Wireless communication system, wireless communication device, wireless communication method, and wireless communication program

Abstract

The present disclosure relates to a wireless communication system, a wireless communication device, a wireless communication method, and a wireless communication program. The wireless communication system comprises: an information processing unit; a base station; a plurality of terminals that wirelessly communicate with the base station; and a plurality of relay devices that can relay wireless communication. The information processing unit is configured so as to implement a process for creating a radio wave map on the basis of position information and quality level information pertaining to the terminals. The base station is configured so as to implement: a process for determining, on the basis of the radio wave map, whether communication quality levels pertaining to all destination terminals are greater than a threshold serving as a reference quality level; a process for turning off power sources of the relay devices when all of the communication quality levels are greater than the threshold; and a process for, when any of the communication quality levels is equal to or lower than the threshold, allocating a relay device to an area having a low communication quality level and turning on the power source of the allocated relay device.

Description

Wireless communication system, wireless communication device, wireless communication method, and wireless communication program

[0001] The present disclosure relates to a wireless communication system, a wireless communication device, a wireless communication method, and a wireless communication program.

[0002] There is known a technology for improving communication quality in places where the line of sight is blocked by forming a wireless propagation path using a relay device. For example, Non-Patent Document 1 discloses a technology that uses RISs (Reconfigurable Intelligent Surfaces), which is a type of relay device.

[0003] A repeater is a reflector that can dynamically control beams and relay signals sent from a transmitter. By controlling the beam of the repeater based on the location information of the destination terminal, it is possible to form a wireless propagation path that follows the movement of the terminal, ensuring stable communication quality.

[0004] E. Basar, M. Di Renzo, J. De Rosny, M. Debbah, M. -S. Alouini and R. Zhang, "Wireless Communications Through Reconfigurable Intelligent Surfaces," in IEEE Access, vol. 7, pp. 116753-116773, 2019

[0005] However, in the case of control based on location information, signals are always relayed even when the communication quality of the terminal can be ensured without relaying the signals. In other words, there is a problem in that the relay device operates even when it is not actually necessary, resulting in more power consumption than necessary.

[0006] In order to solve the above-mentioned problems, a first object of the present disclosure is to provide a wireless communication system that can prevent power from being consumed more than necessary.

[0007] A second object of the present disclosure is to provide a wireless communication device that can prevent power from being consumed more than necessary.

[0008] A third object of the present disclosure is to provide a wireless communication method that can prevent power from being consumed more than necessary.

[0009] A fourth object of the present disclosure is to provide a wireless communication program that can prevent power from being consumed more than necessary.

[0010] A first aspect of the present disclosure is preferably a wireless communication system comprising an information processing unit, a base station, a plurality of terminals that communicate wirelessly with the base station, and a plurality of relay devices that can relay the wireless communication, wherein the information processing unit is configured to perform a process of creating a radio wave map based on location information and quality information of the terminals, and the base station is configured to perform a process of determining, based on the radio wave map, whether the communication quality of all destination terminals is greater than a threshold value that serves as a reference quality, a process of turning off the power of the relay device if all communication qualities are greater than the threshold value, and a process of assigning a relay device to an area with poor communication quality and turning on the power of the assigned relay device if any communication quality is below the threshold value.

[0011] Furthermore, a second aspect of the present disclosure is preferably a wireless communication device that wirelessly communicates with a terminal and controls a relay device used for wireless communication, and is configured to perform the following processes: determining whether the communication quality of all destination terminals is greater than a threshold value that serves as a reference quality, based on a radio wave map created based on location information and quality information of the terminals; turning off the power of the relay device if all communication qualities are greater than the threshold value; and assigning a relay device to an area with poor communication quality and turning on the power of the assigned relay device if any communication quality is below the threshold value.

[0012] Furthermore, a third aspect of the present disclosure is preferably a wireless communication method for controlling a relay device that can relay wireless communication between a base station and a terminal, the wireless communication method comprising: creating a radio wave map based on location information and quality information of the terminal; determining, based on the radio wave map, whether the communication quality of all destination terminals is greater than a threshold value that serves as a reference quality; turning off the power of the relay device if all communication qualities are greater than the threshold value; and assigning a relay device to an area with poor communication quality and turning on the power of the assigned relay device if any communication quality is equal to or less than the threshold value.

[0013] Furthermore, a fourth aspect of the present disclosure is a wireless communication program to be executed by a wireless communication device that has a processor and a memory, communicates wirelessly with a terminal, and controls a relay device used for the wireless communication, the wireless communication program being stored in the memory and computer-readable, and including a program that causes the processor to perform the following processes: determining whether the communication quality of all destination terminals is greater than a threshold value that serves as a reference quality based on a radio wave map created based on location information and quality information of the terminals; turning off the power of the relay device if all communication qualities are greater than the threshold value; and assigning a relay device to an area with poor communication quality and turning on the power of the assigned relay device if any communication quality is below the threshold value.

[0014] According to the first to fourth aspects of the present disclosure, it is possible to prevent power from being consumed more than necessary.

[0015] FIG. 1 is a diagram showing a wireless communication system according to a first embodiment of the present disclosure. FIG. 2 is a diagram showing a wireless communication system according to a comparative example. FIG. 3 is a block diagram showing a configuration of a wireless communication system according to a first embodiment of the present disclosure. FIG. 4 is a block diagram showing a configuration of a wireless communication system according to a first embodiment of the present disclosure. FIG. 5 is a diagram showing an example hardware configuration of a base station according to a first embodiment of the present disclosure. FIG. 6 is a diagram showing an image of transmission of a control signal according to a first embodiment of the present disclosure. FIG. 7 is a flowchart showing relay control according to a first embodiment of the present disclosure. FIG. 8 is a block diagram showing a configuration of a wireless communication system according to a second embodiment of the present disclosure. FIG. 9 is a block diagram showing a configuration of a wireless communication system according to a third embodiment of the present disclosure.

[0016] 1 is a diagram showing a wireless communication system according to a first embodiment of the present disclosure. The wireless communication system 100 includes a base station 2. The base station 2 is a transmitter that controls the propagation path of a signal to be transmitted to a terminal 6 based on a radio wave map created by an information processing unit 4. That is, the base station 2 has a function of wirelessly communicating with the terminal 6 and a function of controlling a relay device 8 used for wireless communication by transmitting a control signal. The terminal 6 is also mobile.

[0017] First, the base station 2 acquires location information and quality information from a plurality of terminals 6 under its control, and transmits the information to the information processing unit 4. The quality information is information relating to communication quality, such as the strength of received power such as RSSI and RSRQ, noise indices such as RSRP and SINR, and throughput.

[0018] It is assumed that the terminal 6 communicates using a low frequency band, but this is not limiting, and the terminal 6 may communicate using a high frequency band, a licensed band, or an unlicensed band. Furthermore, if the terminal 6 does not have a function for acquiring location information, the location information of the terminal 6 may be acquired by another sensing device and transmitted to the base station 2.

[0019] The information processing unit 4 creates a radio wave map based on the received information. The radio wave map is a map that visualizes the communication quality status for each area. The radio wave map is created planarly or spatially by interpolating acquired data, making it possible to estimate the quality of the wireless space. Note that while FIG. 1 shows a radio wave map based on Received Signal Power as an example, the present invention is not limited to this. For example, a radio wave map may be created based on the strength of received power such as RSSI and RSRQ, noise indices such as RSRP and SINR, or throughput.

[0020] The base station 2 determines whether relaying is necessary when transmitting a signal based on the radio wave map. If it determines that relaying is necessary, it performs relay control by transmitting a control signal to a relevant relay device 8 from among the multiple relay devices 8. Details of relay control will be described later.

[0021] The relay device 8 is a reflector that can relay signals transmitted from the base station 2 by performing dynamic beam control, and operates by on / off control and beam control. Based on the control signal received from the base station 2, the relay device 8 performs power on / off control for the relay device 8 and optimizes relay resources. Examples of relay resources include beam intensity, amplification factor, and the number of elements used.

[0022] 2 is a diagram showing a wireless communication system according to a comparative example. The wireless communication system 500 according to the comparative example differs from the present embodiment in that relay control by the base station 2 is performed based on location information.

[0023] The base station 2 performs relay control based on the location information of the terminal 6. This relay control is performed without considering the communication quality before and after the relay control. Therefore, the base station 2 always relays signals even when the communication quality of the terminal can be ensured without relaying the signals. As a result, the base station 2 operates the relay device 8 even when it is not actually necessary, resulting in a problem of consuming more power than necessary. The present disclosure solves this problem.

[0024] Fig. 3 is a block diagram showing the configuration of a wireless communication system according to the present disclosure. Processing commonly performed by the wireless communication system according to the present disclosure will be described in more detail with reference to Fig. 3. The wireless communication system according to the present disclosure includes a plurality of relay devices 8 and terminals 6. Each of the plurality of relay devices 8 and terminals 6 has the same function.

[0025] First, we will explain the route by which the base station 2 acquires location information from multiple terminals 6. The terminal positioning unit 62 acquires the location information of the terminals 6 and transmits it to the positioning signal generation unit 64. The positioning signal generation unit 64 transmits the acquired information to the information acquisition unit 24. The information acquisition unit 24 transmits the acquired location information to the data acquisition unit 42.

[0026] The data acquisition unit 42 transmits the information acquired from the multiple terminals 6 to the database unit 44. The database unit 44 stores all the acquired position information.

[0027] Next, we will explain the route by which the base station 2 acquires quality information from multiple terminals 6. The signal generator 66 generates a signal based on the quality information acquired by the terminal 6 and transmits it to the signal transmitter / receiver 68. The signal transmitter / receiver 68 transmits the received signal to the signal transmitter / receiver 25. This transmission is performed via the reflector 86 or directly.

[0028] The signal transmitting / receiving unit 25 transmits signals acquired from the multiple terminals 6 to the quality acquiring unit 26. The quality acquiring unit 26 acquires quality information based on the signals and transmits it to the data acquiring unit 42.

[0029] The data acquisition unit 42 transmits the acquired information to the database unit 44. The database unit 44 stores all the acquired quality information.

[0030] Next, the route by which the base station 2 acquires a radio wave map will be described. The data processing unit 46 acquires the location information and quality information stored in the database unit 44, and creates a radio wave map based on this information. When updating the radio wave map in the second or subsequent radio wave map creation, the data processing unit 46 acquires the location information, quality information, and already-created radio wave maps stored in the database unit 44, and creates a radio wave map based on this information. The data processing unit 46 then transmits the created radio wave map to the database unit 44.

[0031] The database unit 44 stores the received radio wave map. The control unit 21 of the base station 2 can access the database unit 44 to obtain the radio wave map.

[0032] Next, we will explain the route that the base station 2 controls relaying based on the radio wave map. The control unit 21 determines whether relaying is necessary when transmitting a signal based on the radio wave map. For example, it checks the communication quality of the areas where multiple terminals 6, the destinations of the signal, are located, and determines that relaying is necessary if there is an area where the quality is worse than a reference quality, but determines that relaying is not necessary if the communication quality of all areas is equal to or higher than the reference quality.

[0033] If it is determined that relaying is necessary, the appropriate relay device 8 is assigned in order from the area with the worst communication quality. Then, the control information required for relay control is calculated and transmitted to the control signal generation unit 22. The control signal generation unit 22 generates a control signal based on the received information and transmits it to the control signal communication unit 23.

[0034] The control signal communication unit 23 transmits the received control signal to the control signal communication unit 82 of the assigned relay device 8. The line for transmitting the control signal may be wired or wireless, and any method may be used.

[0035] The control signal communication unit 82 transmits the received control signal to the weight setting unit 84. The weight setting unit 84 sets parameters for optimizing relay resources based on the received control signal. The weight setting unit 84 then transmits the set parameters to the reflecting unit 86. The reflecting unit 86 optimizes the resources based on the received parameters, thereby forming an appropriate wireless propagation path between the base station 2 and the corresponding terminal 6.

[0036] The relay devices 8 may each be provided with a power generation unit 88 to generate their own power as a power source. The wireless communication system 100 may also be provided with an external sensor that acquires information.

[0037] 4 is a block diagram showing a configuration of a wireless communication system according to the first embodiment of the present disclosure. In the wireless communication system 100, an information processing unit 4a is accommodated in a base station 2a. That is, there are as many information processing units 4a as there are base stations 2a.

[0038] The information processing unit 4a includes the control unit 21. The processing performed by the information processing unit 4a in this case will be described below. First, the data processing unit 46 creates a radio wave map. At this time, the data processing unit 46 calculates necessary control information based on the data map and transmits it to the database unit 44. This control information is, for example, control information that activates relaying when the communication quality at the terminal 6 is equal to or lower than the threshold Pth, and control information that turns off relaying when the communication quality at the terminal 6 is higher than the threshold Pth.

[0039] The database unit 44 stores the received control signal. The control unit 21 can acquire the control information by accessing the database unit 44. The control unit 21 transmits the acquired control information to the control signal generation unit 22.

[0040] In this way, when the information processing unit 4a is accommodated in the base station 2a, the base station 2a can perform local control using only the multiple relay devices 8 and multiple terminals 6 under its control. In other words, the base station 2a can easily perform individual control, such as setting a threshold value for each base station.

[0041] 5 is a diagram illustrating an example of a hardware configuration of a base station according to the first embodiment of the present disclosure. Each function of the base station 2 may be partially or entirely configured by hardware such as a programmable logic device (PLD) or a field programmable gate array (FPGA), or may be configured as a program executed by a processor such as a CPU.

[0042] For example, the base station 2 can be realized using a computer and a program, and the program can be recorded on a storage medium or provided via a network.

[0043] 5, the base station 2 has an input unit 200, an output unit 201, a communication unit 202, a CPU 203, a memory 204, and an HDD 205 connected via a bus 206, and functions as a computer. The base station 2 is also capable of inputting and outputting data to and from a computer-readable storage medium 207.

[0044] The input unit 200 is, for example, a keyboard and a mouse, etc. The output unit 201 is, for example, a display device such as a display.

[0045] The communication unit 202 is, for example, a communication interface that communicates with a wireless device to be controlled.

[0046] The CPU 203 controls each component of the base station 2 and performs predetermined processing, etc. The memory 204 and HDD 205 store data, etc.

[0047] The storage medium 207 is capable of storing programs and the like that cause the base station 2 to execute the functions of the base station 2. Note that the architecture that configures the base station 2 is not limited to the example shown in FIG.

[0048] 6 is a diagram illustrating an image of transmission of a control signal according to the first embodiment of the present disclosure. The control signal communication unit 23 transmits the control signal transmitted from the control unit 21 to the assigned relay device 8. This control signal includes information linking a parameter for optimizing relay resources with a parameter indicating the assigned relay device 8. The parameter indicating the assigned relay device 8 is, for example, an ID linked to each relay device 8.

[0049] For example, the control signal communication unit 23 transmits a control signal to the relay device 8 indicated by the ID included in the control signal. This process allows only the assigned relay device 8 to optimize relay resources, thereby forming an appropriate wireless propagation path between the base station 2 and the corresponding terminal 6.

[0050] Alternatively, the control signal communication unit 23 broadcasts a control signal transmitted from the control unit 21. The broadcast control signal includes area information to be controlled. When the area information included in the control signal is an area associated with the relay devices 8, the relay devices 8 optimize relay resources using parameters included in the control signal. When the received control signal includes an ID associated with the relay devices 8, the relay devices 8 optimize relay resources using parameters associated with the ID.

[0051] 7 is a flowchart illustrating relay control according to the first embodiment of the present disclosure. First, in step 100, the base station 2 sets a threshold Pth that serves as a reference quality. The threshold Pth is a reference quality that is used as an index when determining whether relaying is necessary, and is, for example, a specific threshold of RSSI.

[0052] The threshold value Pth may be a preset unique value. The preset unique value may be, for example, a value registered as a default value at the time of shipping from the factory. In this case, the process of step 100 is not necessary.

[0053] Next, in step 102, the base station 2 determines whether the communication quality Pr of all destination terminals 6 is greater than the threshold value Pth. This determination is made by the base station 2 based on a radio wave map. If all communication qualities Pr are greater than the threshold value Pth, the process proceeds to step 103. If any communication quality Pr is equal to or less than the threshold value Pth, the process proceeds to step 104.

[0054] In step 103, the base station 2 turns off the power to the relay device 8, completing all processing. Turning off the power may be achieved by the base station 2 sending a control signal to the relay device 8 instructing it to turn off the power, or by doing nothing if it is known that the power to the relay device 8 is off.

[0055] In step 104, the number n of areas where the communication quality Pr is equal to or less than the threshold Pth and the number k of relay devices that can be assigned are detected. Next, in step 106, it is determined whether n=0 or k=0. If n=0 or k=0 is not true, the process proceeds to step 108. If n=0 or k=0 is true, the process proceeds to step 114.

[0056] In step 108, area X, which is the area with the worst communication quality, is selected from among the n areas whose communication quality Pr is equal to or less than the threshold value Pth.

[0057] Next, in step 110, a relay device 8 is assigned from among the k available relay devices 8 to improve communication quality in area X. The relay device 8 to be assigned may be, for example, the relay device 8 located closest to area X. Alternatively, the relay device 8 to be assigned may be, for example, a relay device 8 associated with area X based on its coverage area, location information, etc.

[0058] If there are multiple relay devices 8 applicable to area X, at least one relay device 8 that can improve communication quality the most is assigned. By this process, if not all relay devices 8 applicable to area X are assigned, some of the relay devices 8 can be turned off, thereby reducing power consumption.

[0059] Next, in step 112, the numbers n and k are decremented by 1, and the process returns to step 104. In this manner, steps 104 to 112 are repeated until the number of assignable relay devices 8 becomes zero, or until the number of areas where communication quality cannot be ensured becomes zero.

[0060] In step 114, the base station 2 notifies the relay device 8 of the control content by transmitting a control signal, and all processing is completed. This control signal includes a signal for turning on the power of the assigned relay device 8.

[0061] As described above, according to this embodiment, if communication quality can be ensured for all terminals 6 without signal relay, the relay device 8 can be turned off. Furthermore, according to this embodiment, even if there is a terminal 6 for which communication quality cannot be ensured, only the necessary relay devices 8 need to be turned on, and unnecessary relay devices 8 can be kept in the off state. In other words, it is possible to prevent power from being consumed more than necessary.

[0062] Furthermore, according to the aspects of this embodiment, by controlling a plurality of relay devices 8 simultaneously, the communication quality of the entire wireless communication system can be improved compared to when only one relay device 8 is controlled.

[0063] The relay control described above is performed periodically. The radio wave map used in the first relay control is created based on quality information when all of the relay devices 8 are powered off. In the second and subsequent relay control, a radio wave map created again with all of the relay devices 8 powered off is used, so a process of powering off all of the relay devices 8 in advance may be added.

[0064] Alternatively, if at least one relay device 8 was powered on in the immediately preceding process, instead of using the radio wave map re-created with the power of the relevant relay device 8 turned on, the threshold used in step 102 may be changed. For example, a new threshold Pth' may be set that adds a safety margin to the threshold Pth, and step 102 may be changed to a process of determining whether the communication quality P is greater than the threshold Pth'.

[0065] By adding the above-described process, when the reference quality of the terminal 6 is met due to a change over time in the location information or communication quality without using the relay device 8 that was turned on until the line, it is possible to turn off the power of the unnecessary relay device 8. In other words, it is possible to prevent power from being consumed more than necessary.

[0066] 8 is a block diagram showing a configuration of a wireless communication system according to a second embodiment of the present disclosure. The wireless communication system 110 differs from the wireless communication system 100 in that the information processing unit 4 is not included in the base station 2.

[0067] The information processing unit 4 included in the wireless communication system 110 is assumed to be located on a network such as a cloud. When the information processing unit 4 is located on a network, one information processing unit 4 may have a function of collecting information about multiple base stations 2 and multiple relay devices 8.

[0068] In this way, when the information processing unit 4 is not included in the base station 2, the processing power can be reduced by the amount required for creating the radio wave map. As a result, power consumption can be reduced. Furthermore, since the components of the base station 2 can be minimized, it can be easily introduced into the small base station of the present disclosure.

[0069] Furthermore, as described above, the information processing unit 4 on the network can collect information about multiple base stations 2. Therefore, even at the edge of an area where multiple base stations 2 are located, that is, at the so-called cell edge, the information processing unit 4 can create a radio wave map with higher accuracy by reflecting data acquired from adjacent base stations.

[0070] Regarding the control information, when it is determined based on the radio wave map that relaying is necessary, the control unit 21 calculates the control information necessary for relay control, as described above, but the present invention is not limited to this. For example, when the data processing unit 46 creates the radio wave map, it may assume positions to which the terminal 6 may move and calculate the necessary control information.

[0071] In the above case, the control unit 21 acquires the control information together with the radio wave map. If the control unit 21 determines that relaying is necessary, it transmits the acquired control information to the control signal generation unit 22.

[0072] As described above, according to the aspect of this embodiment, when the communication quality of the terminal 6 can be ensured without signal relay, the relay device 8 can be turned off. In other words, it is possible to prevent power from being consumed more than necessary.

[0073] 9 is a block diagram showing the configuration of a wireless communication system according to a third embodiment of the present disclosure. The wireless communication system 120 differs from the wireless communication system 110 in that it acquires information for creating a radio wave map from a source other than the terminal 6.

[0074] The wireless communication system 120 includes an external sensor 9. The external sensor 9 is, for example, a positioning device, such as a camera, that can acquire location information of the terminal 6. The external sensor 9 transmits the acquired location information of the terminal 6 to the information acquisition unit 24. The data processing unit 46 creates a radio wave map based on this location information.

[0075] The location information of the terminal 6 may be location information that the data processing unit 46 statistically estimates from the location information of the terminal 6 up to that point, or location information related to the uplink estimated by the base station 2 may be used. Furthermore, the quality information of the terminal 6 may also be quality information related to the uplink estimated by the base station 2.

[0076] As described above, according to this aspect of the present embodiment, by using a radio wave map created based on information acquired from sources other than the terminal 6, it is possible to prevent unnecessary power consumption. In other words, the terminal 6 does not need to have a mechanism for acquiring information for creating the radio wave map, which makes it possible to reduce the weight or simplify the terminal 6. Alternatively, even if the terminal 6 only has a partial mechanism for acquiring information for creating the radio wave map, a more accurate radio wave map can be created by utilizing some of the acquired information in creating the radio wave map.

[0077] Fourth Embodiment A wireless communication system according to a fourth embodiment differs from the first to third embodiments in that a radio wave map is created taking into consideration line-of-sight and non-line-of-sight (LOS and NLOS) conditions.

[0078] The radio wave map according to the fourth embodiment is created based on information on the orientation of the terminal 6 and the shielding status, in addition to location information and quality information. The shielding status refers to the shielding status of the terminal 6 due to, for example, people, other terminals, buildings, etc. present around the terminal 6. This information may be acquired by the terminal 6, may be acquired by an external sensor 9, or may be estimated by the base station 2. By adding this information, a radio wave map can be created that takes into account line-of-sight and non-line-of-sight conditions.

[0079] The control unit 21 determines whether relaying is necessary when transmitting a signal based on a radio wave map that takes into account line-of-sight and non-line-of-sight conditions. If it determines that relaying is necessary, it calculates control information necessary for relay control and transmits it to the control signal generation unit 22. The subsequent processing is the same as in the first embodiment.

[0080] As described above, according to the present embodiment, by using a radio wave map that takes into account line-of-sight and non-line-of-sight conditions, it is possible to prevent unnecessary power consumption. In other words, it is possible to realize relay control that is more suited to the actual conditions of the terminal 6.

[0081] 2 Base station 2a Base station 4 Information processing unit 4a Information processing unit 6 Terminal 8 Relay device 100 Wireless communication system 110 Wireless communication system 120 Wireless communication system 204 Memory 500 Wireless communication system

Claims

1. A wireless communication system comprising an information processing unit, a base station, a plurality of terminals that communicate wirelessly with the base station, and a plurality of relay devices that can relay the wireless communication, wherein the information processing unit is configured to perform a process of creating a radio wave map based on location information and quality information of the terminals, and the base station is configured to perform the following processes: determine, based on the radio wave map, whether the communication quality of all of the destination terminals is higher than a threshold value that serves as a reference quality; turn off the power of the relay device if all of the communication qualities are higher than the threshold value; and assign the relay device to an area with poor communication quality and turn on the power of the assigned relay device if any of the communication qualities is equal to or lower than the threshold value.

2. A wireless communication device that wirelessly communicates with a terminal and controls a relay device used for said wireless communication, and is configured to perform the following processes: determining whether the communication quality of all of the destination terminals is higher than a threshold value that serves as a reference quality, based on a radio wave map created based on location information and quality information of said terminals; turning off the power of said relay device if all of said communication qualities are higher than said threshold; and allocating said relay device to an area with poor communication quality and turning on the power of said allocated relay device if any of said communication qualities is equal to or lower than said threshold.

3. A wireless communication method for controlling a relay device that can relay wireless communication between a base station and a terminal, comprising: creating a radio wave map based on location information and quality information of the terminal; determining, based on the radio wave map, whether the communication quality of all of the destination terminals is higher than a threshold value that serves as a reference quality; turning off the power of the relay device if all of the communication qualities are higher than the threshold value; and assigning the relay device to an area where the communication quality is poor and turning on the power of the assigned relay device if any of the communication qualities is below the threshold value.

4. A wireless communication program to be executed by a wireless communication device that has a processor and memory, that communicates wirelessly with a terminal, and that controls a relay device used for said wireless communication, said wireless communication program being stored in said memory and computer-readable, and including a program that causes said processor to execute the following processes: determining whether the communication quality of all of said destination terminals is higher than a threshold value that serves as a reference quality based on a radio wave map created based on location information and quality information of said terminals; turning off the power of said relay device if all of said communication qualities are higher than said threshold; and assigning said relay device to an area where communication quality is poor and turning on the power of said assigned relay device if any of said communication qualities is equal to or lower than said threshold.

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