Wireless communication device and wireless communication method

Abstract

This wireless communication device comprises: a plurality of wireless communication units that form directional beams in different directions and communicate with a plurality of other wireless communication devices; and a wireless control unit that, on the basis of quality information for wireless communication lines of each of the plurality of wireless communication units, when the wireless communication quality indicated by the quality information becomes less than or equal to a threshold value, controls one or more wireless communication units not marked to be used for communication among the plurality of wireless communication units and disconnects the connection with the other wireless communication device or devices to which said one or more wireless communication units is or are connected.　

Description

Wireless communication device and wireless communication method

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

[0002] Wireless communication using high frequency bands such as millimeter waves can ensure a wider bandwidth than wireless communication using microwaves. IEEE 802.11ad is an example of a wireless communication method using high frequency bands. Wireless communication using high frequency bands has advantages such as high linearity of wireless signals in propagation paths and less interference with other wireless communication. Therefore, studies are underway to popularize wireless communication using high frequency bands (see, for example, Non-Patent Document 1).

[0003] The distance attenuation of a radio signal in a propagation path increases with the frequency of the radio signal. Radio signals in wireless communications using the 60 GHz band, such as IEEE 802.11ad, are easily absorbed by oxygen in the propagation path. For this reason, in wireless communications using high frequency bands such as millimeter waves, a wireless communication device typically forms a directional beam (beamforming) toward a wireless communication device with which it is communicating, and transmits the signal. It is also common for wireless communication devices to form a directional beam and receive the signal (see, for example, Non-Patent Document 2).

[0004] International Publication No. 2022 / 024241

[0005] Takinami et al., "Standardization Trends and Elemental Technologies of Millimeter-Wave Wireless LAN Systems," IEICE Communications Society Magazine, Fall 2016, No. 38, pp. 100-106. IEEE, "Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 3: Enhancements for Very High Throughput in the 60 GHz Band" (IEEE Std 802.11ad-2012), December 28, 2012.

[0006] In wireless communication systems using high frequency bands, communication is performed using directional beams, which poses a problem of rapid degradation of wireless transmission characteristics due to mismatches in the orientation of the antennas of the wireless communication devices communicating and the presence of obstructions on the communication path. Fig. 5 is a diagram showing an example of a wireless communication system in which a base station device 1 installed on the ground communicates with a terminal device 2 installed on a robot cart R. In the situation shown in Fig. 5, the antennas of the base station device 1 and the terminal device 2 are directly facing each other, so wireless communication with high communication quality can be expected.

[0007] On the other hand, as shown in Figure 6, it is assumed that as the robot cart R moves, the antennas of the base station device 1-1 and the terminal device 2 will no longer face each other. For example, under the conditions shown in Figure 6, it is difficult for the antennas of the opposing wireless communication device to be directly visible from the antennas of the base station device 1-1 and the terminal device 2. Under such conditions, if there is a reflecting object W such as a wall shown in Figure 6, communication may be possible through the reflected path shown by the dotted line, but communication is not possible if there is no reflecting object W.

[0008] Furthermore, depending on the material of the reflector W, radio waves may be absorbed, resulting in a deterioration in communication quality compared to when the antenna is directly facing the object. Thus, in high frequency bands, the combination of antenna orientations of wireless communication devices can significantly degrade communication characteristics, resulting in unstable communication.

[0009] In a situation where multiple base station devices are installed, it is possible that another base station device 1-2 may be present in the direction of the antenna of the terminal device 2 as the robot cart R moves, as shown in FIG. 6 , or that another base station device 1-3 may be present near the base station device 1-1 to which the terminal device 2 was initially connected, as shown in FIG. 7 . However, when a typical terminal device 2 is connected to a specific base station device (e.g., base station device 1-1), it uses its wireless communication unit to communicate with that specific base station device. As a result, it is unable to detect whether there are other base station devices 1-2 or 1-3 with better quality, or even if it can, it only does so periodically, and is therefore unable to discover other base station devices 1-2 or 1-3 in real time. Therefore, conventional wireless communication systems using high-frequency bands are unable to immediately respond to degradation in wireless communication quality that occurs when the antennas of the communicating wireless communication devices are not directly facing each other (e.g., when the wireless communication devices rotate).

[0010] 8, by providing the terminal device 2 with multiple wireless communication units, it is possible to provide redundancy for the wireless communication links, and when the quality of one wireless communication link deteriorates, it is possible to cope with a deterioration in wireless communication quality by performing communication using the remaining wireless communication link. Furthermore, as shown in Patent Document 1, it is possible to improve the stability of wireless communication by controlling so that multiple wireless communication units are not connected to the same base station device.

[0011] However, even if the terminal device 2 is equipped with multiple wireless communication units, if the wireless communication quality of both of the multiple wireless communication units simultaneously deteriorates due to, for example, the robot cart R rotating as shown in Fig. 8, the effect of redundancy may not be obtained. As described above, in the terminal device 2 in which wireless communication link redundancy is intended, if the terminal device 2 does not appropriately connect to a base station device with good quality (even if control is performed to prevent connection to the same base station device in this case), the effect of wireless communication link redundancy cannot be obtained, and as a result, the quality of the wireless communication link deteriorates.

[0012] In view of the above circumstances, an object of the present invention is to provide a technique that can suppress degradation in the quality of a wireless communication link when a wireless communication device is equipped with a plurality of wireless communication units.

[0013] One aspect of the present invention is a wireless communication device comprising: a plurality of wireless communication units that form directional beams in different directions to communicate with a plurality of other wireless communication devices; and a wireless control unit that, based on quality information of the wireless communication lines of each of the plurality of wireless communication units, controls one or more wireless communication units among the plurality of wireless communication units that are not marked for use in communication when the wireless communication quality indicated by the quality information falls below a threshold, thereby disconnecting the connection between the one or more wireless communication units and the other wireless communication devices to which they are connected.

[0014] One aspect of the present invention is a wireless communication method in which, based on quality information of the wireless communication lines of multiple wireless communication units that form directional beams in different directions and communicate with multiple other wireless communication devices, when the wireless communication quality indicated by the quality information falls below a threshold, one or more wireless communication units among the multiple wireless communication units that are not marked for use in communication are controlled to disconnect the connection with the other wireless communication devices to which the one or more wireless communication units are connected.

[0015] According to the present invention, it is possible to suppress degradation in the quality of a wireless communication link when a wireless communication device is equipped with a plurality of wireless communication units.

[0016] 1 is a diagram illustrating an example of the configuration of a wireless communication device in a first embodiment. FIG. 2 is a flowchart illustrating the processing flow of a wireless communication device in a first embodiment. FIG. 3 is a flowchart illustrating the processing flow of a wireless communication device in a third embodiment. FIG. 4 is a flowchart illustrating the processing flow of a wireless communication device in a fourth embodiment. FIG. 5 is a diagram illustrating an example of a wireless communication system in which a base station device installed on the ground and a terminal device installed on a robot cart communicate with each other. FIG. 6 is a diagram illustrating an example of a wireless communication system in which a base station device installed on the ground and a terminal device installed on a robot cart communicate with each other. FIG. 7 is a diagram illustrating an example of a wireless communication system in which a base station device installed on the ground and a terminal device installed on a robot cart communicate with each other. FIG. 8 is a diagram illustrating an example of a wireless communication system in which a base station device installed on the ground and a terminal device installed on a robot cart communicate with each other.

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] (First embodiment) Fig. 1 is a diagram showing an example of the configuration of a wireless communication device 10 in a first embodiment. The wireless communication device 10 includes multiple wireless communication units and performs wireless communication with multiple other wireless communication devices. Here, as an example, the wireless communication device 10 is described as a terminal station device, and the multiple other wireless communication devices are base station devices. Note that the wireless communication device 10 may be a base station device, and the multiple other wireless communication devices may be terminal station devices.

[0019] The wireless communication device 10 includes a data processing unit 11, multiple wireless communication units 12-1 and 12-2, a quality information collecting unit 13, a wireless control unit 14, and multiple antennas 15-1 and 15-2. Note that while Fig. 1 shows a configuration in which the wireless communication device 10 includes two wireless communication units 12 and antennas 15, the wireless communication device 10 may be configured to include three or more wireless communication units 12 and antennas 15.

[0020] The data processing unit 11 inputs and outputs data to and from a higher-level device or another base station that is located above the wireless communication device 10. For example, the data processing unit 11 transmits a signal received from another wireless communication device to the higher-level device or another base station. For example, the data processing unit 11 receives a signal addressed to another wireless communication device from the higher-level device or another base station.

[0021] The wireless communication unit 12 controls the amplitude or phase of the antenna 15 in accordance with instructions from the wireless control unit 14 to form directional beams in different directions. Note that there is no particular limit to the number of directional beams formed by the wireless communication device 10. A directional beam is a beam that has directivity in a specific direction. The wireless communication unit 12 switches the directional beams and transmits signals in accordance with instructions from the wireless control unit 14. The wireless communication unit 12 receives signals (e.g., responses) transmitted from the wireless communication device 20 via the antenna 15.

[0022] The quality information collecting unit 13 collects quality information of wireless communication links connected to each wireless communication unit 12. The quality information is information related to wireless communication quality, and may be, for example, a received signal strength indication (RSSI) of a reference signal transmitted from another wireless communication device obtained when the wireless communication device 10 selects a directional beam, a signal-to-noise ratio (SNR) obtained by estimating received signal power and noise, information for identifying which directional beam was actually used in communication, such as the ID of the directional beam, or information on transmission distance obtained by a distance estimation function (e.g., estimation of transmission distance based on RTT: Round-Trip Time), or a combination thereof.

[0023] The wireless control unit 14 controls each wireless communication unit 12. For example, the wireless control unit 14 selects a wireless communication unit 12 to use for communication from among the plurality of wireless communication units 12 based on the quality information of each wireless communication unit 12 collected by the quality information collection unit 13. For example, the wireless control unit 14 selects, from among the plurality of wireless communication units 12, the wireless communication unit 12 having the best wireless communication quality indicated by the quality information as the wireless communication unit 12 to use for communication.

[0024] Furthermore, when it is determined that the wireless communication quality indicated by the quality information of a wireless communication unit 12 other than the selected wireless communication unit 12 is equal to or lower than a threshold, the wireless communication control unit 14 disconnects the wireless communication link of the wireless communication unit 12 whose wireless communication quality is equal to or lower than the threshold. That is, when it is determined that the wireless communication quality is equal to or lower than the threshold, the wireless control unit 14 controls the wireless communication unit 12 whose wireless communication quality is equal to or lower than the threshold to disconnect the currently connected connection with another wireless communication device.

[0025] The antenna 15 forms directional beams in different directions under the control of the wireless communication unit 12. The antenna 15 transmits signals by emitting radio waves using the formed directional beams. The antenna 15 receives radio waves transmitted from other wireless communication devices using the formed directional beams.

[0026] 2 is a flowchart showing the flow of processing in the wireless communication device 10 according to the first embodiment. In the explanation of FIG. 2, the other wireless communication devices to which the wireless communication units 12-1 and 12-2 of the wireless communication device 10 connect are assumed to be wireless communication devices 20-1 and 20-2.

[0027] The wireless control unit 14 acquires quality information of the wireless communication links of the wireless communication units 12-1 and 12-2 (step S101). For example, the wireless control unit 14 acquires quality information of the wireless communication link between the wireless communication unit 12-1 and the wireless communication device 20-1, and acquires quality information of the wireless communication link between the wireless communication unit 12-2 and the other wireless communication device 20-2.

[0028] The wireless control unit 14 determines whether acquisition of quality information has been completed for each wireless communication unit 12 (step S102). For example, the wireless control unit 14 determines that acquisition of quality information has been completed when quality information has been acquired for all wireless communication units 12 connected to different wireless communication devices 20. For example, the wireless control unit 14 determines that acquisition of quality information has not been completed when quality information has not been acquired for all wireless communication units 12 connected to different wireless communication devices 20.

[0029] If the wireless control unit 14 determines that acquisition of quality information has not been completed for each wireless communication unit 12 (step S102—NO), the process returns to step S101. If the wireless control unit 14 determines that acquisition of quality information has been completed for each wireless communication unit 12 (step S102—YES), the wireless control unit 14 identifies the wireless communication unit 12 communicating via the wireless communication link with the highest quality based on the acquired quality information.

[0030] The wireless control unit 14 marks the identified wireless communication unit 12 (e.g., wireless communication unit 12-1) for use in communication (step S103). Thereafter, the wireless control unit 14 determines whether the number N (N is an integer equal to or greater than 0) of wireless communication units 12 connected to each wireless communication device 20 is greater than 1 (step S104). If the wireless control unit 14 determines that the number N of wireless communication units 12 connected to each wireless communication device 20 is less than 1 (step S105—NO), the process returns to step S101.

[0031] On the other hand, if the wireless control unit 14 determines that the number N of wireless communication units 12 connected to each wireless communication device 20 is greater than 1 (step S105—YES), the wireless communication device 10 initializes the constant i (step S105). Thereafter, the wireless control unit 14 adds "1" to the constant i to set a new constant i (step S106). Next, the wireless control unit 14 determines whether the i-th wireless communication unit 12-i connected to the wireless communication device 20 is marked for use in communication (step S107). If i=1, the wireless control unit 14 determines whether the first wireless communication unit 12-1 connected to the wireless communication device 20 (e.g., wireless communication device 20-1) is marked for use in communication.

[0032] If the wireless control unit 14 determines that the i-th wireless communication unit 12-i connected to the wireless communication device 20 is marked for use in communication (step S107—YES), the process returns to step S106. That is, if the wireless control unit 14 determines that the i-th wireless communication unit 12-i connected to the wireless communication device 20 is marked for use in communication, the wireless control unit 14 adds "1" to the constant i to create a new constant i. In this way, the wireless control unit 14 repeatedly executes the process of step S107 until it identifies a wireless communication unit 12 that is connected to the wireless communication device 20 and is not marked for use in communication.

[0033] If the wireless control unit 14 determines that the i-th wireless communication unit 12-i connected to the wireless communication device 20 is not marked for use in communication (step S107—NO), the wireless control unit 14 determines whether the wireless communication quality indicated by the quality information of the i-th wireless communication unit 12-i connected to the wireless communication device 20 is equal to or lower than a threshold (step S108). Here, the threshold is desirably set to a value that can be considered to indicate poor quality of the wireless communication link. When i=1, the wireless control unit 14 determines whether the wireless communication quality of the first wireless communication unit 12-1 connected to the wireless communication device 20 (e.g., wireless communication device 20-1) is equal to or lower than a threshold.

[0034] If the wireless control unit 14 determines that the wireless communication quality of the i-th wireless communication unit 12-i connected to the wireless communication device 20 is not equal to or less than the threshold (step S108-NO), the process returns to step S106. That is, if the wireless control unit 14 determines that the wireless communication quality of the i-th wireless communication unit 12-i connected to the wireless communication device 20 is greater than the threshold, the wireless control unit 14 adds "1" to the constant i to set a new constant i. In this way, the wireless control unit 14 repeatedly executes the process of step S108 until it identifies a wireless communication unit 12 that is connected to the wireless communication device 20, is not marked as being used for communication, and has wireless communication quality equal to or less than the threshold.

[0035] If the wireless control unit 14 determines that the wireless communication quality of the ith wireless communication unit 12-i connected to the wireless communication device 20 is equal to or lower than the threshold (step S108-YES), the wireless control unit 14 controls the ith wireless communication unit 12-i connected to the wireless communication device 20 to disconnect the connection with the wireless communication device 20 with which it is currently communicating. For example, if the ith wireless communication unit 12-i connected to the wireless communication device 20 is the wireless communication unit 12-2, the wireless control unit 14 controls the wireless communication unit 12-2 to disconnect the connection with the wireless communication device 20 with which it is currently communicating (for example, the wireless communication device 20-2) (step S109).

[0036] In this way, the wireless control unit 14 checks whether each wireless communication unit 12 connected to the wireless communication device 20 is marked for use in communication and whether the wireless communication quality of each wireless communication unit 12 is equal to or lower than the threshold value. If the wireless communication unit 12 is not marked for use in communication and the wireless communication quality of that wireless communication unit 12 is equal to or lower than the threshold value, the wireless control unit 14 instructs the corresponding wireless communication unit 12 to disconnect the wireless communication link with the wireless communication device 20.

[0037] The wireless communication unit 12 that has been instructed to disconnect the wireless communication link with the wireless communication device 20 disconnects the wireless communication link with the wireless communication device 20. As a result, the wireless communication unit 12 that has disconnected the wireless communication link with the wireless communication device 20 becomes able to detect a new wireless communication device 20.

[0038] Thereafter, the wireless control unit 14 determines whether the constant i is equal to the number N of wireless communication units 12 connected to each wireless communication device 20 (step S110). If the wireless control unit 14 determines that the constant i is equal to the number N of wireless communication units 12 connected to each wireless communication device 20 (step S110—YES), the process returns to step S106. Note that if the wireless control unit 14 determines that the constant i is equal to the number N of wireless communication units 12 connected to each wireless communication device 20, the wireless communication device 10 may terminate the process shown in FIG. 2 once and then execute the process of step S101 after a predetermined time has elapsed.

[0039] On the other hand, if the wireless control unit 14 determines that the constant i is not the same as the number N of wireless communication units 12 connected to each wireless communication device 20 (step S110-NO), the process returns to step S106. That is, if the wireless control unit 14 determines that the constant i is not the same as the number N of wireless communication units 12 connected to each wireless communication device 20, it adds "1" to the constant i to create a new constant i. In this way, the wireless control unit 14 determines whether all wireless communication units 12 connected to the wireless communication device 20 are marked as being used for communication. Furthermore, the wireless control unit 14 determines the quality of the wireless communication link based on the wireless communication quality for the wireless communication units 12 that are not marked as being used for communication, among all the wireless communication units 12 connected to the wireless communication device 20.

[0040] In the wireless communication device 10 configured as described above, the wireless control unit 14 collects quality information on the wireless communication links of each wireless communication unit 12 and, based on the collected quality information, disconnects the wireless communication link of a wireless communication unit 12 whose quality has fallen below a threshold. In this manner, when the wireless communication device 10, which includes multiple wireless communication units 12, uses the wireless communication unit 12 with the best quality for communication while determining that the communication quality of the other wireless communication units 12 has fallen below a threshold, the wireless communication link of the wireless communication unit 12 whose quality has fallen below the threshold is disconnected. This allows some wireless communication units to maintain connections with other wireless communication devices while immediately starting an operation to detect other wireless communication devices with better quality. Therefore, new other wireless communication devices can be quickly detected and the quality of the wireless communication links can be maintained. This makes it possible to suppress degradation of the quality of wireless communication links even when the wireless communication device 10 includes multiple wireless communication units 12.

[0041] Second Embodiment In the first embodiment, a configuration was described in which the wireless communication links of wireless communication units not used for communication are disconnected based on quality information of wireless communication units other than the wireless communication unit used for communication (the wireless communication unit marked for use in communication). This is to detect other wireless communication devices in response to a deterioration in the quality of each wireless communication unit and attempt to improve the communication quality. However, disconnecting and connecting these wireless communication links may waste communication resources due to the exchange of control information involved. Therefore, in the second embodiment, a configuration will be described in which the wireless communication links of wireless communication units not used for communication are disconnected based on quality information of the wireless communication unit used for communication. With this configuration, it is possible to disconnect communication of the other wireless communication units only when the communication quality of the wireless communication unit used for communication has deteriorated.

[0042] In the second embodiment, the configuration of the wireless communication device 10 is the same as that of the first embodiment, except for the processing performed by the wireless communication device 10. The following description will focus on the differences.

[0043] The wireless control unit 14 controls each wireless communication unit 12. For example, the wireless control unit 14 selects a wireless communication unit 12 to be used for communication from among the multiple wireless communication units 12 based on the quality information of each wireless communication unit 12 collected by the quality information collecting unit 13. Furthermore, when the wireless control unit 14 determines that the wireless communication quality of the selected wireless communication unit 12 is equal to or lower than a threshold, it disconnects the wireless communication links of the wireless communication units 12 other than the selected wireless communication unit 12. Note that the wireless communication units 12 whose wireless communication links the wireless control unit 14 disconnects may be all wireless communication units 12 other than the selected wireless communication unit 12, or may be a preset number of wireless communication units 12.

[0044] When the number of wireless communication units 12 for which the wireless control unit 14 is to disconnect the wireless communication link is a preset number, the wireless control unit 14 may select the candidates for disconnection in descending order of wireless communication quality.

[0045] 3 is a flowchart showing the flow of processing in the wireless communication device 10 in the second embodiment. In the explanation of FIG. 3, the other wireless communication devices to which the wireless communication units 12-1 and 12-2 of the wireless communication device 10 connect will be explained as wireless communication devices 20-1 and 20-2. In FIG. 3, the same processes as those in FIG. 2 are assigned the same reference numerals as those in FIG. 2, and explanations thereof will be omitted.

[0046] When the processes from step S101 to step S103 are completed, the wireless control unit 14 determines whether the wireless communication quality of the wireless communication unit 12 marked to be used for communication in the process of step S103 is equal to or lower than a threshold (step S201). If the wireless control unit 14 determines that the wireless communication quality of the wireless communication unit 12 marked to be used for communication is equal to or lower than the threshold (step S201-YES), the wireless control unit 14 disconnects the wireless communication links of the wireless communication units 12 other than the wireless communication unit 12 marked to be used for communication (step S202).

[0047] The wireless communication units 12 instructed to disconnect the wireless communication link with the wireless communication device 20 (here, the wireless communication units 12 other than the wireless communication units 12 marked for use in communication) disconnect the wireless communication link with the connected wireless communication device 20. This enables the wireless communication units 12 that have disconnected the wireless communication link with the wireless communication device 20 to detect a new wireless communication device 20. Then, the process returns to step S101.

[0048] On the other hand, if the wireless control unit 14 determines that the wireless communication quality of the wireless communication unit 12 marked to be used for communication is not equal to or lower than the threshold (step S201-NO), the process returns to step S101.

[0049] According to the wireless communication device 10 of the second embodiment configured as described above, only when the communication quality of the wireless communication unit used for communication deteriorates, the communication of the wireless communication units other than the wireless communication unit used for communication is disconnected. This makes it possible to immediately start an operation to detect other wireless communication units with better quality while maintaining the connection with the other wireless communication units. Therefore, it is possible to quickly detect new other wireless communication units and maintain the quality of the wireless communication link. Therefore, even when the wireless communication device 10 includes multiple wireless communication units 12, it is possible to suppress deterioration in the quality of the wireless communication link.

[0050] (Third Embodiment) As described in the second embodiment, repeated disconnection and connection of wireless communication links may waste communication resources due to the accompanying exchange of control information. Therefore, in the third embodiment, a configuration will be described in which, when the wireless communication quality of a wireless communication unit marked for use in communication is equal to or higher than a threshold, the communication links of wireless communication units other than the wireless communication unit marked for use in communication are not disconnected. With this configuration, when the communication quality of a wireless communication unit used for communication is equal to or higher than a threshold, the wireless communication links are not disconnected, thereby making it possible to reduce waste of communication resources.

[0051] In the third embodiment, the configuration of the wireless communication device 10 is the same as that of the first embodiment, except for the processing performed by the wireless communication device 10. The following description will focus on the differences.

[0052] The wireless control unit 14 controls each wireless communication unit 12. For example, the wireless control unit 14 selects a wireless communication unit 12 to be used for communication from among the multiple wireless communication units 12 based on the quality information of each wireless communication unit 12 collected by the quality information collection unit 13. Furthermore, when the wireless control unit 14 determines that the wireless communication quality indicated by the quality information of the selected wireless communication unit 12 is below a threshold, it determines whether to disconnect the wireless communication links of the wireless communication units 12 other than the selected wireless communication unit 12.

[0053] When it is determined that the wireless communication quality indicated by the quality information of a wireless communication unit 12 other than the selected wireless communication unit 12 is equal to or lower than a threshold, the wireless communication control unit 14 disconnects the wireless communication link of the wireless communication unit 12 whose wireless communication quality is equal to or lower than the threshold. In other words, when it is determined that the wireless communication quality is equal to or lower than the threshold, the wireless control unit 14 controls the wireless communication unit 12 whose wireless communication quality is equal to or lower than the threshold to disconnect the currently connected connection with another wireless communication device.

[0054] 4 is a flowchart showing the flow of processing in the wireless communication device 10 according to the third embodiment. In the explanation of FIG. 4, the other wireless communication devices to which the wireless communication units 12-1 and 12-2 of the wireless communication device 10 connect will be explained as wireless communication devices 20-1 and 20-2. In FIG. 4, the same processes as those in FIG. 2 are assigned the same reference numerals as those in FIG. 2, and explanations thereof will be omitted.

[0055] When the processes from step S101 to step S103 are completed, the wireless control unit 14 determines whether the wireless communication quality of the wireless communication unit 12 marked as being used for communication in the process of step S103 is equal to or higher than a threshold (step S301). Note that the threshold indicated in step S301 and the threshold indicated in step S108 may be the same value or different values.

[0056] If the wireless control unit 14 determines in the process of step S103 that the wireless communication quality of the wireless communication unit 12 marked to be used for communication is equal to or higher than the threshold (step S301-YES), the process returns to step S101. In this way, if the wireless control unit 14 determines that the wireless communication quality of the wireless communication unit 12 marked to be used for communication is equal to or higher than the threshold, the wireless control unit 14 no longer determines whether to disconnect the wireless communication link.

[0057] On the other hand, if the wireless control unit 14 determines in the processing of step S103 that the wireless communication quality of the wireless communication unit 12 marked to be used for communication is below the threshold (step S301-NO), the processing from step S104 onwards is executed. In this way, if the wireless communication quality of the wireless communication unit 12 marked to be used for communication falls below the threshold (if the wireless communication quality of the wireless communication unit 12 marked to be used for communication deteriorates), the wireless control unit 14 determines whether or not to disconnect the wireless communication link.

[0058] According to the wireless communication device 10 of the third embodiment configured as described above, a determination is made as to whether to disconnect the wireless communication link only when the communication quality of the wireless communication unit used for communication has deteriorated. As a result, if the quality information of the wireless communication unit 12 used for communication is equal to or greater than a threshold, the wireless communication link is not repeatedly disconnected and reconnected. This makes it possible to avoid wasting communication resources. Furthermore, it is possible to immediately start an operation to detect other wireless communication devices with better quality while maintaining a connection with the other wireless communication device. This makes it possible to quickly detect new other wireless communication devices and maintain the quality of the wireless communication link. Therefore, even when the wireless communication device 10 includes multiple wireless communication units 12, it is possible to suppress deterioration in the quality of the wireless communication link.

[0059] (Variation 1 common to the first to third embodiments) In each embodiment, a configuration has been shown in which the wireless communication link of the wireless communication unit 12 marked for use in communication is not disconnected, but the configuration may also be such that the wireless communication link of the wireless communication unit 12 marked for use in communication is disconnected in order to make it easier to detect other wireless communication devices that are expected to have good wireless communication quality.

[0060] (Modification 2 common to the first to third embodiments) Each embodiment can be applied to any wireless communication system. That is, the present invention can be applied to any wireless communication system that uses directional beams, whether it is an autonomous distributed wireless communication system such as IEEE 802.11ad or a centralized control wireless communication system such as 5G (5th Generation) NR (New Radio).

[0061] (Modification 3 common to the first to third embodiments) In each embodiment, the wireless control unit 14 is provided on the terminal device side, and the wireless communication unit 12 is switched based on the wireless control unit 14. However, the wireless control unit 14 may be provided on the base station device side or in an upper network and controlled. Similarly, the present invention also includes a configuration in which the base station device is provided with a plurality of wireless communication units 12 and switches between them.

[0062] (Variant 4 common to the first to third embodiments) The multiple wireless communication units 12 provided in the wireless communication device 10 in each embodiment may conform to the same wireless communication standard, or each may correspond to a different wireless communication standard.

[0063] (Variation 5 common to the first to third embodiments) In each embodiment, the base station device installed on the ground and the terminal device equipped with multiple wireless communication units 12 installed on a robot cart have been described as examples, but the present invention is not limited to application to such a scenario, and can be applied to any wireless communication device such as a wireless communication device equipped with multiple wireless communication units 12 installed on a vehicle, or a smartphone.

[0064] (Variation 6 common to the first to third embodiments) Even if each wireless communication unit 12 disconnects a wireless communication link with another wireless communication device, it may be unable to connect to a new wireless communication device and may reconnect to the original wireless communication device. In this case, since it may be impossible to find another wireless communication device with good quality, the wireless communication unit may be controlled not to connect to the wireless communication device that was connected to the previous wireless communication device for a certain period of time. In each embodiment, the acquisition of quality information and the control of disconnecting the communication link are performed by a loop asynchronous with the communication link connection process. However, the loop may be triggered by the communication link connection process. The quality information may be acquired periodically. That is, a timer may be provided in any of the loops shown in FIGS. 2 to 4 to control the acquisition of quality information at regular intervals. It is expected that quality information will fluctuate over time. Therefore, multiple pieces of quality information may be collected for each wireless communication unit, and the average value may be used as the quality information for the flow.

[0065] Some or all of the functional units of the wireless communication device 10 in the above-described embodiment are realized as software by one or more processors, such as a CPU (Central Processing Unit), executing a program stored in a storage device having a non-volatile storage medium (non-transitory storage medium) and memory. The program may be recorded on a computer-readable non-transitory storage medium. Examples of computer-readable non-transitory storage media include portable media such as flexible disks, magneto-optical disks, ROMs (Read Only Memory), and CD-ROMs (Compact Disc-ROMs), and storage devices such as hard disks built into computer systems.

[0066] Some or all of the functional units of the wireless communication device 10 may be realized using hardware including electronic circuits (electronic circuits or circuitry) using, for example, an LSI (Large Scale Integrated circuit), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0067] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0068] The present invention can be applied to a wireless communication device that performs wireless communication with one or more other wireless communication devices.

[0069] REFERENCE SIGNS LIST 10... wireless communication device, 11... data processing unit, 12, 12-1, 12-2... wireless communication unit, 13... quality information collection unit, 14... wireless control unit, 15, 15-1, 15-2... antenna

Claims

1. A wireless communication device comprising: a plurality of wireless communication units which form directional beams in different directions to communicate with a plurality of other wireless communication devices; and a wireless control unit which, based on quality information of the wireless communication lines of each of the plurality of wireless communication units, controls one or more wireless communication units which are not marked for use in communication when the wireless communication quality indicated by the quality information falls below a threshold, to disconnect the one or more wireless communication units from the other wireless communication devices to which they are connected.

2. The wireless communication device according to claim 1, wherein the wireless control unit compares the wireless communication quality of each of the one or more wireless communication units with the threshold value, and disconnects a connection between a wireless communication unit among the one or more wireless communication units whose wireless communication quality falls below the threshold value and another wireless communication device to which the wireless communication unit is connected.

3. The wireless communication device described in claim 1, wherein the wireless control unit disconnects a connection between at least one of the one or more wireless communication units and another wireless communication device when the wireless communication quality of the wireless communication unit marked for use in the communication falls below a threshold.

4. The wireless communication device described in claim 1 or 2, wherein, when the wireless communication quality of a wireless communication unit marked for use in the communication falls below a threshold and when the wireless communication quality of one or more of the wireless communication units falls below a threshold, the wireless control unit disconnects a connection between the wireless communication unit among the one or more wireless communication units whose wireless communication quality falls below the threshold and another wireless communication device to which the wireless communication unit is connected.

5. A wireless communication device as described in any one of claims 1 to 3, wherein the wireless control unit, after disconnecting the connection with the other wireless communication device, does not reconnect to the disconnected other wireless communication device for a predetermined period of time, but searches for wireless communication devices other than the other wireless communication device.

6. The wireless communication device according to claim 1, wherein the wireless control unit marks the wireless communication unit having the best communication quality among the plurality of wireless communication units as the wireless communication unit to be used for communication.

7. A wireless communication method comprising: based on quality information of wireless communication lines of multiple wireless communication units that form directional beams in different directions and communicate with multiple other wireless communication devices, when the wireless communication quality indicated by the quality information falls below a threshold, controlling one or more wireless communication units among the multiple wireless communication units that are not marked for use in communication, to disconnect the connection between the one or more wireless communication units and the other wireless communication devices to which they are connected.

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