Wireless communication device and wireless communication method

Abstract

The present disclosure relates to a wireless communication device and a wireless communication method. This wireless communication device wirelessly communicates with a terminal and controls a plurality of relay devices used for wireless communication. The wireless communication device is configured to execute: a process for extracting a relay device capable of improving communication quality for the terminal by performing beam formation; a process for acquiring the amount of power remaining in the extracted relay device; a process for selecting a relay device having the largest amount of remaining power and for causing the selected relay device to perform beam formation; and a process for turning off the power supply of a relay device that has not been selected from among the plurality of relay devices.

Description

Wireless Communication Device and Wireless Communication Method

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

[0002] There is known a technique for improving communication quality in a location that is out of sight due to shielding or the like by forming a wireless propagation path using a relay device. For example, Non-Patent Document 1 discloses a technique using RISs (Reconfigurable intelligent surfaces), which is a type of relay device.

[0003] The relay device is composed of a relay mechanism, a control controller, and a power source. The relay device controls the relay mechanism and the control controller using the power supplied from the power source. The power source is, for example, a battery.

[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 above-described technique, when a plurality of relay devices are installed, depending on the selection of the relay method, there may be a bias in the relay devices used. In that case, there is also a bias in the power consumption of each relay device, so there is also a bias in the remaining battery level of each relay device. As a result, there is a problem that battery depletion occurs only in some of the relay devices, and there may be a time period or period during which they cannot be used.

[0006] In order to solve the above problems, a first object of the present disclosure is to provide a wireless communication device that can extend the operating time of all relay devices when a plurality of relay devices are installed.

[0007] A second object of the present disclosure is to provide a wireless communication method that can extend the operating time of all relay devices when a plurality of relay devices are installed.

[0008] A first aspect of this disclosure is a wireless communication device that wirelessly communicates with a terminal and controls a plurality of relay devices used for wireless communication, wherein the wireless communication device is configured to perform the following processes: extracting relay devices that can improve the communication quality at the terminal by beamforming; acquiring the remaining power of the extracted relay devices; selecting the relay device with the largest remaining power and causing the selected relay device to beamform; and turning off the power of the relay devices that were not selected among the plurality of relay devices.

[0009] Furthermore, a second aspect of the present disclosure is preferably a wireless communication method for controlling relay devices capable of relaying wireless communication between a base station and a terminal, comprising: extracting relay devices capable of improving the communication quality at the terminal by beamforming; obtaining the remaining power of the extracted relay devices; selecting the relay device with the largest remaining power and causing the selected relay device to beamform; and turning off the power of the relay devices that were not selected among a plurality of relay devices.

[0010] According to the first and second aspects of this disclosure, when multiple relay devices are installed, the operating time of all relay devices can be extended.

[0011] This is a diagram showing a wireless communication system according to Embodiment 1 of the present disclosure. This is a block diagram showing the configuration of the wireless communication system according to the present disclosure. This is a block diagram showing the configuration of the wireless communication system according to Embodiment 1 of the present disclosure. This is a diagram showing an image of the transmission of a control signal according to Embodiment 1 of the present disclosure. This is a diagram showing an example of the hardware configuration of a base station according to Embodiment 1 of the present disclosure. This is a flowchart showing relay control according to Embodiment 1 of the present disclosure. This is a diagram showing a wireless communication system according to a comparative example. This is a flowchart showing relay control according to Embodiment 2 of the present disclosure. This is a diagram showing an image of the transmission of a control signal according to Embodiment 3 of the present disclosure. This is a diagram showing an image of the transmission of a control signal according to Embodiment 4 of the present disclosure. This is a diagram showing an image of the transmission of a control signal according to Embodiment 5 of the present disclosure. This is a diagram showing an image of the transmission of a control signal according to Embodiment 6 of the present disclosure.

[0012] Each embodiment will be described with reference to the drawings. The same or corresponding components will be denoted by the same reference numerals, and repetition of the description may be omitted.

[0013] Embodiment 1 Figure 1 is a diagram showing a wireless communication system according to Embodiment 1 of the present disclosure. The wireless communication system 100 includes a base station 2. The base station 2 has an information processing unit 4.

[0014] Base station 2 is a transmitter that controls the propagation path of signals transmitted to terminal 6 based on the selection of information processing unit 4. In other words, base station 2 has the function of wirelessly communicating with terminal 6 and the function of controlling the relay device 8, which will be described later, by transmitting control signals. Terminal 6 is also mobile.

[0015] First, base station 2 acquires positioning information and quality information from the terminal 6 under its control and transmits it to information processing unit 4. Positioning information is, for example, the location information of terminal 6. Quality information is information related to communication quality, such as the strength of received power like RSSI and RSRQ, noise indices like RSRP and SINR, throughput, or received power. The information that base station 2 acquires from terminal 6 may also include channel information used when base station 2 and terminal 6 perform wireless communication.

[0016] While it is assumed that terminal 6 communicates using a low-frequency band, it is not limited to this and may also communicate using a high-frequency band, licensed band, or unlicensed band. When terminal 6 communicates using a low-frequency band, it is less susceptible to interference from shielding, etc., compared to when wireless communication is performed using a high-frequency band, etc. As a result, when communication is performed using a low-frequency band, there is an advantage in that the base station 2 can easily acquire the location information of terminal 6. Also, if terminal 6 does not have a function to acquire location information, the location information of terminal 6 may be acquired by another sensing device and transmitted to the base station 2.

[0017] The base station 2 also obtains charging information from the relay device 8 under its control and transmits it to the information processing unit 4. The charging information is information related to the charging unit 88. The charging unit 88 is, for example, a battery. The information related to the charging unit 88 is, for example, the remaining charge or charge amount of the charging unit 88. If the relay device 8 has a power generation unit 89, which will be described later, the information related to the charging unit 88 may also include the amount of power generated by the power generation unit 89.

[0018] The relay device 8 is a reflector capable of dynamic beam control and can relay signals transmitted from the transmitter. By performing beam control based on the location and quality information of the destination terminal 6, the relay device 8 can form a wireless propagation path that follows the movement of terminal 6, thereby guaranteeing stable communication quality.

[0019] Furthermore, the relay device 8 is capable of on / off control in addition to beam control. That is, the relay device 8 can turn off its own power when beam control is not required. Each part of the relay device 8 operates by receiving power from the charging unit 88. The charging unit 88 is, for example, a battery. The battery is assumed to be replaceable.

[0020] The information processing unit 4 determines, based on the received information, whether relaying is necessary when transmitting a signal. If it determines that relaying is necessary, it performs relay control by sending a control signal to the appropriate relay device 8 from among the multiple relay devices 8. Relay control is performed by determining which relay device 8 to use for establishing communication with the terminal 6 and by determining beam control. Details of relay control will be described later.

[0021] Based on the control signals received from the base station 2, the relay device 8 performs power on / off operations and optimizes relay resources for beam control. Relay resources include, for example, beam intensity, amplification factor, and the number of elements used. In other words, the relay device 8 forms the beam based on the control signals.

[0022] Figure 2 is a block diagram showing the configuration of the wireless communication system according to this disclosure. Referring to Figure 2, the processes commonly performed by the wireless communication system according to this disclosure will be described in more detail. The wireless communication system according to this disclosure comprises a plurality of relay devices 8 and terminals 6. Each of the plurality of relay devices 8 and terminals 6 has the same function.

[0023] Although the wireless communication system of this disclosure is shown here in an embodiment that includes multiple terminals 6, it is not limited to this embodiment, and may also include an embodiment that includes only one terminal 6.

[0024] First, let's explain the path by which base station 2 acquires location information from terminal 6. Terminal positioning unit 62 acquires location information from terminal 6 and transmits it to positioning signal generation unit 64. Positioning signal generation unit 64 transmits the acquired information to information acquisition unit 24. Information acquisition unit 24 transmits the acquired location information to data acquisition unit 42.

[0025] The data acquisition unit 42 transmits the information acquired from the terminal 6 to the database unit 44. The database unit 44 stores the acquired location information.

[0026] Next, the path by which the base station 2 acquires quality information from the terminal 6 will be described. The signal generation unit 66 generates a signal based on the quality information acquired by the terminal 6 and transmits it to the signal transmission / reception unit 68. The signal transmission / reception unit 68 transmits the received signal to the signal transmission / reception unit 25. This transmission is performed via the reflection unit 86 or directly.

[0027] The signal transmission / reception unit 25 transmits the signal acquired from the terminal 6 to the quality acquisition unit 26. The quality acquisition unit 26 acquires quality information based on the signal and transmits it to the data acquisition unit 42.

[0028] The data acquisition unit 42 transmits the acquired information to the database unit 44. The database unit 44 stores the acquired quality information.

[0029] Next, the path by which the base station 2 acquires charging information from the relay device 8 will be explained. The relay device 8 transmits the charging information of the charging unit 88 to the information acquisition unit 24. The information acquisition unit 24 transmits the acquired charging information to the data acquisition unit 42.

[0030] The data acquisition unit 42 transmits the acquired information to the database unit 44. The database unit 44 stores the acquired charging information.

[0031] Next, the path by which base station 2 acquires area information will be explained. Based on the location information, quality information, and charging information stored in the database unit 44, the data processing unit 46 creates area information by linking the area where wireless communication is performed with the relay device 8. When updating area information during the second and subsequent area information creation, the data processing unit 46 acquires the location information, quality information, charging information, and previously created area information stored in the database unit 44, and creates new area information based on that information. The data processing unit 46 then transmits the created area information to the database unit 44.

[0032] The database unit 44 stores the received area information. The control unit 21 of the base station 2 can obtain the area information by accessing the database unit 44.

[0033] Next, we will explain the route for which base station 2 performs relay control based on area information. Based on the area information, control unit 21 determines whether relay is necessary when transmitting a signal.

[0034] If the control unit 21 determines that relaying is necessary, it assigns the appropriate relay device 8 to the area with the worst communication quality, starting with the area with the worst communication quality. This assignment is based on charging information. The control unit 21 then calculates the information necessary for relay control and transmits it 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.

[0035] 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 can be wired or wireless, or any other type.

[0036] The control signal communication unit 82 transmits the received control signal to the wait setting unit 84. The wait setting unit 84 sets parameters to optimize relay resources based on the received control signal. The wait setting unit 84 then transmits the set parameters to the reflection unit 86. The reflection unit 86 optimizes resources based on the received parameters to form an appropriate radio propagation path between the base station 2 and the corresponding terminal 6.

[0037] As described above, the base station 2 can control and manage the relay device 8 from a remote location by transmitting control signals via the control signal communication unit 82.

[0038] Figure 3 is a block diagram showing the configuration of a wireless communication system according to Embodiment 1 of the present disclosure. In the wireless communication system 100, each base station 2 has an information processing unit 4. That is, there are as many information processing units 4 as there are base stations 2.

[0039] Furthermore, the information processing unit 4 includes the control unit 21. The processing performed by the information processing unit 4 in this case will now be explained.

[0040] First, the charging unit 88 transmits charging information, including the remaining charge, to the information acquisition unit 24. The line for transmitting the charging information can be wired or wireless, or any other type. The charging information is assumed to be of an intermittent operation type that is transmitted periodically, but is not limited to this.

[0041] The data processing unit 46 creates area information. Specifically, the data processing unit 46 links the area where wireless communication is performed with the relay device 8 based on positioning information, quality information, and charging information. This linking is performed based on the location information or coverage area of ​​the relay device 8.

[0042] The control unit 21 determines whether relay is necessary when transmitting a signal based on the area information. When the control unit 21 determines that relay is necessary, it assigns an appropriate relay device 8 in order from the area with the worst communication quality. This assignment is performed based on the charging information. For example, the control unit 21 selects a relay device 8 with a large remaining battery level of the charging unit 88 included in the charging information as the relay device 8 to be used for relay. When a plurality of relay devices 8 are linked to the same area, only one of the relay devices 8 is selected.

[0043] The relay device 8 assigned by the control unit 21 optimizes the relay resources after turning on its own power based on the received control signal. The relay device 8 not assigned by the control unit 21 turns off its own power based on the received control signal.

[0044] As described above, when the information processing unit 4 is housed in the base station 2, the base station 2 can perform local control only by the relay devices 8 and terminals 6 under its jurisdiction. That is, the base station 2 can easily perform individual control such as setting a threshold value for each base station.

[0045] FIG. 4 is a diagram showing an image of transmitting a control signal according to Embodiment 1 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 associating parameters for optimizing relay resources with parameters 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.

[0046] For example, the control signal communication unit 23 broadcasts the control signal transmitted from the control unit 21. The broadcast control signal has area information to be controlled. When the area information included in the control signal is an area associated with itself, the plurality of relay devices 8 optimize the relay resources using the parameters included in the control signal. When the received control signal has an ID linked to itself, the plurality of relay devices 8 optimize the relay resources using the parameters linked to the ID.

[0047] FIG. 5 is a diagram showing an example of the hardware configuration of the base station according to Embodiment 1 of the present disclosure. Each function of the base station 2 may be partially or entirely configured by hardware such as a PLD (Programmable Logic Device) or an FPGA (Field Programmable Gate Array), or may be configured as a program executed by a processor such as a CPU.

[0048] 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 through a network.

[0049] As shown in FIG. 5, the base station 2 includes 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 has functions as a computer. Further, the base station 2 is capable of inputting and outputting data to and from a computer-readable storage medium 207.

[0050] The input unit 200 is, for example, a keyboard and a mouse. The output unit 201 is, for example, a display device such as a display.

[0051] The communication unit 202 is, for example, a communication interface for communicating with a wireless device to be controlled.

[0052] The CPU 203 controls each part constituting the base station 2 and performs predetermined processing and the like. The memory 204 and the HDD 205 store data and the like.

[0053] The storage medium 207 is capable of storing a program for executing the functions of the base station 2. Note that the architecture of the base station 2 is not limited to the example shown in FIG. 5.

[0054] Figure 6 is a flowchart illustrating relay control according to Embodiment 1 of the present disclosure. First, in step 100, the base station 2 obtains the communication quality Pr at the destination terminal 6. Specifically, the information processing unit 4 extracts a specific communication quality Pr at the destination terminal 6 from the quality information. Communication quality Pr is information related to communication quality, such as RSSI.

[0055] Next, in step 102, base station 2 determines whether the communication quality Pr is greater than the threshold Pth. If the communication quality Pr is greater than the threshold Pth, the process proceeds to step 104. If the communication quality Pr is less than or equal to the threshold Pth, the process proceeds to step 106.

[0056] The threshold Pth is a standard quality indicator used to determine whether relaying is necessary, and is, for example, a specific value of RSSI. The threshold Pth may be a value set as needed depending on the situation, or it may be a pre-set intrinsic value. A pre-set intrinsic value is, for example, a value registered by default at the time of factory shipment.

[0057] In step 104, the base station 2 decides to turn off the power to all of the relay devices 8 that it controls, and proceeds to step 118.

[0058] In step 106, the base station 2 extracts the available relay devices 8 and obtains their number k and the remaining power of the relay devices 8.

[0059] An assignable relay device 8 is a relay device that can improve the communication quality at terminal 6 by beamforming. An assignable relay device 8 is, for example, a relay device 8 that can make the communication quality Pr of the terminal 6 greater than the threshold Pth. An assignable relay device 8 may be obtained, for example, by extracting an appropriate relay device 8 based on the positional relationship between the base station 2 and terminal 6.

[0060] Alternatively, the assignable relay devices 8 may be obtained by selecting relay devices 8 that can keep the total power consumption of the wireless communication system 100 below a specific threshold or below a certain percentage. The total power consumption is the sum of the amounts of power required to operate the wireless communication system 100. The power required to operate the wireless communication system 100 includes, for example, the transmission power of the base station 2, the power required to control the base station 2, and the operating power of the relay devices 8.

[0061] For example, when a base station 2 and a terminal 6 establish communication in a shielded environment, the base station 2 needs to increase its transmission power. On the other hand, if an appropriate relay device 8 is used in the same shielded environment, shielding can be avoided through relay control, eliminating the need to increase the transmission power of the base station 2. Therefore, by selecting a relay device 8 whose operating power is lower than the transmission power of the base station 2 required to avoid shielding, the total power consumption of the wireless communication system 100 can be kept below a specific threshold or a certain percentage.

[0062] Alternatively, assignable relay devices 8 may be obtained by extracting relay devices 8 in which the base station 2 and terminal 6 are located in a relayable area by beam control. Or, assignable relay devices 8 may be obtained by extracting relay devices 8 whose remaining power is above a predetermined threshold. This threshold may be set in stages, and the threshold and up to which stage of the threshold to extract may be set arbitrarily.

[0063] Next, in step 108, base station 2 determines whether the number k of available relay devices 8 is 0. If it is 0, proceed to step 104. If it is not 0, proceed to step 110.

[0064] In step 110, the base station 2 determines whether the number k of assignable relay devices 8 is 2 or greater. If it is 2 or greater, proceed to step 112. If it is less than 2, proceed to step 116.

[0065] In step 112, base station 2 selects a relay device 8 to assign from among the available relay devices 8. This selection is made based on the remaining battery power obtained in step 106. For example, base station 2 selects and assigns the relay device 8 with the largest remaining battery power from among the available relay devices 8. At this time, base station 2 decides to turn on the power to the assigned relay device 8.

[0066] Next, in step 114, base station 2 decides to turn off the power to the relay device 8 that was not selected, and proceeds to step 118.

[0067] In step 116, base station 2 selects a relay device 8 to assign from among the available relay devices 8, and proceeds to step 118. In this case, since the number k of available relay devices 8 is 1, that relay device 8 is selected.

[0068] In step 118, the base station 2 controls the corresponding relay device 8 and completes the process. For example, the base station 2 broadcasts a control signal that includes on / off information for each relay device 8 to be controlled. Alternatively, the base station 2 may transmit a control signal that includes a signal to instruct the selected relay device 8 to power on, and a control signal that instructs the unselected relay device 8 to power off. As a result, the base station 2 can cause the selected relay device 8 to form a beam based on the control signal.

[0069] Furthermore, the control to turn off the power of the relay device 8 may be implemented by doing nothing if it is known that the power of the relay device 8 in question is already turned off. Also, the state in which the power of the relay device 8 is turned off may include a so-called standby state in which the power of the relay device 8 is on but beamforming is not being performed.

[0070] As described above, in the relay control according to this embodiment, when multiple relay devices 8 are linked to the same area, the relay device 8 with the largest remaining charge in the charging unit 88 is selected. As a result, the bias in the relay devices 8 used can be eliminated, and the operating time of all relay devices 8 can be extended.

[0071] For example, the wireless communication system 100 according to this embodiment can determine that relaying is not necessary during times when there are no users with terminals 6, and therefore can turn off all relay devices 8. Furthermore, even when the wireless communication system 100 according to this embodiment determines that relaying is necessary during times when there are users with terminals 6, it can select a relay device 8 with a large remaining charge in the charging unit 88. In this way, the operating time of the relay devices 8 can be extended regardless of whether there are users or not.

[0072] Furthermore, the relay devices 8 that were not selected at this time can be used to improve the communication quality in other areas. In this way, by controlling multiple relay devices 8 for each of the multiple areas controlled by the base station 2, the secondary effect of improving the overall wireless communication quality of the entire area can be obtained.

[0073] The relay control described above is performed periodically. The area information used in the first relay control is created based on the quality information when the relay device 8 is powered off. For subsequent relay control, the area information created again with the relay device 8 powered off is used, so a process to turn off the relay device 8 power beforehand may be added.

[0074] Alternatively, if the relay device 8 was powered on in the previous process, instead of using area information created again with the relay device 8 powered on, the threshold used in step 102 may be changed. For example, a new threshold Pth' may be set, which includes a safety margin added to the threshold Pth, and step 102 may be changed to a process that determines whether the communication quality P is greater than the threshold Pth'.

[0075] By adding the above-described process, the power to the relay device 8 can be turned off when the standard quality at terminal 6 is met due to changes in location information or communication quality over time, even without using the relay device 8. In other words, it is possible to prevent power from being consumed more than necessary.

[0076] Hereafter, examples of strategies applicable to the relay control according to this embodiment will be shown. This relay control may be carried out with a strategy of optimizing the threshold Pth in order to maximize the communication quality Pr. For example, the threshold Pth may be optimized to maximize the communication quality Pr by simulating the communication quality Pr when the threshold Pth is dynamically changed.

[0077] Furthermore, if the communication quality Pr does not improve during the relay control performed periodically after selecting and assigning one relay device 8 with the largest remaining power in step 112, all relay devices 8 may be turned off and the relay control may be re-executed.

[0078] Alternatively, this relay control may be implemented by optimizing the output of the transmitted power or the threshold Pth according to the balance between transmitted power and received power in wireless communication. Furthermore, this relay control may be implemented by optimizing the frequency of use between the cooperating relay devices 8.

[0079] Figure 7 shows a wireless communication system according to a comparative example. The wireless communication system 500 according to the comparative example comprises a base station 2, a terminal 6, and relay devices 8a, 8b, and 8c.

[0080] The relay device 8 comprises a relay unit, a control controller, and a charging unit 88. The charging unit 88 is, for example, a battery or an external power supply. The relay device 8 controls the relay unit or the control controller, assuming power is supplied from the charging unit 88.

[0081] In the wireless communication system 500, when selecting the relay method, one relay device is selected from among relay devices 8a, 8b, and 8c. Depending on the selection of the relay method, there may be a bias in the relay devices used. In that case, there will also be a bias in the power consumption of each relay device, and therefore a bias in the battery level of each relay device. As a result, there was a problem that some relay devices would run out of battery power, resulting in periods or times when they could not be used.

[0082] In this embodiment, when multiple relay devices 8 are linked to the same area, the wireless communication system 100 selects the relay device 8 with the most remaining charge in its charging unit 88. As a result, the bias in the relay devices 8 used can be eliminated, and the operating time of all relay devices 8 can be extended.

[0083] Embodiment 2 Figure 8 is a flowchart illustrating the relay control according to Embodiment 2 of the present disclosure. The relay control according to Embodiment 2 differs from that of Embodiment 1 in that it targets multiple terminals 6.

[0084] First, in step 120, the base station 2 obtains the remaining power of each relay device 8. This is done in a later step to select which relay device 8 to allocate based on the remaining power.

[0085] Next, in step 122, the base station 2 obtains the communication quality Pr at all destination terminals 6.

[0086] Next, in step 124, base station 2 determines whether all communication quality Pr is greater than the threshold Pth. If all communication quality Pr is greater than the threshold Pth, proceed to step 126. If there are any communication quality Pr that are less than or equal to the threshold Pth, proceed to step 128.

[0087] In step 126, the base station 2 decides to turn off the power to all of the relay devices 8 that it controls, and proceeds to step 136.

[0088] In step 128, base station 2 selects terminal 6. This selection is performed, for example, by selecting all terminal 6 whose communication quality Pr is less than or equal to the threshold Pth.

[0089] Next, in step 130, base station 2 selects a relay device 8 to assign from among the available relay devices 8. This selection is made based on the remaining battery level obtained in step 120. For example, base station 2 selects and assigns the relay device 8 with the largest remaining battery level from among the available relay devices 8. At this time, base station 2 decides to turn on the power to the assigned relay device 8.

[0090] Next, in step 132, the base station 2 determines whether the allocation of the relay device 8 is complete. If it is complete, the process proceeds to step 134. If it is not complete, the process proceeds to step 128 and is repeated.

[0091] Note that the state in which the allocation of relay devices 8 is completed means that relay devices 8 have been allocated to all terminals 6 whose communication quality Pr is below the threshold Pth, or that all available relay devices 8 have been allocated to terminals 6 whose communication quality Pr is below the threshold Pth. In other words, the process in steps 128 to 132 is the process of allocating available relay devices 8 to all terminals 6 whose communication quality Pr is below the threshold Pth, in order from worst to best communication quality Pr.

[0092] In step 134, base station 2 decides to turn off the power to the relay device 8 that was not selected, and proceeds to step 136.

[0093] In step 136, base station 2 controls the corresponding relay device 8 and completes the process. For example, base station 2 broadcasts a control signal that includes on / off information for each relay device 8 to be controlled. Alternatively, base station 2 may transmit a control signal that includes a signal to power on the selected relay device 8, and a control signal that instructs the unselected relay device 8 to power off. As a result, base station 2 can cause the selected relay device 8 to form a beam based on the control signal.

[0094] As described above, the relay control according to this embodiment can eliminate any bias in the relay devices 8 used, even when targeting multiple terminals 6. As a result, the operating time of all relay devices 8 can be extended.

[0095] Embodiment 3 Figure 9 is a diagram showing an image of the transmission of a control signal according to Embodiment 3 of the present disclosure. The wireless communication system 100a according to this embodiment differs from the wireless communication system 100 in that it includes a relay device 8a having an external sensor 87.

[0096] The relay device 8a has an external sensor 87. The external sensor 87 acquires the remaining charge of the charging unit 88 and transmits charging information, including the remaining charge, to the information acquisition unit 24. The line for transmitting the charging information can be wired or wireless, or any other method. In other words, the base station 2 can acquire charging information, including the remaining charge, by receiving a signal from the external sensor 87.

[0097] The acquisition of the remaining charge of the charging unit 88 by the external sensor 87 may, for example, involve taking an image of the remaining charge of the charging unit 88 with the camera if the external sensor 87 is a camera. In this case, the charging unit 88 shall have a function that allows the remaining charge to be visualized. Alternatively, the acquisition of the remaining charge of the charging unit 88 by the external sensor 87 may, for example, involve measuring the remaining charge of the charging unit 88 with an external tester if the external sensor 87 is an external tester.

[0098] As described above, in the relay control according to this embodiment, the remaining charge of the charging unit 88 is acquired by the external sensor 87. As a result, the charging unit 88 does not need to have a function to transmit the remaining charge itself, and thus the charging unit 88 can be simplified.

[0099] Embodiment 4 Figure 10 shows an image of the transmission of a control signal according to Embodiment 4 of the present disclosure. The wireless communication system 100b according to this embodiment differs from the wireless communication system 100 in that it includes a relay device 8b having a power generation unit 89.

[0100] The relay device 8b has a power generation unit 89. The power generation unit 89 supplies the generated power to the charging unit 88. Power generation is assumed to be from environmental energy harvesting, but is not limited to this. Environmental energy harvesting is, for example, solar power generation.

[0101] The charging unit 88 is charged by power supplied from the power generation unit 89. The charging unit 88 also transmits charging information, including the remaining charge, to the information acquisition unit 24. The line for transmitting the charging information can be wired or wireless, or any other method. The charging information is assumed to be of an intermittent operation type that is transmitted periodically, but is not limited to this.

[0102] The charging described above may be performed only when the power to the relay device 8 is off, or it may be performed continuously. In other words, the power generation unit 89 may charge the relay device 8 only when the power to the relay device 8 is off, or it may charge it continuously.

[0103] The relay device 8 may also operate by receiving power from the power generation unit 89. In this configuration, the charging unit 88 functions as a buffer to avoid momentary power outages, etc. Also in this configuration, when the power supply to the relay device 8 is off, there is no need to use the power supplied from the power generation unit 89 to operate the relay device 8. Therefore, the power generation unit 89 can charge the relay device 8 when the power supply to the relay device 8 is off.

[0104] As described above, in the relay control according to this embodiment, the charging unit 88 is charged by the power supplied from the power generation unit 89. Therefore, the charging unit 88 can be charged by turning off the power to the relay device 8 that was not selected in the relay control. As a result, the remaining charge of the corresponding relay device 8 can be restored, and the operating time of all relay devices 8 can be further extended.

[0105] Embodiment 5 Figure 11 is a diagram showing an image of the transmission of a control signal according to Embodiment 5 of the present disclosure. The wireless communication system 100c according to this embodiment differs from the wireless communication system 100b in that the power generation unit 89 transmits the amount of power generated to the base station 2.

[0106] The relay device 8c has a power generation unit 89. The power generation unit 89 transmits the amount of power generated to the information acquisition unit 24. The line for transmitting the amount of power generated can be wired or wireless, or any other type.

[0107] When selecting a relay device 8 to assign from among the available relay devices 8, base station 2 may make the selection based on power generation in addition to remaining power. For example, base station 2 selects and assigns one relay device 8 with the largest remaining power from among the available relay devices 8. In this case, if there are multiple relay devices 8 with the largest remaining power, base station 2 may prioritize selecting a relay device 8 with the largest power generation.

[0108] As described above, in the relay control according to this embodiment, the power generation unit 89 transmits the amount of power generated to the base station 2. When the base station 2 selects a relay device 8 to assign from among the available relay devices 8, it can make the selection based on the amount of power generated in addition to the remaining charge. As a result, it is possible to prioritize the selection of a relay device 8 that recovers quickly during charging, thereby further extending the operating time of all relay devices 8.

[0109] Embodiment 6 Figure 12 is a diagram showing an image of the transmission of a control signal according to Embodiment 6 of the present disclosure. The wireless communication system 100d according to this embodiment differs from the wireless communication system 100 in that it includes a relay device 8d having an external sensor 87 and a power generation unit 89.

[0110] The relay device 8d has an external sensor 87. The external sensor 87 acquires the remaining charge of the charging unit 88 and transmits charging information, including the remaining charge, to the information acquisition unit 24.

[0111] The relay device 8d also has a power generation unit 89. The power generation unit 89 supplies the generated electricity to the charging unit 88.

[0112] The charging unit 88 is charged by the power supplied from the power generation unit 89. The charging unit 88 also transmits charging information, including the remaining charge, to the information acquisition unit 24.

[0113] As described above, in the relay control according to this embodiment, the remaining charge of the charging unit 88 is acquired by the external sensor 87. As a result, the charging unit 88 does not need to have a function to transmit the remaining charge itself, and thus the charging unit 88 can be simplified.

[0114] Furthermore, in the relay control according to this embodiment, the charging unit 88 is charged by the power supplied from the power generation unit 89. Therefore, the charging unit 88 can be charged by turning off the power to the relay device 8 that was not selected in the relay control. As a result, the remaining charge of the corresponding relay device 8 can be restored, and the operating time of all relay devices 8 can be further extended.

[0115] 2 Base station 6 Terminal 8 Relay device 8a Relay device 8b Relay device 8c Relay device 8d Relay device 87 External sensor 89 Power generation unit

Claims

1. A wireless communication device that communicates wirelessly with a terminal and controls a plurality of relay devices used for the wireless communication, the wireless communication device is configured to perform the following steps: extract a relay device that can improve the communication quality at the terminal by beamforming; acquire the remaining power of the extracted relay device; select the relay device with the largest remaining power and cause the selected relay device to beamform; and turn off the power of the relay devices that were not selected from the plurality of relay devices.

2. The wireless communication device according to claim 1, wherein the relay device has an external sensor having a function of acquiring and transmitting the remaining charge, and the process of acquiring the remaining charge includes the process of receiving a signal from the external sensor.

3. The wireless communication device according to claim 1, wherein the relay device has a power generation unit, and the power generation unit charges the relay device when the power supply to the relay device is turned off.

4. A wireless communication method for controlling relay devices capable of relaying wireless communication between a base station and a terminal, comprising: extracting relay devices capable of improving communication quality at the terminal by beamforming; obtaining the remaining power of the extracted relay devices; selecting the relay device with the largest remaining power and causing the selected relay device to beamform; and turning off the power of the relay devices that were not selected among the plurality of relay devices.

Images