Monitoring device, control method, and program for managing state of reflector

Abstract

To provide a technique for efficiently detecting defective elements in a wireless communication system that uses a reflector.SOLUTION: 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 monitors the state of the reflecting elements that make up the reflector, and when the monitoring means detects a defective element, which is a reflecting element that is not operating normally, notifies the base station of detection information of the defective element.SELECTED DRAWING: Figure 6

Description

[Technical field]

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

[0002] In mobile communications, wireless communication services are provided to terminals located in positions where radio waves transmitted from base stations can be received. For this reason, it is important that the radio waves transmitted from the base station reach the terminals 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 base stations and terminals has been considered. Note that the reflector can change the direction in which the radio waves are reflected by changing its physical orientation, but by using a metasurface reflector, it is possible to reflect radio waves in various directions by electrical control without changing the physical orientation. Non-Patent Document 1 describes a technology in which a base station controls the reflection pattern of radio waves on a reflector by transmitting control information to a control device of the reflector. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Wu, Qingqing and Rui Zhang, "Intelligent reflecting surface enhanced wireless network:Joint active and passive beamforming design", 2018 IEEE Global Communication Conference (GLOBECOM), 2018. Summary of the Invention [Problem to be solved by the invention]

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

[0005] A monitoring device according to one embodiment 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 for monitoring the state of the reflecting elements that constitute the reflecting plate, and a notification means for, when the monitoring means detects a defective element, which is a reflecting element that is not operating normally, notifying the base station of detection information of the defective element. Effect of the Invention

[0006] According to the present invention, it is possible to efficiently detect defective elements in a wireless communication system using a reflector. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system. [Diagram 2] FIG. 13 is a diagram illustrating an example of a reflective element setting. [Diagram 3] FIG. 2 is a diagram illustrating an example of the hardware configuration of a base station and a control device. [Figure 4] FIG. 2 is a diagram illustrating an example of a functional configuration of a control device. [Diagram 5] FIG. 2 is a diagram illustrating an example of a functional configuration of a base station. [Figure 6] 11 is a diagram showing a process flow in which a control device reports information on a defective element to a base station, and the base station notifies the control device of a reflective element setting. [Figure 7] 11 is a diagram showing a process flow when a control device executes a monitoring process and a reporting process for a defective element. FIG. [Figure 8] 13 is a diagram showing a process flow when the control device stops reporting a defective element or stops controlling a reflection device. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more features among the multiple features described in the embodiments may be arbitrarily combined. Also, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0009] (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, the present invention 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, reflection devices 121 and 122, and control devices 131 and 132. In this embodiment, the base stations 101 to 103 may be called base station 100 without distinction. Also, the terminals 111 and 112 may be called terminal 110 without distinction, the reflection devices 121 and 122 may be called reflection device 120 without distinction, and the control devices 131 and 132 may be called control device 130 without distinction. Here, the base station 103 is assumed to be a base station constituting a cell 143 having a larger coverage than 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).

[0010] Here, for example, suppose that there is a shield between the base station 101 and the terminal 111, and the radio wave transmitted from the base station 101 is not received at the terminal 111 with sufficient strength. In this case, the radio wave transmitted from the terminal 111 may not be received at the base station 101 with sufficient strength. In the cell of the base station 100, a place where the radio wave transmitted from the base station 100 is not received with sufficient strength may be called a dead zone. In particular, when radio waves in a high frequency band are used, the possibility of a dead zone occurring increases. In such a situation, by disposing the reflecting device 121 at 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 the radio wave transmitted from the base station 101 in a predetermined reflection pattern. Also, the reflecting device 121 reflects the radio wave transmitted from the terminal 111 in a predetermined reflection pattern. By appropriately setting the reflection pattern of the reflector 121, it is possible to reflect radio waves transmitted from the base station 101 in the direction of the terminal 111, and to reflect radio waves transmitted from the terminal 111 in the direction of the base station 101. As a result, the radio waves transmitted from the base station 101 can be received by the terminal 111 with sufficient strength, and the 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 indicating the gain of the reflector for each direction, and is determined by the reflection phase set in the reflection element constituting the reflector of the reflector 120. For example, the pattern is one 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. Also, radio waves emitted in a specific direction are emitted with high power, and almost no radio waves are emitted in another direction. In this way, the reflection pattern is expressed by a combination of patterns indicating the gains of the incident and emitted respectively.

[0011] 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 device or may be implemented separately. The control device 131 may control the reflecting device 121 so that a predetermined fixed reflection pattern is formed. In addition, the control device 131 and the base station 101 are wirelessly connected, so that 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 includes a wide area including the cells 141 and 142 of the base stations 101 and 102 in its cell 143, and the base stations 101 to 103 belong to the same network domain and can 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 that 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, the base station covering a wide area can centrally control the reflecting devices via the control device, thereby making it possible to manage the entire wireless communication system in an integrated manner and eliminate more blind zones.

[0012] The same discussion can be applied to the 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 a shield or the like, a reflector 122 is installed and the control device 132 controls the reflector 122, thereby enabling communication between the base station 102 and the terminal 112. The configuration in FIG. 1 is merely an example. For example, the number of reflectors that relay communication between the base station 100 and the terminal 110 may be one or more than two. Also, a large number of terminals may be connected to the base station 100. In this case, some terminals may directly communicate with the base station 100 without going through the reflector 120, and other terminals may communicate with the base station 100 via the reflector 120.

[0013] 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 the reflector 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 is, for example, composed of a plurality of reflecting elements, and the reflection pattern can be formed by controlling the reflection phase of each reflecting element. As an example, a metasurface reflecting device using liquid crystal may have a reflector in which a liquid crystal layer is 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 changes, and the reflection phase of the reflecting element changes according to the change in the dielectric constant of the liquid crystal. In this way, by changing the voltage applied to the reflecting element, it is possible to finely control the reflection phase of the reflecting element, so that the reflecting plate can be controlled so that a desired reflection pattern is formed by adjusting the voltage applied to each of the reflecting elements that constitute the reflecting plate. In this way, by using a metasurface, it is possible to change the reflection direction of the radio wave without physically changing the orientation or posture of the reflecting device. The reflecting device 120 may have other reflection mechanisms. For example, the reflecting device 120 may include a reflecting plate by an IRS using a diode. In a metasurface reflecting plate using a diode, the reflecting element and the circuit element are connected by a diode, and a current flows in the circuit by applying a voltage to the diode, and as a result, the reflection phase of the reflecting element changes. 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 liquid crystal.

[0014] The control device 130 controls the reflection pattern of the reflecting device 120. For example, the control device 130 has setting information (reflection element setting) in which the reflection phase to be set for each reflection element is specified. The control device 130 controls the reflection phase of each reflection element according to this reflection element setting. As an example, the reflection element setting includes information for identifying each reflection element and information for identifying the reflection phase to be set for each reflection element. The information for identifying each reflection element may be the position of each reflection element on the reflector, or may be an identifier of the reflection element. In addition, the information for identifying the reflection phase of each reflection element may be an absolute value of the reflection phase, or may be a relative value with respect to a reference value of the reflection phase. The information included in the reflection element setting is not limited to these, and the information for identifying each reflection element and the information for identifying the reflection phase of each reflection element are not limited to these. The reflection element setting may exist for each reflection pattern formed by the reflection device 120. For example, when 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 reflection element of the reflector according to the reflection element setting associated with each pattern ID.

[0015] 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 reflection element setting for each reflection 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 reflection element setting, and a device other than the base station 100 may notify the control device 130 of the reflection element setting. When the reflection pattern and the reflection element setting are previously associated 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. That is, the control device 130 sets the reflection phase of each reflection element of the reflecting device 120 according to the reflection element setting associated with the notified pattern ID. Note that the information notified to the control device 130 by the base station 100 is not limited to the pattern ID. For example, the reflection element setting itself may be notified.

[0016] If there is a defective element among the reflecting elements constituting the reflector, the desired reflection pattern may not be formed. In this embodiment, a reflecting element that does not operate normally is called a defective element. As an example, a defective element may be generated due to damage to the reflecting element itself, deterioration of the electrical characteristics of the liquid crystal constituting the reflector, failure of the circuit that applies a voltage to the reflecting element, etc. The causes of the generation of defective elements are not limited to those described above. For example, even if a predetermined voltage according to the reflecting element setting is applied to a reflecting element whose electrical characteristics of the liquid crystal are deteriorated, the liquid crystal may not have the desired dielectric constant, and as a result, the reflection phase of the reflecting element may not be the desired phase. If the reflection phase of the defective element is different from the desired reflection phase, the desired reflection pattern is not formed as the reflection pattern of the reflecting device 120. In this way, if the desired reflection pattern is not formed due to the presence of a defective element, for example, the radio wave transmitted by the base station 100 and reflected by the reflecting device 120 may not be received with sufficient strength at the terminal 110. If sufficient power is not received, the blind zone is not eliminated and the area coverage is deteriorated. Furthermore, if a peak of the reflection pattern is formed in a direction different from the desired direction, this may result in a decrease in the accuracy of azimuth estimation and beam training.

[0017] In order to grasp 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 workers or the like to the site to perform periodic measurements. In addition, by receiving a report on the reception status of radio waves from the user who uses the terminal 110, the performance deterioration of the reflector of the reflecting device 120 may be grasped. In this embodiment, in consideration of such a situation, a method is provided 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 grasp the presence of a defective element early and efficiently maintain and operate the reflecting device 120 without dispatching workers or the like to the site. Hereinafter, the process of detecting and reporting a defective element in this embodiment will be described.

[0018] (Detection and reporting of defective elements) The control device 130 monitors the state of each reflective element in the reflector of the reflecting device 120. As an example, the control device 130 periodically applies a predetermined voltage to each reflective element to determine whether each reflective element is operating normally, 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 of 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 when the difference exceeds a threshold value, determines that the reflective element is not operating normally. Note that the method of determining whether each reflective element is operating normally is not limited to this method, 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 such a determination process for each reflective element to monitor the state of each reflective element.

[0019] The control device 130 reports the state of each reflecting element in the reflector of the reflecting device 120 to the base station 100. For example, the control device 130 reports detection information of the detected defective element to the base station 100. As an example, the detection information is identification information capable of identifying the defective element. The identification information may be the position of the defective element in the reflector. For example, when the reflector is composed of M rows x N columns of reflecting elements, the position of the defective element can be identified by a combination of the row number and the column number. In addition, when an identifier capable of uniquely identifying the reflecting element on the reflector is assigned to each reflecting element, the control device 130 may identify the defective element using the identifier. Note that the method of identifying the defective element is not limited to these. In addition, the control device 130 may report the number of detected defective elements and the defect rate to the base station 100 as the detection information. Note that in this embodiment, the ratio of defective elements to the reflecting elements constituting the reflector is called the defect rate. By using the number of defective elements and the defect rate, the control device 130 can report the state of the reflecting elements in the reflecting device 120 to the base station 100 with a smaller amount of information than when notifying information on each individual defective element.

[0020] (Change in reflection phase) When base station 100 receives information on defective elements from control device 130, it may change the reflection phase set for each reflecting element based on the reported information on the defective elements. For example, when reflecting element settings that assume the occurrence of defective elements are shared in advance between base station 100 and control device 130, base station 100 may notify control device 130 of information that identifies the reflecting element settings. Control device 130 may change the reflection phase of each reflecting element according to the notified information.

[0021] The base station 100 may newly generate a 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, when a reflector is composed of reflecting elements with M rows and N columns, 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 0 or 1 is randomly arranged as each element of the matrix. P is an arbitrary integer. Here, the value of the element corresponding to the defective element in the matrix 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. When 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 function is kept, the remaining 50% is discarded, and the top 50% is used to generate new rows so that there are P columns again. The generated matrix is ​​used to calculate the objective function for each row. This process is repeated until the convergence condition is satisfied, and the surviving components are selected as the reflection phase of each reflection element. In this way, by using a genetic algorithm, it is possible to generate a reflection element setting that forms a desired reflection pattern in a situation where a defective element is present.

[0022] The method of generating the reflection element setting is not limited to the method using the genetic algorithm. For example, the base station 100 may generate a new reflection element setting by adding a predetermined common phase to the reflection phase of each reflection element in the current reflection element setting. For example, the influence of a reflection element not operating normally may be caused by the difference between the phase to be set in the reflection element by the reflection element setting and the reflection phase of the actual defective element. Assuming that the reflection phase of the actual defective element becomes zero, the influence of the defective element can be reduced while maintaining the current reflection pattern by adding a common phase to the reflection phase of all reflection elements so that the reflection phase of the defective element in the reflection element setting becomes zero. In this case, the base station 100 may notify the control device 130 of the change amount of the common reflection phase to be added to the reflection phase of each current reflection element. When the reflection 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 reflection element of the reflection device 120 according to the reflection element setting.

[0023] (Reflection phase notification) When the base station 100 notifies the control device 130 of the reflecting element settings generated, the amount of information to be notified may be huge. For example, assuming that a reflector of 100 wavelength size 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. In addition, the reflecting element settings may include redundant information. A method of efficiently notifying the reflection phase in this embodiment will be described using an example of the reflecting element settings shown in FIG. 2. In FIG. 2(A), the base station 100 extracts the difference 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 reflecting elements in M ​​rows x N columns, the amount of information to be notified from the base station 100 to the control device 130 can be reduced to D / (M x N) by notifying only the settings of the reflecting elements with differences. In FIG. 2B, when the reflection phases for some of the reflection elements in the generated reflection element setting are a common value, the base station 100 aggregates the reflection 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 reflection element to which this reflection phase is set and notifies the control device 130. This makes it possible to reduce the amount of reflection phase information corresponding to the number of aggregated reflection elements. In FIG. 2C, when the reflection phases to be set for some of the reflection elements in the generated reflection 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 reflection element to be set and notifies the control device 130. An example of the common regularity is to set reflection phases for reflection elements in a predetermined range by increasing the phase by the same amount, with a defective element as a reference. FIG. 2C shows a rule for setting the reflection phase of each reflection element while increasing it by 10[deg] 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 for notifying the reflective element setting.For example, an identifier may be assigned to each notification method, and when processing a connection between the base station 100 and the control device 130, 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. Also, the base station 100 may notify the control device 130 of the notification method to be used every time the base station 100 notifies the control device 130 of the 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 same.

[0024] (Control of monitoring and reporting processes by 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, thereby enabling efficient maintenance and operation of the reflection device 120. On the other hand, if defective elements are frequently reported from a large number of control devices 130, the amount of information for the report becomes large, which may affect data communication. For example, if the report of the defective element 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, causing delays in data communication. In addition, if the defect rate is low, the impact of the defective element 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 on the defective elements performed by each control station 130.

[0025] The base station 100 generates, for example, a monitoring setting for controlling the monitoring of defective elements performed by the control device 130, and notifies the control device 130 of the monitoring setting. As an example, in a case where the control device 130 is made to periodically determine the state of each reflecting element and report the determination result, the base station 100 notifies the control device 130 of the monitoring setting including the period for performing the determination. Also, for example, in a case where the control device 130 is made to perform the monitoring process semi-permanently, the base station 100 notifies the control device 130 of the monitoring setting including the period for performing the determination and the period for performing the determination 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 the monitoring setting including the time for performing the determination. Also, the base station 100 may notify the control device 130 of the monitoring setting including the condition for changing the period for performing the determination. As an example, the period for performing the determination may be changed on the condition that the defect rate exceeds a threshold. In this case, base station 100 notifies control processing device 130 of a monitoring setting including a defect rate threshold as a condition for changing the determination period, and the periods for making determination before and after the condition is satisfied.

[0026] Also, the base station 100 may generate a report setting for controlling the reporting of information on defective elements executed by the control device 130, and notify the control device 130 of the report setting. As an example, when controlling the control device 130 to report when a certain condition is satisfied, the base station 100 notifies the control device 130 of a report setting including the condition. For example, when the condition is that the failure rate exceeds a threshold, the base station 100 notifies the control device 130 of a report setting including a threshold value of the failure rate. Also, when making the control device 130 report further after the failure rate exceeds a threshold value, the report setting may include multiple threshold values ​​of the failure rate. For example, when the first to third threshold values ​​are set to 0.1, 0.2, and 0.3, respectively, in the report setting, the control device 130 that receives this executes a report to the base station 100 when the failure 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 failure rate, the threshold value of the failure rate whose condition is satisfied in the current report, and the like. Furthermore, the base station 100 may cause the control device 130 to periodically report information on defective elements. In this case, the base station 100 may notify the control device 130 of a report setting including a cycle for making a report. When making the control device 130 make a semi-permanent report, the base station 100 may notify the control device 130 of a report setting including a period for making a report and a cycle for making a report during that period. When requesting the control device 130 to make a report at a time specified by the base station 100, the base station 100 may notify the control device 130 of a report setting including a time for making a report. The base station 100 may notify the control device 130 of a report setting including a condition for changing the cycle for making a report. As an example, the cycle for making a judgment may be changed on the condition that the defect rate exceeds a threshold.

[0027] The control device 130 monitors defective elements or reports information on defective elements based on the monitoring setting or reporting setting notified from the base station 100. The base station 100 may request the control device 130 to execute a monitoring process or a reporting process to check the state of the reflecting element, regardless of the presence or absence of the monitoring setting or the reporting setting. When the control device 130 is requested to execute a monitoring process or a reporting process by the base station, the control device 130 judges the state of each reflecting element and reports the result to the base station 100. The period included in the monitoring setting or the reporting setting may be a frequency. When a unit 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. The base station 100 may also notify the monitoring setting and the reporting setting in the same message. By notifying in the same message, the amount of information for overhead can be reduced compared to when notifying in multiple messages.

[0028] (Notification of stop if defect rate exceeds threshold) When the defect rate in the reflecting device 120 is large, even if the reflection phase of the reflecting element operating normally is changed, the desired reflection pattern is likely not formed. For example, the reflector or the reflecting device 120 itself may need to be replaced. In this embodiment, in such a situation, the control device 130 may stop reporting information on the defective element. Also, the control device 130 may stop controlling the reflecting device 120. The control device 130 may turn off the power supply of the reflecting device 120. By the control device 130 stopping the report process or stopping the control of the reflecting device 120, it is possible to reduce power consumption. Also, by the control device 130 stopping the report process, it is possible to efficiently use wireless resources. In particular, when the control device 130 is performing a connection process with the base station 100 for reporting, there is an advantage in that the connection process is not required by stopping the report process.

[0029] When a predetermined condition is satisfied, the control device 130 may autonomously stop the reporting process. The control device 130 may notify the base station 100 that the predetermined condition is satisfied or that the control device 130 will stop the reporting process. When a predetermined condition is satisfied, the control device 130 may autonomously stop the control of the reflection device 120 or turn off the reflection device 120. The control device 130 may notify the base station 100 that the predetermined condition is satisfied and that the control of the reflection device 120 will be stopped or the power supply of the reflection device 120 will be turned off. When the power supply of the reflection device 120 is turned off, the reflector of the reflection device 120 becomes a reflector that performs, for example, regular reflection or specular reflection, depending on the physical state of the surface of the reflector, with respect to the incident radio wave.

[0030] The condition for the control device 130 to stop the report or the condition for the control device 130 to stop the control of the reflection device may be notified from the base station 100 to the control device 130. For example, the base station 100 may notify the control device 130 of a report setting including a condition for stopping the report. Also, the base station 100 may notify the control device 130 of a report setting including a condition for stopping the control of the reflection device. The condition for stopping the report and the condition for stopping the control of the reflection device may be the same or different from each other. An example of the predetermined condition may be that the failure rate exceeds a predetermined threshold. The predetermined condition may be other conditions such as the number of defective elements exceeding a threshold, or the failure rate in a part of the areas when the reflector is divided into multiple areas exceeding a threshold. The base station 100 may notify the condition for stopping the control of the reflection device as an instruction to the control device 130, and may notify this instruction and the condition for the control device 130 to stop the report in the same message. Notifications such as the control device 130 stopping the report process, stopping the control of the reflection device 120, and turning off the power of the reflection device 120 may be called stop notifications.

[0031] (Method of notifying the base station 100 to the control device 130) The base station 100 may transmit setting information such as reflecting element setting, monitoring setting, and reporting setting, or the above-mentioned notification and instruction to the control device 130 using a procedure and a frame defined in the 3GPP cellular communication standard. As an example, the base station 100 notifies the control device 130 of the setting information, etc., using a radio resource control (RRC) message. In this case, for example, a new type of message for notifying the setting information may be defined in the RRC Reconfiguration message. Upon receiving the RRC message, the control device 130 extracts the setting information included in the message. Then, the control device 130 controls the reflection phase of each reflecting element, monitors the reflecting elements, and sets the reporting process of defective elements according to the extracted setting information, etc.

[0032] The base station 100 may notify the control device 130 of the setting information and the like by using a medium access control (MAC) subheader. In this case, a new MAC subheader format for notifying the setting information may be defined. Also, some fields of the existing MAC subheader may be diverted to notify the setting information. In the MAC subheader, for example, a field of a predetermined number of bits for indicating the setting information may be prepared. The control device 130 analyzes the MAC subheader included in the signal addressed to the control device 130 to obtain the setting information. Then, the control device 130 performs control of the reflection phase of each reflecting element, a process of monitoring the reflecting elements, a process of reporting defective elements, and the like according to the obtained reflecting element setting.

[0033] In order to use the RRC message or the MAC subheader, an RRC connection must be established between the base station 100 and the control device 130. Therefore, when the RRC message or the MAC subheader is used, a processing load such as connection establishment occurs between the base station 100 and the control device 130 every time setting information or the like is notified. On the other hand, the control device 130 notifies an acknowledgement indicating that the RRC message or the MAC subheader has been normally received. By notifying the acknowledgement, the base station 100 can confirm that the reflection pattern of the reflecting device 120 has been changed and that the control device 130 has set the monitoring process or the reporting process, and can perform highly reliable control. In addition, since the reflecting element setting set in the reflecting device 120 can be shared reliably 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 setting for only the reflecting element that has been changed. Since the RRC message can contain a lot of information, when the RRC message is used, the base station 100 can notify the control device 130 of the reflecting element setting by any of the above-mentioned methods.

[0034] Also, the base station 100 may notify the control device 130 of the setting information by using downlink control information (DCI) defined in the 3GPP cellular communication standard. In this case, a new DCI format for notifying the setting information may be defined. Also, a part of an existing DCI format may be diverted to notify the setting information. In the DCI, for example, a field of a predetermined number of bits for indicating a reflecting element setting may be prepared. The control device 130 decodes a 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. When the RNTI is assigned in advance, the control device 130 can decode the PDCCH by simply establishing time synchronization of the downlink (a 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 execute a random access procedure to establish uplink synchronization with the base station 100, or to establish a connection in the RRC layer. Therefore, the connection establishment process and the like can be omitted, and the processing load can be reduced.

[0035] The base station 100 may notify the control device 130 of the setting information by 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 for notifying the reflecting element setting may be defined. Also, some elements of the existing SIB or MIB may be diverted to notify the setting information. In the SIB or MIB, for example, a field of a predetermined number of bits for indicating the setting information may be prepared. When using system information transmitted by broadcast or the like, the information transmitted from the base station 100 is received by all the control devices 130 and the terminals 110. For this reason, the control device 130 needs to identify whether the received information is information targeted at the reflecting device 120 controlled and monitored by the control device 130. When the base station 100 notifies the setting information by using transmission by broadcast or the like, the base station 100 may transmit the information including information for identifying the target control device 130 or reflecting device 120. The control device 130 extracts the setting 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.

[0036] Also, a protocol layer for signaling for notifying the reflecting element setting, the monitoring setting, the reporting setting, or the like may be defined. For example, the protocol used in this layer may be called the Intelligent Reflecting Surface protocol (IRS protocol). Also, this layer may be called the IRS protocol layer. For example, the control device 130 receives a message of the IRS protocol layer, and performs control of the reflection phase of each reflecting element, the monitoring process of the reflecting element, the setting of the reporting process of the defective element, and the like based on the setting information contained in the message. By defining the IRS protocol layer, it becomes possible to use a message format suitable for notifying the setting information. Note that the above-mentioned methods for notifying the setting information may be used in combination.

[0037] (Method of notifying the base station 100 from the control device 130) The control device 130 may report information on defective elements, notify the base station 100 of the stop of the report process, notify the base station 100 of the stop of the control of the reflection device 120, and the like, using a procedure or frame specified in the 3GPP cellular communication standard. As an example, the control device 130 may perform the above-mentioned report and notification using UE Capability Signaling. UE Capability Signaling is signaling for notifying the base station 100 of the functions of the UE, and is used after an RRC connection is established with the base station 100. For this reason, it can include more information than when the report or notification is performed using a control channel or the like. For example, the control device 130 may report information on defective elements to the base station 100 by any of the above-mentioned methods by using UE Capability Signaling. In addition, by using UE Capability Signaling, a confirmation response indicating that the base station 130 has received the report or notification is notified, so that highly reliable control can be performed. In this case, a new field for the control device 130 to perform the report and notification may be defined in the UE Capability Signaling. The base station 100 extracts, from the UE Capability Signaling, a report of information on each reflecting element, a notification to stop the reporting process, a notification to stop the control of the reflecting device 120, and the like.

[0038] The control device 130 may perform the above-mentioned report and notification using the random access procedure message 1 or message 3. For example, when the random access procedure message 1 is used, the control device 130 may report information on the defective element to the base station 100 by utilizing the fact that a plurality of preamble patterns are prepared. For example, by predetermining a preamble pattern according to the information on the defective element to be reported by the control device 130, the control device 130 selects a pattern according to the information on the defective element to be reported and performs random access. The base station 100 identifies the information on the defective element based on the pattern selected by the control device 130. A combination of a plurality of preamble patterns may be used to notify the information on the defective element. The base station 100 extracts the information on the corresponding defective element based on the pattern of the preamble received from the control device 130 in the random access channel. In addition, when the control device 130 notifies the stop of the report process or the stop of the 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 the 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 the reporting and notification. Also, some fields of an existing message may be diverted for the control device 130 to perform the reporting or notification. The base station 100 extracts the report of the information of each reflecting element, the notification of the stop of the reporting process, the notification of the stop of the control of the reflecting device 120, etc. from the fields in the message.

[0039] The control device 130 may perform the above-mentioned reporting and notification using uplink control information (UCI). In this case, a new UCI format for the control device 130 to perform the reporting and notification may be defined. Also, an existing UCI format may be diverted for the control device 130 to perform the reporting or notification. In the UCI, for example, a field of a predetermined number of bits may be prepared to indicate the information of each reflecting element, the stop of the reporting process, and the stop of the control of the reflecting device 120. The base station 100 extracts the report of the information of each reflecting element, the notification of the stop of the reporting process, the notification of the stop of the control of the reflecting device 120, etc. from the UCI.

[0040] When the random access procedure message or UCI is used, it is not necessary to establish an RRC connection between the base station 100 and the control device 130, so that the report or notification can be made without performing processing such as connection establishment. For example, when the report of information on defective elements is frequently required, the control device 130 can make the report without imposing a large processing load.

[0041] Furthermore, the reporting of information on each reflecting element, the notification of the stop of the reporting process, and the notification of the stop of the 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 obtains information, such as information on each reflecting element, the stop of the reporting process, and the stop of the control of the reflecting device 120, contained in the message. By defining the protocol layer for IRS, it becomes possible to use a message format suitable for the reporting or notification by the control device 130. Note that the above-mentioned methods of reporting or notifying may be used in combination.

[0042] (Device configuration) Next, a configuration example of the base station 100 and the control device 130 as 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 are configured to 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 configured to include 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 and the storage device 304 to execute the overall processing of the device and each of the above-mentioned processes. The ROM 302 is a read-only memory in which information such as programs and various parameters related to the processing executed by the base station 100 and the control device 130 is recorded. The RAM 303 functions as a workspace when the processor 301 executes a program, and is a random access memory in which temporary information is recorded. The storage device 304 is, for example, configured by a removable external storage device. The communication circuit 305 is configured to include, for example, a circuit for wired communication or wireless communication of the base station 100 and the control device 130. For example, the base station 100 may communicate with the control device 130 using the communication circuit 305 for LTE or 5G for communication with the terminal device 110. However, this is only an 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 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 for communicating with the base station 100. The control device 130 may further have a communication circuit 305 for (for example, wired) communication with the reflection device 120. Note that, although one communication circuit 305 is illustrated in FIG. 3, the base station 100 and the control device 130 may have multiple communication circuits. Note that multiple communication functions may be implemented by one communication circuit 305.

[0043] 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 acquiring unit 403, a reflection device control unit 404, and a notifying 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 limited to this, and for example, dedicated hardware for realizing each function may be prepared.

[0044] 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 judging 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 a period at which the monitoring unit 401 judges the state of each reflecting element. The monitoring device 401 may autonomously judge the state of each reflecting element regardless of the presence or absence of a monitoring setting. Also, the monitoring unit 401 may aperiodically judge the state of each reflecting element based on an instruction from the base station 100. When the monitoring unit 401 detects a defective element, it notifies the reporting unit 402.

[0045] The report unit 402 reports information on the defective elements to the base station 100. The report unit 402 may report when a set condition is satisfied based on the report setting notified by the base station 100. For example, the report setting indicates a threshold value of the defective rate as a condition for executing the report. As an example, the report unit 402 counts the number of defective elements notified by the monitoring unit 401 and determines whether the defective rate exceeds the threshold value. If the defective rate exceeds the threshold value, the report unit 402 reports, for example, information identifying the defective elements to the base station 100. The information identifying the defective rate may be information indicating the position of the defective element on the reflector. The acquisition 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 report setting, and the like. The acquisition 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.

[0046] The notification unit 405 notifies the base station 100 of the stop of reporting, the stop of control of the reflection device, and the like. For example, if the reporting setting notified from the base station 100 includes a condition for stopping the reporting of information on the defective element, 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 the reporting has been met. Note that, if the condition for stopping the reporting is met, the reporting unit 402 does not report to the base station 100 even if the condition for reporting information on the defective element is met thereafter. On the other hand, for example, if the reporting setting notified from the base station 100 includes a condition for stopping the 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 the control of the reflection device 120. Upon receiving this notification, the notification unit 405 notifies the base station 100 that the condition for stopping the control of the reflection device has been met. The condition for stopping the control of the reflection device may be a condition for turning off the power supply of the reflection device. In this case, the reflection device control unit 404 may turn off the power supply of the reflection device 120 when this condition is satisfied, and the notification unit 405 may notify the base station 100 that the condition for turning off the power supply of the reflection device is satisfied.

[0047] 5 is a diagram showing an example of a functional configuration of the base station 100. The base station 100 has, as its functions, for example, an acquisition unit 501, a reflection 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 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 limited to this, and for example, dedicated hardware for realizing each function may be prepared.

[0048] The acquisition unit 501 acquires information on the defective element from the control device 130. The information on the defective element includes, for example, information for identifying the defective element. The acquisition unit 501 notifies the acquired information on the defective element to the reflection element setting unit 502. The reflection element setting unit 502 determines a reflection phase to be set for each reflection element of the reflection device 120. The reflection element setting unit 502 may determine a reflection phase to be set for each reflection element for each reflection pattern. When the information on the defective element is received from the acquisition unit 501, the reflection element setting unit 502 determines whether or not to change the reflection phase. For example, the reflection 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 the reflection elements are operating normally. The reflection element setting unit 502 may determine to change the reflection phase when the difference exceeds a threshold value. The reflection element setting unit 502 notifies the control device 130 of the changed reflection element setting.

[0049] The monitoring setting unit 503 and the report setting unit 504 generate monitoring settings and report settings for controlling the monitoring process and report process executed by the control device 130, respectively, and notify the control device 130. The monitoring settings may include a period for the control device 130 to determine the state of the reflecting element, etc. Furthermore, the report settings may include a condition for the control device 130 to report a defective element, etc. Furthermore, the report settings may include a condition for the control device 130 to stop the report process or a condition for stopping the control of the reflecting device. When the condition for stopping the report process or the condition for stopping the control of the reflecting device is satisfied, the acquisition unit 501 receives a notification of the report stop or a notification of the control of the reflecting device from the control device 130. When the base station 100 receives 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.

[0050] (Processing flow) Next, an example of the flow of the process executed in the wireless communication system will be described. Note that since the details of the process are as described above, an overview of the process flow will be given here, and the details will not be repeated.

[0051] FIG. 6 shows an example of a process flow in which the control device 130 reports a defective element detected by the base station 100 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 a pattern ID and a 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 communicating with the terminal 110 (S601), and notifies the control device 130 of a 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 showing 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 occurs in the reflecting device 120 (S605). The control device 130 periodically monitors the reflecting elements (S606) and detects defective elements by judging the state of each reflecting element (S607). The control device 130 reports information on the detected defective elements to the base station 100 (S608). As described above, the control device 130 may report information on the defective elements when conditions are met according to the report setting notified in advance by the base station 100. The base station 100 generates a new reflecting element setting based on the reported information on the defective elements (S609). The method of generating the reflecting element setting may be any of the above-mentioned methods, 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 and 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 be changed based on the notified information about the defective element.

[0052] FIG. 7 shows an example of a flow of processing when the control device 130 executes monitoring processing and reporting processing of a defective element according to the monitoring setting and the reporting setting 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 condition for the control device 130 to report a defective element, and generates the monitoring setting and the reporting setting (S701). For example, it is assumed 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 in the reporting setting. The base station 100 notifies the generated monitoring setting and the reporting setting to the control device 130 (S702). Here, it is assumed that a defective element occurs in the reflecting device 120 (S703). The control device 130 periodically judges the state of each reflecting element of the reflecting device 120 according to the monitoring setting notified from the base station 100, and detects a defective element (S704). Here, for example, if the defective rate calculated by the control device 130 exceeds the first threshold, the condition indicated in the report setting is satisfied (S705), and the control device 130 reports information on the defective element to the base station 100 (S706). The flow of processing from S707 to S710 is the same as S609 to S612 in FIG. 6, and therefore the description will be omitted. Next, assume that a defective element occurs in the reflection device 120 (S711). The control device 130 continues to monitor the defective element even after changing the reflection phase of each reflection element. If the control device 130 detects a defective element (S712), and for example, the defective rate calculated by the control device 130 exceeds the second threshold 0.2 indicated in the report setting (S713), the control device 130 reports information on the defective element to the base station 100 (S714). In this way, it is possible to control the monitoring of the reflection element and the reporting of the defective element by the control device 130 based on the monitoring setting and report setting generated by the base station 100.

[0053] FIG. 8 shows an example of a process flow when the control device 130 stops reporting information about a defective element or stops control of the reflection device 120. First, the base station 100 determines a condition for the control device 130 to stop reporting information about a defective element or a condition for the control device 130 to stop control of the reflection device 120 (S801). These conditions may be the same or different from each other. 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 notification of the condition may be included in the report setting notified from the base station 100 to the control device 130. Here, it is assumed that a defective element occurs in the reflection device 120 (S803). The control device 130 periodically determines the state of each reflection element and detects a defective element (S804). Here, for example, if the defect rate calculated by the control device 130 exceeds a predetermined threshold, the set condition is satisfied (S805), and the control device 130 notifies the base station 100 that the condition is satisfied (S806). The control device 130 also stops the control of the reflection device 120 and performs control to turn off the power supply of the reflection device 120 (S807). Then, the control device 130 notifies the base station 100 that the control of the reflection device 120 has been stopped or that the power supply of the reflection device 120 has been turned off (S808). The reflection device 120 turns off its own power supply in accordance with the control from the control device 130 (S809). In this way, it is possible to stop the reporting of information on defective elements in the control device 130 and the control of the reflection device 120 based on the condition set by the base station 100.

[0054] As described above, according to this embodiment, the control device 130 autonomously monitors the state of the reflecting element of the reflecting device 120 and reports information on defective elements to the base station. Furthermore, the base station specifies the reflection phase to be set in the reflecting element based on the reported information on 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.

[0055] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the invention. [Explanation of symbols]

[0056] 100: base station, 110: terminal, 120: reflector, 130: control device

Claims

1. A monitoring device that monitors a reflecting device that reflects radio waves transmitted from a base station using a reflector that includes a plurality of reflecting elements, A monitoring means for monitoring a state of the reflecting element constituting the reflector; a notification means for notifying the base station of detection information of a defective element, which is a reflection element that does not operate normally, when the monitoring means detects the defective element. A monitoring device comprising:

2. The detection information includes identification information capable of identifying the defective element.

2. The monitoring device according to claim 1.

3. The specific information is an identifier of the defective element.

3. The monitoring device according to claim 2.

4. The specific information is a position of the defective element on the reflector.

3. The monitoring device according to claim 2.

5. the detection information includes a number of the defective elements or a defect rate which is a ratio of the defective elements to the reflecting elements constituting the reflecting plate; 2. The monitoring device according to claim 1.

6. The notification means notifies the base station of the detection information by 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.

6. A monitoring device according to claim 1,

7. A control method executed by a monitoring device that monitors a reflection device that reflects radio waves transmitted from a base station using a reflector configured with a plurality of reflection elements, comprising: a monitoring step of monitoring a state of the reflective element constituting the reflector; a notification step of notifying the base station of detection information of a defective element, which is a reflection element that does not operate normally, when the monitoring step detects the defective element. A control method comprising:

8. A computer provided in a monitoring device that monitors a reflecting device that reflects radio waves transmitted from a base station using a reflector configured with a plurality of reflecting elements, monitoring a state of the reflecting elements constituting the reflector; When a defective element, which is a reflection element that does not operate normally, is detected, detection information of the defective element is notified to the base station. Program for.

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