitted by broadcast or multicast. An example of the system information is a master information block (MIB) or a system information block (SIB). In this case, a new type of information block may be defined for notifying the reflecting element configuration. Furthermore, some elements of an existing SIB or MIB may be repurposed for notifying the configuration information. In the SIB or MIB, for example, a field with a predetermined number of bits for indicating the configuration information may be provided. When using system information transmitted by broadcast or the like, the information transmitted from the base station 100 is received by all control devices 130 and terminals 110. Therefore, the control device 130 needs to identify whether the received information is intended for the reflecting device 120 controlled and monitored by the base station 100. When notifying the configuration information using transmission by broadcast or the like, the base station 100 may transmit information including information identifying the target control device 130 or reflecting device 120. The control device 130 extracts the configuration information for the control device 130 or the reflecting device 120 connected to the control device 130 from the received system information. Then, the control device 130 controls the reflection phase of each reflecting element, monitors the reflecting elements, and sets the reporting process for defective elements in accordance with the extracted setting information.

[0037] Furthermore, a signaling protocol layer for notifying reflective element settings, monitoring settings, reporting settings, etc. may be defined. For example, the protocol used in this layer may be called an Intelligent Reflecting Surface protocol (IRS protocol). This layer may also be called an IRS protocol layer. For example, the control device 130 receives a message of the IRS protocol layer and, based on the setting information contained in the message, controls the reflection phase of each reflective element, monitors the reflective elements, and sets the reporting process for defective elements. By defining the IRS protocol layer, it becomes possible to use a message format suitable for notifying setting information. Note that the above-mentioned methods for notifying setting information may be used in combination.

[0038] (Method of Notification from the Control Device 130 to the Base Station 100) The control device 130 may report information about defective elements, notify the base station 100 of the stop of reporting processing, notify the base station 100 of the stop of control of the reflection device 120, etc., using procedures and frames specified in the 3GPP cellular communication standard. As an example, the control device 130 may perform the above-mentioned reporting and notification using UE Capability Signaling. UE Capability Signaling is signaling for notifying the base station 100 of the UE's capabilities, and is used after an RRC connection is established with the base station 100. Therefore, more information can be included than when reporting or notifying using, for example, a control channel. For example, the control device 130 may report information about defective elements to the base station 100 using any of the above-mentioned methods by using UE Capability Signaling. Furthermore, by using UE Capability Signaling, a confirmation response indicating that the base station 130 has received the report or notification is sent, thereby enabling highly reliable control. In this case, a new field may be defined in the UE Capability Signaling for the control device 130 to send reports and notifications. The base station 100 extracts, from the UE Capability Signaling, a report of information about each reflecting element, a notification to stop the reporting process, a notification to stop control of the reflecting device 120, and the like.

[0039] The control device 130 may perform the above-described reporting and notification using random access procedure message 1 or message 3. For example, when using random access procedure message 1, the control device 130 may report information about defective elements to the base station 100 by utilizing the availability of multiple preamble patterns. For example, by predetermining preamble patterns according to the information about defective elements to be reported by the control device 130, the control device 130 selects a pattern according to the information about the defective elements to be reported and performs random access. The base station 100 identifies the information about the defective elements based on the pattern selected by the control device 130. A combination of multiple preamble patterns may be used to notify the information about the defective elements. The base station 100 extracts the information about the corresponding defective elements based on the preamble pattern received from the control device 130 via the random access channel. Furthermore, when the control device 130 notifies the base station 100 of the stop of the reporting process or the stop of control of the reflection device 120, for example, a preamble pattern according to the information to be notified may be predetermined between the base station 100 and the control device 130. The control device 130 may select and transmit a preamble pattern according to the information to be notified, thereby notifying the base station 100 of the stop of the reporting process or the stop of control of the reflecting device 120. On the other hand, when the random access procedure message 3 is used, a new field may be defined for the control device 130 to perform reporting and notification. Also, some fields of an existing message may be diverted for the control device 130 to perform reporting or notification. The base station 100 extracts, from the fields in the message, a report of information about each reflecting element, a notification of the stop of the reporting process, a notification of the stop of control of the reflecting device 120, etc.

[0040] The control device 130 may perform the above-described reporting and notification using uplink control information (UCI). In this case, a new UCI format may be defined for the control device 130 to perform the reporting and notification. Alternatively, an existing UCI format may be adapted for use in the reporting or notification by the control device 130. In the UCI, for example, a field with a predetermined number of bits may be provided to indicate information about each reflecting element, the stop of reporting processing, or the stop of control of the reflecting device 120. The base station 100 extracts, from the UCI, the report of information about each reflecting element, the notification of the stop of reporting processing, the notification of the stop of control of the reflecting device 120, etc.

[0041] When the random access procedure message or the UCI is used, it is not necessary to establish an RRC connection between the base station 100 and the control device 130, and therefore it is possible to report or notify without performing processing such as connection establishment. For example, when reports of information on defective elements are frequently required, the control device 130 can report without imposing a large processing load.

[0042] Furthermore, reporting of information about each reflecting element, notification of the stop of the reporting process, and notification of the stop of control of the reflecting device 120 may be performed in the IRS protocol layer. The base station 100 receives a message in the IRS protocol layer and acquires information contained in the message, such as information about each reflecting element, the stop of the reporting process, and the stop of control of the reflecting device 120. By defining a protocol layer for IRS, it becomes possible to use a message format suitable for reporting or notification by the control device 130. Note that the above-mentioned methods of reporting or notification may be used in combination.

[0043] (Device Configuration) Next, an example configuration of the base station 100 and the control device 130 described above will be described. FIG. 3 is a diagram showing the hardware configuration of the base station 100 and the control device 130. In one example, the base station 100 and the control device 130 include a processor 301, a ROM 302, a RAM 303, a storage device 304, and a communication circuit 305. The processor 301 is a computer including one or more processing circuits, such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit). The processor 301 reads and executes programs stored in the ROM 302 or the storage device 304 to perform overall device processing and each of the above-mentioned processes. The ROM 302 is a read-only memory that stores programs related to the processing executed by the base station 100 and the control device 130, various parameters, and other information. The RAM 303 functions as a workspace when the processor 301 executes a program, and is also a random access memory that stores temporary information. The storage device 304 is, for example, a removable external storage device. The communication circuit 305 is configured to include, for example, circuits for wired or wireless communication between the base station 100 and the control device 130. For example, the base station 100 may communicate with the control device 130 using a communication circuit 305 for LTE or 5G for communication with the terminal device 110. However, this is just one example, and the base station 100 may be configured to communicate with the control device 130 using a communication circuit 305 for wired or wireless communication that is prepared separately from the communication circuit 305 for LTE or 5G. The control device 130 has a communication circuit 305 for wireless or wired communication with the base station 100. The control device 130 may also have a communication circuit 305 for (e.g., wired) communication with the reflection device 120. Note that while FIG. 3 illustrates one communication circuit 305, the base station 100 and the control device 130 may have multiple communication circuits. Note that multiple communication functions may be implemented by a single communication circuit 305.

[0044] 4 is a diagram showing an example of the functional configuration of the control device 130. The control device 130 has, as its functions, for example, a monitoring unit 401, a reporting unit 402, an acquisition unit 403, a reflection device control unit 404, and a notification unit 405. Note that these functional units can be realized, for example, by the processor 301 executing a program stored in the ROM 302 or the storage device 304 and controlling the communication circuit 305 as necessary. However, this is not limiting, and for example, dedicated hardware for realizing each function may be prepared.

[0045] The monitoring unit 401 monitors the presence of defective elements in the reflecting device 120. The monitoring unit 401 may monitor the presence of defective elements by periodically determining the state of each reflecting element based on a monitoring setting notified by the base station 100. The monitoring setting indicates, for example, information such as the period at which the monitoring unit 401 determines the state of each reflecting element. The monitoring device 401 may autonomously determine the state of each reflecting element regardless of whether a monitoring setting is present. Alternatively, the monitoring unit 401 may non-periodically determine the state of each reflecting element based on an instruction from the base station 100. If the monitoring unit 401 detects a defective element, it notifies the reporting unit 402.

[0046] The reporting unit 402 reports information about defective elements to the base station 100. The reporting unit 402 may report when a set condition is satisfied based on a reporting setting notified by the base station 100. The reporting setting may indicate, for example, a defect rate threshold as a condition for executing a report. As an example, the reporting unit 402 tallies the number of defective elements notified by the monitoring unit 401 and determines whether the defect rate exceeds the threshold. If the defect rate exceeds the threshold, the reporting unit 402 reports, for example, information identifying the defective elements to the base station 100. The information identifying the defect rate may be information indicating the position of the defective elements on the reflector, or the like. The acquiring unit 403 acquires information necessary for the operation of the control unit 130 from the base station 100. The information necessary for the operation of the control unit 130 includes, for example, a reflecting element setting, a monitoring setting, a reporting setting, and the like. The acquiring unit 403 notifies each function of the information acquired from the base station 100. For example, the acquisition unit 403 notifies the reflection device control unit 404 of the reflection element setting, notifies the monitoring unit 401 of the monitoring setting, and notifies the reporting unit 402 of the reporting setting. The reflection device control unit 404 controls the reflection phase of each reflection element of the reflection device 120. The reflection device control unit 404 may set the reflection phase of each reflection element based on the reflection element setting notified by the base station 100. The reflection element setting includes information specifying the reflection element for which the reflection phase is to be set and information specifying the reflection phase to be set.

[0047] The notification unit 405 notifies the base station 100 of the stop of reporting, the stop of control of the reflection device, etc. For example, if the reporting setting notified from the base station 100 includes a condition for stopping reporting of information about defective elements, the reporting unit 402 notifies the notification unit 405 that this condition has been met. Based on this notification, the notification unit 405 notifies the base station 100 that the condition for stopping reporting has been met. Note that once the condition for stopping reporting is met, the reporting unit 402 does not report to the base station 100 even if the condition for reporting information about defective elements is subsequently met. On the other hand, for example, if the reporting setting notified from the base station 100 includes a condition for stopping control of the reflection device, the reporting unit 402 notifies the notification unit 405 and the reflection device control unit 404 that this condition has been met. Upon receiving this notification, the reflection device control unit 404 stops control of the reflection device 120. Upon receiving this notification, the notification unit 405 notifies the base station 100 that the condition for stopping control of the reflection device has been met. The condition for stopping the control of the reflecting device may be a condition for turning off the power supply of the reflecting device. In this case, the reflecting device control unit 404 may turn off the power supply of the reflecting device 120 when this condition is met, and the notification unit 405 may notify the base station 100 that the condition for turning off the power supply of the reflecting device has been met.

[0048] 5 is a diagram showing an example of the functional configuration of base station 100. Base station 100 has, as its functions, for example, an acquisition unit 501, a reflecting element setting unit 502, a monitoring setting unit 503, and a report setting unit 504. Note that these functional units can be realized, for example, by processor 301 executing a program stored in ROM 302 or storage device 304 and controlling communication circuit 305 as necessary. However, this is not limited to this, and for example, dedicated hardware for realizing each function may be prepared.

[0049] The acquisition unit 501 acquires information about defective elements from the control device 130. The information about defective elements includes, for example, information identifying the defective elements. The acquisition unit 501 notifies the acquired information about the defective elements to the reflecting element setting unit 502. The reflecting element setting unit 502 determines the reflection phase to be set for each reflecting element of the reflecting device 120. The reflecting element setting unit 502 may determine the reflection phase to be set for each reflecting element for each reflection pattern. Upon receiving the information about the defective elements from the acquisition unit 501, the reflecting element setting unit 502 determines whether to change the reflection phase. For example, the reflecting element setting unit 502 identifies a reflection pattern when the reflection phase of the defective element is set to zero, and compares the difference between the peak of the identified reflection pattern and the peak of the reflection pattern when all reflecting elements are operating normally. If the difference exceeds a threshold, the reflecting element setting unit 502 may determine to change the reflection phase. The reflecting element setting unit 502 notifies the control device 130 of the changed reflection element setting.

[0050] The monitoring setting unit 503 and the reporting setting unit 504 generate monitoring settings and reporting settings for controlling the monitoring process and reporting process executed by the control device 130, respectively, and notify the control device 130. The monitoring settings may include, for example, a period at which the control device 130 determines the state of the reflecting element. The reporting settings may also include, for example, a condition under which the control device 130 reports a defective element. The reporting settings may also include a condition under which the control device 130 stops the reporting process or stops control of the reflecting device. When the condition for stopping the reporting process or the condition for stopping control of the reflecting device is satisfied, the acquisition unit 501 receives, from the control device 130, a notification of the stop of reporting or a notification of the stop of control of the reflecting device. When receiving these notifications, the base station 100 may execute a procedure or process for communicating with the terminal 110 without going through the reflecting device 120.

[0051] (Processing Flow) Next, an example of the flow of processing executed in the wireless communication system will be described. Note that, since the details of the processing are as described above, an overview of the processing flow will be provided here, and the details will not be repeated.

[0052] FIG. 6 shows an example of a processing flow when the control device 130 reports a detected defective element to the base station 100 and the base station 100 notifies the control device 130 of the reflecting element setting to be set in the reflecting device 120. It is assumed that the pattern ID and reflecting element setting for each reflection pattern are shared in advance between the base station 100 and the control device 130. First, the base station 100 determines a reflection pattern for communication with the terminal 110 (S601) and notifies the control device 130 of the pattern ID corresponding to this reflection pattern (S602). The control device 130 determines the reflection phase of each reflecting element of the reflecting device 120 according to the notified pattern ID (S603). For example, the control device 130 may have a table indicating the reflection phase of each reflecting element for each pattern ID. The control device 130 sets each reflecting element of the reflecting device 120 using the determined reflection phase (S604). Here, it is assumed that a defective element has occurred in the reflecting device 120 (S605). The control device 130 periodically monitors the reflecting elements (S606) and detects defective elements by determining the state of each reflecting element (S607). The control device 130 reports information about the detected defective elements to the base station 100 (S608). As described above, the control device 130 may report information about defective elements when conditions are met, according to a reporting setting previously notified by the base station 100. The base station 100 generates a new reflecting element setting based on the reported defective element information (S609). The method for generating the reflecting element setting may be any of the methods described above, or may be another method. The base station 100 notifies the control device 130 of the generated reflecting element setting (S610). The control device 130 determines the reflection phase to be set for each reflecting element of the reflecting device 120 according to the notified reflecting element setting (S611). The control device 130 sets each reflecting element of the reflecting device 120 using the determined reflection phase (S612). In this way, the control device 130 can detect a defective element that occurs in the reflection device 120, notify the base station 100 of information about the defective element, and the base station 100 can control the reflection phase of the reflection element to change based on the notified information about the defective element.

[0053] FIG. 7 shows an example of a process flow when the control device 130 performs monitoring and reporting of defective elements according to the monitoring settings and reporting settings generated by the base station 100. First, the base station 100 determines the period during which the control device 130 monitors the reflecting device 120 and the conditions under which the control device 130 reports defective elements, and generates the monitoring settings and reporting settings (S701). For example, the reporting settings indicate that the condition for reporting a defective element is that the defect rate exceeds a first threshold value of 0.1 or a second threshold value of 0.2. The base station 100 notifies the generated monitoring and reporting settings to the control device 130 (S702). Now, suppose that a defective element has occurred in the reflecting device 120 (S703). The control device 130 periodically determines the status of each reflecting element in the reflecting device 120 according to the monitoring settings notified by the base station 100, and detects the defective element (S704). Here, for example, if the defect rate calculated by the control device 130 exceeds the first threshold, the condition specified in the reporting setting is satisfied (S705), and the control device 130 reports information about the defective element to the base station 100 (S706). The processing flow from S707 to S710 is similar to S609 to S612 in FIG. 6 , so a description thereof will be omitted. Next, assume that another defective element occurs in the reflecting device 120 (S711). The control device 130 continues to monitor the defective element even after changing the reflection phase of each reflecting element. If the control device 130 detects a defective element (S712), and the defect rate calculated by the control device 130 exceeds the second threshold of 0.2 specified in the reporting setting (S713), for example, the control device 130 reports information about the defective element to the base station 100 (S714). In this way, it is possible to control the control device 130's monitoring of reflecting elements and reporting of defective elements based on the monitoring installation and reporting setting generated by the base station 100.

[0054] FIG. 8 shows an example of a processing flow when the control device 130 stops reporting information about defective elements or stops control of the reflection device 120. First, the base station 100 determines the conditions under which the control device 130 stops reporting information about defective elements or the conditions under which the control device 130 stops control of the reflection device 120 (S801). These conditions may be the same or different. For example, the base station 100 determines that the defect rate exceeds a predetermined threshold as the same condition and notifies the control device 130 (S802). The condition notification may be included in the reporting setting notified from the base station 100 to the control device 130. Assume that a defective element has occurred in the reflection device 120 (S803). The control device 130 periodically evaluates the status of each reflection element and detects the defective element (S804). Here, for example, if the defect rate calculated by the control device 130 exceeds the predetermined threshold, the set condition is satisfied (S805), and the control device 130 notifies the base station 100 that the condition has been met (S806). Furthermore, the control device 130 stops the control of the reflecting device 120 and performs control to turn off the power supply of the reflecting device 120 (S807). Then, the control device 130 notifies the base station 100 that the control of the reflecting device 120 has been stopped or that the power supply of the reflecting device 120 has been turned off (S808). The reflecting device 120 turns off its own power supply in accordance with the control from the control device 130 (S809). In this way, it becomes possible to stop reporting information about defective elements in the control device 130 and stop control of the reflecting device 120 based on the conditions set by the base station 100.

[0055] As described above, according to this embodiment, the control device 130 autonomously monitors the state of the reflecting elements of the reflecting device 120 and reports information about defective elements to the base station. Furthermore, the base station identifies the reflection phase to be set for the reflecting element based on the reported information about the defective element and notifies the reflecting device 120. The reflecting device 120 controls the reflecting element of the reflecting device 120 according to the notified reflection phase. This makes it possible to efficiently detect defective elements in a wireless communication system that uses a reflector.

[0056] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.

[0057] This application claims priority based on Japanese Patent Application No. 2023-144674, filed September 6, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A monitoring device that monitors a reflecting device that uses a reflecting plate composed of a plurality of reflecting elements to reflect radio waves transmitted from a base station, the monitoring device comprising: a monitoring means for monitoring the state of the reflecting elements that compose the reflecting plate; and a notification means for notifying the base station of detection information of a defective element, which is a reflecting element that is not operating normally, when the monitoring means detects such a defective element.

2. The monitoring device according to claim 1, wherein the detection information includes identification information capable of identifying the defective element.

3. The monitoring device according to claim 2, wherein the specific information is an identifier of the defective element.

4. The monitoring device according to claim 2, wherein the specific information is a position of the defective element on the reflector.

5. The monitoring device according to claim 1, wherein the detection information includes the number of the defective elements or a defect rate which is a ratio of the defective elements to the reflecting elements constituting the reflector.

6. The monitoring device according to any one of claims 1 to 5, wherein the notification means notifies the base station of the detection information using at least one of UE Capability Signaling in a cellular communication standard of the Third Generation Partnership Project (3GPP), message 1 or message 3 of a random access procedure, uplink control information, and a protocol for Intelligent Reflecting Surface.

7. A control method executed by a monitoring device that monitors a reflecting device that reflects radio waves transmitted from a base station using a reflector composed of a plurality of reflecting elements, the control method comprising: monitoring the state of the reflecting elements that compose the reflector; and, when a defective element that is a reflecting element that is not operating normally is detected, notifying the base station of detection information of the defective element.

8. A program for causing a computer installed in a monitoring device that monitors a reflecting device that uses a reflector composed of multiple reflecting elements to monitor the state of the reflecting elements that compose the reflector, and for notifying the base station of the detection information of the defective element when a defective element that is not operating normally is detected.

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