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

Abstract

This wireless communication device comprises: a peripheral environment information collection unit that collects quality information indicating the quality of wireless communication for each combination of each wireless communication device positioned in the periphery and each formable candidate beam; a communication control unit that weights the quality information collected by the peripheral environment information collection unit using a weighting coefficient that makes it easier to select a candidate beam closer to the center among the formable candidate beams, and selects a wireless communication device to communicate with on the basis of the weighted quality information; and a wireless communication unit that wirelessly connects to the selected wireless communication device to communicate with.　

Description

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

[0001] This invention relates to wireless communication devices, wireless communication systems, wireless communication methods, and computer programs.

[0002] Wireless communication using high-frequency bands such as the millimeter wave band allows for wider bandwidth compared to wireless communication using the microwave band. An example of a wireless communication method using high-frequency bands is IEEE 802.11ad. Wireless communication using high-frequency bands has advantages such as high directivity of wireless signals in the propagation path and less interference with other wireless communications. For this reason, research is underway to promote the widespread use of wireless communication using high-frequency bands (see, for example, Non-Patent Document 1).

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

[0004] Figure 18 is a conceptual diagram showing a state in which multiple wireless communication devices using directional beams are communicating. In Figure 18, the multiple wireless communication devices are shown as base station device 1 and terminal device 2. Beamforming is performed by each wireless communication device selecting a candidate beam from a plurality of candidate beams that are generated in advance, either fixedly or adaptively, so as to maximize the received power of the signal transmitted and received between it and the opposing wireless communication device. Candidate beam selection is generally performed by transmitting a pre-known signal with synchronized timing between the sender and receiver for each combination of candidate beams, and is generally performed at a predetermined period to track changes in the propagation environment and the movement of the wireless communication devices.

[0005] International Publication No. 2022 / 024241

[0006] Takiha et al., “Standardization Trends and Elemental Technologies of Millimeter-Wave Wireless LAN Systems,” IEICE Communications Society Magazine, Autumn 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 60GHz Band” (IEEE Std 802.11ad-2012), December 28, 2012.

[0007] In wireless communication systems using high-frequency bands, communication is performed using directional beams, which presents a challenge in that the wireless transmission characteristics deteriorate rapidly due to misalignment of the antenna orientations of the wireless communication devices involved in the communication, or the presence of obstacles in the communication path. Figure 19 shows an example of a wireless communication system in which a base station device 1 installed on the ground and a terminal device 2 installed on a robotic cart R are communicating. In the situation shown in Figure 19, the antennas of the base station device 1 and the terminal device 2 are facing each other directly, so high-quality wireless communication can be expected.

[0008] On the other hand, as shown in Figure 20, it is expected that as the robot cart R moves, the antennas of the base station device 1-1 and the terminal device 2 will no longer be directly facing each other. For example, under the conditions shown in Figure 20, it is difficult for the antennas of the base station device 1-1 and the terminal device 2 to directly see the antenna of the opposing wireless communication device. Under such conditions, if a reflective object W, such as the wall shown in Figure 20, is present, it may be possible to communicate through the reflection path shown by the dotted line, but if the reflective object W is not present, communication is not possible.

[0009] Furthermore, depending on the material of the reflector W, radio waves may be absorbed, resulting in degraded communication quality compared to when the antenna is directly facing the device. Thus, in the high-frequency band, the combination of antenna orientations of wireless communication devices can significantly degrade communication characteristics and lead to unstable communication, posing a challenge for the system.

[0010] By the way, under conditions where many base station devices 1 are installed, as shown in Figure 20, it is conceivable that another base station device may exist in the direction of the antenna of the terminal device 2 as the robot cart R moves. For example, in Figure 20, base station device 1-2 exists as another base station device. However, a typical terminal device, when connected to a specific base station device, tends to consider the connected base station device as the best quality and tries to maintain the connection.

[0011] As shown in Figure 21, let's assume that base station device 1-1 and terminal device 2 are connected. Subsequently, as the robot cart R moves, the antenna direction of terminal device 2 changes, changing from the state shown in Figure 21 to the state shown in Figure 22. Finally, let's assume that the antenna direction of terminal device 2 is pointed towards base station device 1-2, as shown in Figure 23. Even in this case, terminal device 2 will attempt to communicate with base station device 1-1 with the beam out of focus. Therefore, terminal device 2 may not attempt to connect with base station device 1-2 until the connection with base station device 1-1 has been completely severed. In other words, terminal device 2 may only be able to connect with base station device 1-2 after detecting that the connection with base station device 1-1 has been completely severed.

[0012] In such cases, there was a problem in that communication interruptions occurred due to a temporary deterioration in communication quality between the upstream network connected to the base station device 1 and the terminal device 2.

[0013] In view of the above circumstances, the present invention aims to provide a technology that can suppress communication interruptions.

[0014] One aspect of the present invention is a wireless communication device comprising: a surrounding environment information collection unit that collects quality information representing the quality of wireless communication for each combination of a wireless communication device located in the vicinity and each of the possible candidate beams; a communication control unit that weights the quality information collected by the surrounding environment information collection unit using a weighting coefficient that makes it easier to select a candidate beam closer to the center among the possible candidate beams, and selects a wireless communication device to communicate with based on the weighted quality information; and a wireless communication unit that wirelessly connects with the selected wireless communication device to communicate with.

[0015] One aspect of the present invention is a wireless communication system comprising a first communication device and one or more second communication devices that communicate with the first communication device, wherein the first communication device comprises a surrounding environment information collection unit that collects quality information representing the quality of wireless communication for each combination of the one or more second communication devices located in the vicinity and each of the candidate beams that can be formed; a communication control unit that weights the quality information collected by the surrounding environment information collection unit using a weighting coefficient that makes it easier to select a candidate beam closer to the center among the candidate beams that can be formed, and selects a second wireless communication device to communicate with based on the weighted quality information; and a wireless communication unit that wirelessly connects with the selected second wireless communication device to communicate with, wherein the one or more second communication devices communicate with the first communication device.

[0016] One aspect of the present invention is a wireless communication method that collects quality information representing the quality of wireless communication for each combination of a wireless communication device located in the vicinity and each of the possible candidate beams, weights the collected quality information using a weighting coefficient that makes it easier to select a candidate beam closer to the center from among the possible candidate beams, selects a wireless communication device to communicate with based on the weighted quality information, and establishes a wireless connection with the selected wireless communication device.

[0017] One aspect of the present invention is a computer program that causes a computer to perform the following steps: a surrounding environment information collection step of collecting quality information representing the quality of wireless communication for each combination of a wireless communication device located in the vicinity and each of the candidate beams that can be formed; a communication control step of weighting the quality information collected in the surrounding environment information collection step using a weighting coefficient that makes it easier to select a candidate beam closer to the center from among the candidate beams that can be formed, and selecting a wireless communication device to communicate with based on the weighted quality information; and a wireless communication step of wirelessly connecting with the selected wireless communication device to communicate with.

[0018] This invention makes it possible to suppress communication interruptions.

[0019] A diagram showing a configuration example of a wireless communication system in the first embodiment. A diagram showing an example of a candidate beam in the first embodiment. A diagram showing an example of a quality information table in the first embodiment. A diagram showing an example of a weighting table in the first embodiment. A diagram showing the result of the weighted quality information in the first embodiment. A diagram showing a configuration example of a wireless communication device in the first embodiment. A flowchart showing the processing flow of the wireless communication device in the first embodiment. A diagram showing an example of a quality information table in the second embodiment. A diagram showing the time-series change of each wireless communication device in the second embodiment. A diagram showing an example of a weighting table in the second embodiment. A diagram showing the result of the weighted quality information in the second embodiment. A flowchart showing the processing flow of the wireless communication device in the second embodiment. A diagram showing a configuration example of a wireless communication device in the third embodiment. A diagram showing an example of candidate beams of a plurality of wireless communication units in the third embodiment. A diagram showing an example of a quality information table in the third embodiment. A diagram showing the result of the weighted quality information in the third embodiment. A flowchart showing the processing flow of the wireless communication device in the third embodiment. A conceptual diagram showing a state in which a plurality of wireless communication devices using directional beams are communicating. A diagram showing 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 R are communicating. A diagram for explaining problems occurring in the communication between a base station device installed on the ground and a terminal device installed on a robot cart. A diagram for explaining conventional problems. A diagram for explaining conventional problems. A diagram for explaining conventional problems.

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] (First Embodiment) FIG. 1 is a diagram showing a configuration example of a wireless communication system 100 in the first embodiment. The wireless communication system 100 includes one wireless communication device 10 and a plurality of wireless communication devices 20-1 to 20-3. The wireless communication device 10 and each wireless communication device 20 communicate wirelessly. In FIG. 1, a configuration in which the wireless communication system 100 includes three wireless communication devices 20 is shown, but the wireless communication system 100 may include two or more wireless communication devices 20.

[0022] The wireless communication device 10 performs wireless communication with an opposing wireless communication device 20. The wireless communication device 10 is, for example, a terminal device. The wireless communication device 10 can form directive beams in different directions. A directive beam is a beam having directivity in a specific direction. Hereinafter, the directive beams that the wireless communication device 10 can form in different directions are described as candidate beams. In FIG. 1, as an example, a configuration in which the wireless communication device 10 can form candidate beams B1 to B9 in nine directions with different angles is shown, but the number of candidate beams that the wireless communication device 10 can form is not particularly limited. In the following description, a case where the number of candidate beams that the wireless communication device 10 can form is nine is described as an example.

[0023] Further, the wireless communication device 10 is held in a state where the direction of the antenna changes due to rotation or the like. For example, the wireless communication device 10 may be arranged on the robot cart R as described in FIG. 19, or may be held by a person.

[0024] The wireless communication device 20 performs wireless communication with the wireless communication device 10. The wireless communication device 20 is, for example, a base station device. The wireless communication device 20 receives a signal transmitted from the wireless communication device 10 and transmits a response to the received signal to the wireless communication device 10.

[0025] In the following description, a case where the wireless communication device 10 is a terminal device and the wireless communication device 20 is a base station device is described, but the wireless communication device 10 may be a base station device and the wireless communication device 20 may be a terminal device.

[0026] Figure 1 shows a configuration in which the wireless communication device 10 selects candidate beam B5 and communicates with the wireless communication device 20-2. As mentioned above, communication using reflection paths in the high-frequency band has the problem of communication quality degrading easily and communication becoming unstable, so it is assumed that communication using line-of-sight waves will be utilized as shown in Figure 1. If the wireless communication device 10 has nine candidate beams as shown in Figure 1, the beam radiation direction is shown as an example in Figure 2.

[0027] Figure 2 shows an example of a candidate beam in the first embodiment. As shown in Figure 2, the beam's radiation direction (radiation angle) is determined in association with the beam ID, which is the identifier of the candidate beam. In this way, the candidate beams that the wireless communication device 10 can form can be associated with the beam ID and the radiation direction of the candidate beam identified by the beam ID. That is, depending on which candidate beam is used, the direction of the opposing wireless communication device 20 with which the wireless communication device 10 is communicating can be determined. Furthermore, when communicating using a reflection path, the direction of the reflective object can be determined.

[0028] In the example shown in Figure 2, the radiation direction of candidate beam B5, identified by beam ID "5", is "0°". Therefore, candidate beam B5, identified by beam ID "5", is a beam that radiates at an angle of 0° from the surface of the antenna of the wireless communication device 10. In the following explanation, candidate beam B5 will be described as the central beam. The other candidate beams radiate at predetermined angles from the surface of the antenna of the wireless communication device 10.

[0029] The wireless communication device 10 scans the surrounding environment at predetermined intervals or at arbitrary timings to check whether there are other wireless communication devices 20 besides the connected opposing wireless communication device 20. In the example shown in Figure 1, the wireless communication device 10 scans the surrounding environment to check whether there are other wireless communication devices 20 besides the connected opposing wireless communication device 20-2. At this time, the wireless communication device 10 scans the surrounding environment with each candidate beam. In this way, the wireless communication device 10 collects quality information of the communication environment between the wireless communication device 10 and each wireless communication device 20 located in its vicinity by scanning the surrounding environment with each candidate beam.

[0030] Quality information refers to information relating to the quality of wireless communication. For example, it may be the received signal strength indication (RSSI) of a reference signal transmitted from another wireless communication device 20, obtained when the wireless communication device 10 selects a directional beam; the signal-noise ratio (SNR) obtained by estimating the received signal power and noise; information to identify which directional beam was used, such as the ID of the directional beam actually used for communication; or information on the transmission distance obtained by a distance estimation function (for example, RTT: estimation of transmission distance based on round-trip time), or any combination thereof. In the following explanation, the quality information will be assumed to be the received signal strength indication (RSSI).

[0031] The wireless communication device 10 stores quality information obtained by scanning the surrounding environment, associating it with the opposing device ID and the beam ID of each candidate beam of the wireless communication device 10 that performed the scan. For example, as shown in Figure 3, the wireless communication device 10 stores the information in a table format, associating the opposing device ID with each beam ID. Hereinafter, the table associating the opposing device ID with each beam ID will be referred to as the quality information table. The opposing device ID represents the identifier of a wireless communication device 20 that can be the opposing device (including the wireless communication device 20 that is currently connected). Note that Figure 3 shows an example where quality information is obtained for all candidate beams for one wireless communication device 20, but depending on the position of the wireless communication device 20, quality information may not be obtained for some candidate beams. In this case, "-" or the like will be registered for the items for which quality information was not obtained.

[0032] In Figure 3, the IEEE 802.11ad BSSID (Basic Service Set Identifier) ​​string is shown as an example for the opposing device ID. However, any identifier that can identify the wireless communication device 20 that may be the opposing device can be used. Similarly, the beam ID is shown as an example of a string representing the beam ID (e.g., 1, 2, 3, ..., 9). However, any information that can identify the candidate beam can be used. For example, a combination of the beam ID and the identifier of the wireless communication device 10 may be used.

[0033] In the example shown in Figure 3, the quality information table registers quality information corresponding to three combinations of opposing device IDs and beam IDs. The three opposing device IDs are, for example, opposing device ID "xx:xx:xx:xx:xx:xx" (hereinafter referred to as "xx" for simplicity), opposing device ID "xx:xx:xx:xx:xx:xy" (hereinafter referred to as "xy" for simplicity), and opposing device ID "xx:xx:xx:xx:xx:xz" (hereinafter referred to as "xz" for simplicity). In the following explanation, the wireless communication device 20 identified by opposing device ID "xx" will be referred to as wireless communication device 20-x, the wireless communication device 20 identified by opposing device ID "xy" will be referred to as wireless communication device 20-y, and the wireless communication device 20 identified by opposing device ID "xz" will be referred to as wireless communication device 20-z.

[0034] Referring to the quality information table shown in Figure 3, among the quality information for each beam ID corresponding to the opposing device ID "xy", the quality of candidate beam B2, identified by beam ID "2", is the best. Therefore, it is common practice for the wireless communication device 10 to control the wireless communication device 20-y to communicate using candidate beam B2.

[0035] However, as described above, among the multiple candidate beams that the wireless communication device 10 can form, the candidate beams closer to the edges (for example, candidate beams "1", "2", "8", "9", etc.) may have their communication paths shifted further outward due to the rotation of the wireless communication device 10, potentially degrading the transmission characteristics. Therefore, it is more likely that the degradation of transmission characteristics can be avoided by not connecting to the opposing wireless communication device 20, which is likely to communicate using candidate beams closer to the edges.

[0036] Therefore, the wireless communication device 10 weights all quality information obtained by scanning so that it can preferentially connect to wireless communication device 20 that is less likely to have its transmission characteristics degraded. That is, the wireless communication device 10 weights the quality information obtained for each combination of each wireless communication device 20 and each candidate beam that may be the opposing device. It is preferable to set the weighting coefficient (hereinafter referred to as the "weighting coefficient") taking into account the wireless communication device 10 and its directivity. Therefore, in the first embodiment, the weighting coefficient is set so that candidate beams closer to the center are selected rather than candidate beams closer to the edges.

[0037] Therefore, the wireless communication device 10 maintains the weighting table shown in Figure 4. Figure 4 is a diagram showing an example of the weighting table in the first embodiment. In the weighting table shown in Figure 4, a weight coefficient is associated with each beam ID. For example, as shown in Figure 4, the weight coefficient for beam IDs "4" to "6" is "1", and the weight coefficient for beam IDs "1" and "9" is "0.001". In this way, the weighting coefficients in the weighting table shown in Figure 4 are set such that the weight coefficients of candidate beams closer to the center are higher and the weight coefficients of candidate beams closer to the edges are lower among the multiple candidate beams that the wireless communication device 10 can form. In other words, the weighting table shown in Figure 4 is set with weight coefficients such that the candidate beams closer to the center are more likely to be selected among the candidate beams that the wireless communication device 10 can form. Note that the weight coefficients shown in Figure 4 are just an example, and it is sufficient that the weight coefficient of the candidate beam closer to the center is higher (larger) than the weight coefficient of the candidate beam closer to the edges.

[0038] Of the multiple candidate beams that the wireless communication device 10 can form, the candidate beam closest to the center is less likely to have its communication path changed even if the direction of the antenna changes due to the rotation of the wireless communication device 10, etc. Therefore, it is desirable to make the weighting coefficient of the candidate beam closest to the center larger than that of the candidate beam closest to the edge, so that the candidate beam closest to the center is more likely to be selected. Conversely, of the multiple candidate beams that the wireless communication device 10 can form, the candidate beam closest to the edge is more likely to have its communication path changed due to the rotation of the wireless communication device 10, etc., as described above. Therefore, it is desirable to make the weighting coefficient of the candidate beam closest to the edge smaller than that of the candidate beam closest to the center, so that the candidate beam closest to the edge is less likely to be selected.

[0039] Here, a candidate beam near the center is a candidate beam whose radiation direction is less than or equal to a first angle (for example, ±10 degrees or less) relative to the central beam. A candidate beam near the edge is a candidate beam whose radiation direction is greater than or equal to a second angle (for example, ±30 degrees or more) relative to the central beam. The first angle has a smaller absolute value than the second angle. Note that the definitions of candidate beams near the center and near the edge are just examples; it is sufficient if the beams can be classified into at least two categories (at least candidate beams near the center and candidate beams near the edge) based on some criterion.

[0040] Figure 5 shows the result of the wireless communication device 10 weighting the quality information shown in Figure 3 using the weighting table shown in Figure 4. Figure 5 is a diagram showing the result of the weighted quality information. An example of weighting will be explained here. Since the weighting method is the same for all devices, the example will be given to the opposing device ID "xx". First, the wireless communication device 10 converts the dB value (decibels) to the true value. As shown in Figure 3, the quality information for beam ID "1" for opposing device ID "xx" is -80 dBm. Therefore, -80 dBm = 0.00000001 mW. Next, the wireless communication device 10 multiplies the converted true value by the weighting coefficient. From the weighting table shown in Figure 4, the weighting coefficient for beam ID "1" is "0.001". Therefore, 0.00000001 × 0.001 = 0.00000000001 mW. Then, the wireless communication device 10 converts the weighted true value back to the dB value. Therefore, 0.00000000001mW = -110dBm.

[0041] The wireless communication device 10 performs the above-described process for all combinations of opposing devices and quality information. Here, as an example, a configuration is shown in which the decibel value is converted to a true value and then multiplied by a weighting coefficient. Note that converting back to a true value and multiplying by a weighting coefficient is not particularly necessary. As shown in Figure 5, after weighting, the wireless communication device 20 with the best quality becomes candidate beam B5 with beam ID "5" for wireless communication device 20-x. Since candidate beam B5 is the central beam, even if the wireless communication device 10 itself rotates, it can use nearby candidate beams, reducing the probability of communication interruption.

[0042] Therefore, the wireless communication device 10 switches its connection to connect with wireless communication device 20-x using candidate beam B5. Even after weighting, if the wireless communication device 20 with the best quality is the currently connected wireless communication device 20, the wireless communication device 10 continues its connection with the currently connected wireless communication device 20. By performing the above process, communication interruptions can be suppressed. The specific configuration for realizing the above process will be described below.

[0043] (Configuration of the wireless communication device 10) Figure 6 shows an example of the configuration of the wireless communication device 10 in the first embodiment. The wireless communication device 10 comprises a data processing unit 11, a wireless communication unit 12, a surrounding environment information collection unit 13, a communication control unit 14, and an antenna 15.

[0044] The data processing unit 11 performs data input and output with a higher-level device or other base station located above the wireless communication device 10. For example, the data processing unit 11 transmits signals received from the wireless communication device 20 to the higher-level device or other base station. For example, the data processing unit 11 receives signals destined for the wireless communication device 20 from the higher-level device or other base station.

[0045] The wireless communication unit 12 controls the amplitude or phase of the antenna 15 according to the instructions of the communication control unit 14 to form directional beams in different directions. In this way, the wireless communication unit 12 switches the directional beams and transmits signals according to the instructions of the communication control unit 14. The wireless communication unit 12 receives signals (e.g., responses) transmitted from the wireless communication device 20 via the antenna 15.

[0046] Furthermore, the wireless communication unit 12 scans the surrounding radio waves according to instructions from the communication control unit 14. For example, the wireless communication unit 12 scans the surrounding radio waves by switching the directional beam. In this way, the wireless communication unit 12 searches for other wireless communication devices 20 located around the wireless communication device 10. Hereinafter, the process performed by the wireless communication unit 12 to search for other wireless communication devices 20 will be referred to as the scanning operation.

[0047] The surrounding environment information collection unit 13 collects quality information for each candidate beam of wireless communication devices 20 located around the wireless communication device 10 as a result of the scan operation performed by the wireless communication unit 12. The surrounding environment information collection unit 13 also collects information necessary for connecting and communicating with the wireless communication devices 20 (hereinafter referred to as "connection information"). For example, the surrounding environment information collection unit 13 collects the received signal strength of signals transmitted from wireless communication devices 20 located around the wireless communication device 10 as quality information. The connection information includes, for example, the identifier of the wireless communication device 20, specifically the BSSID (Basic Service Set Identifier) ​​for a wireless LAN (Local Area Network), the cell ID for 5G, etc. The surrounding environment information collection unit 13 stores the collected quality information for each candidate beam in a quality information table, associating it with the ID of the wireless communication device 20.

[0048] The communication control unit 14 controls the wireless communication unit 12. The communication control unit 14 instructs the wireless communication unit 12 to perform a scan operation, for example, at a predetermined period or at any arbitrary timing. The communication control unit 14 maintains a weighting table and weights the quality information for each candidate beam registered in the quality information table. Based on the weighting results, the communication control unit 14 controls the wireless communication unit 12 to instruct it to connect to a wireless communication device 20 (hereinafter referred to as "new connection destination device") whose quality information meets predetermined conditions indicating good communication quality.

[0049] The predetermined condition is, for example, that if the quality information is the received signal strength, then the received signal strength is the best. However, the predetermined condition is not limited to this; for example, if the quality information is the received signal strength, then the received signal strength may be above a threshold, or if the quality information is the signal-to-noise power ratio, then the signal-to-noise power ratio may be above a threshold. If there are multiple candidates for the new connection destination device, the communication control unit 14 may select the wireless communication device 20 with the best communication quality from among the candidates, or it may select the wireless communication device 20 that can communicate using the candidate beam closest to the center.

[0050] Antenna 15 is provided in correspondence with the wireless communication unit 12. Antenna 15 forms directional beams in different directions according to the control of the wireless communication unit 12. Antenna 15 transmits signals by radiating radio waves using the formed directional beams. Antenna 15 receives radio waves transmitted from the wireless communication device 20 using the formed directional beams.

[0051] (Operation of the wireless communication device 10) Figure 7 is a flowchart showing the processing flow of the wireless communication device 10 in the first embodiment. In the explanation of Figure 7, it is assumed that the wireless communication unit 12 of the wireless communication device 10 is connected to a certain wireless communication device 20.

[0052] The communication control unit 14 instructs the wireless communication unit 12 to perform a scan operation at a predetermined interval or at any arbitrary timing (step S101). The wireless communication unit 12 controls the antenna 15 in accordance with the instructions of the communication control unit 14 and scans the surrounding environment according to the procedure defined in the communication method (step S102). For example, the wireless communication unit 12 scans the surrounding environment by controlling the antenna 15 to sequentially emit candidate beams B1 to B9.

[0053] The surrounding environment information collection unit 13 collects quality information of wireless communication devices 20 located around the wireless communication device 10 for each candidate beam as a result of the scan operation performed by the wireless communication unit 12 (step S103). For example, suppose the wireless communication unit 12 scans the surrounding environment by controlling the antenna 15 to emit a candidate beam B1. If a wireless communication device 20 is located in the direction of the candidate beam B1, the surrounding environment information collection unit 13 collects quality information with the wireless communication device 20 located in the direction of the candidate beam B1. For example, if a wireless communication device 20-1 is located in the direction of the candidate beam B1, the surrounding environment information collection unit 13 collects quality information with the wireless communication device 20-1 located in the direction of the candidate beam B1. The surrounding environment information collection unit 13 then stores the collected quality information in a quality information table, associating it with the beam ID "1" of the candidate beam B1 and the wireless communication device 20-1 that is the source of the quality information.

[0054] Furthermore, if multiple wireless communication devices 20 exist in the direction of candidate beam B1, the surrounding environment information collection unit 13 collects quality information for each wireless communication device 20. For example, if wireless communication devices 20-1 and 20-2 exist in the direction of candidate beam B1, the surrounding environment information collection unit 13 collects quality information with each of the wireless communication devices 20-1 and 20-2 that are located in the direction of candidate beam B1. The surrounding environment information collection unit 13 then stores the quality information collected with wireless communication device 20-1 in a quality information table, associating it with the beam ID "1" of candidate beam B1 and the wireless communication device 20-1 that is the source of the quality information. Similarly, the surrounding environment information collection unit 13 stores the quality information collected with wireless communication device 20-2 in a quality information table, associating it with the beam ID "1" of candidate beam B1 and the wireless communication device 20-2 that is the source of the quality information.

[0055] The communication control unit 14 determines whether or not a scan operation has been performed on all candidate beams (step S104). If the communication control unit 14 determines that a scan operation has not been performed on all candidate beams (step S104-NO), the wireless communication device 10 repeats the processing from step S101 onwards. In this case, the wireless communication device 10 performs a scan operation on the candidate beams that have not yet been scanned. In this way, the wireless communication device 10 performs a scan operation on all candidate beams by repeatedly executing the processing from step S101 to step S103. As a result, the wireless communication device 10 can generate a quality information table in which the quality information obtained from all candidate beams is registered. Hereafter, it will be explained assuming that the information shown in Figure 3 is registered in the quality information table.

[0056] If the communication control unit 14 determines that a scan operation has been performed on all candidate beams (step S104-YES), the communication control unit 14 refers to the weighting table it holds and weights the quality information for each candidate beam registered in the quality information table (step S105). Specifically, the communication control unit 14 first obtains the weight coefficient associated with the beam ID in the weighting table. For example, the communication control unit 14 obtains the weight coefficient "0.001" associated with beam ID "1" in the weighting table shown in Figure 4.

[0057] Next, the communication control unit 14 refers to the quality information table and multiplies the weight coefficient by the quality information registered in the item that matches the beam ID of the acquired weight coefficient. For example, the communication control unit 14 refers to the quality information table and multiplies the weight coefficient "0.001" by the weight coefficient "0.001" for each of the quality information entries "-80", "-60", and "-80" that match the beam ID "1" of the acquired weight coefficient "0.001". The communication control unit 14 performs the above process for all of the quality information registered in the quality information table.

[0058] Subsequently, the communication control unit 14 refers to the quality information table and identifies the wireless communication device 20 whose quality information meets predetermined conditions from all the weighted quality information. The communication control unit 14 determines whether the identified wireless communication device 20 whose quality information meets predetermined conditions and the wireless communication unit 12 are currently connected (step S106). If the communication control unit 14 determines that the identified wireless communication device 20 whose quality information meets predetermined conditions and the wireless communication unit 12 are currently connected (step S106-YES), the wireless communication device 10 maintains the current connection and waits for a certain period of time (step S107). After a certain period of time has elapsed, the wireless communication device 10 executes the processes from step S101 onwards.

[0059] On the other hand, if the communication control unit 14 determines that the wireless communication device 20 and the wireless communication unit 12 that meet the specified quality information conditions are not currently connected (step S106-NO), the communication control unit 14 instructs the wireless communication unit 12 to connect to a wireless communication device 20 (new connection device) that meets the specified conditions. At this time, the communication control unit 14 instructs the wireless communication unit 12 to connect to the new connection device using a candidate beam identified by a beam ID that meets the specified conditions.

[0060] The wireless communication unit 12 connects to the new connection device using a candidate beam identified by a beam ID that satisfies predetermined conditions, in accordance with instructions from the communication control unit 14 (step S108). After that, the wireless communication device 10 waits for a certain period of time (step S107). After the period of time has elapsed, the wireless communication device 10 executes the processes from step S101 onwards.

[0061] The wireless communication device 10 configured as described above includes: a surrounding environment information collection unit 13 that collects quality information representing the quality of wireless communication for each combination of wireless communication devices 20 located in the vicinity and each of the possible candidate beams; a communication control unit 14 that weights the collected quality information using a weighting coefficient that makes it easier to select a candidate beam closer to the center among the possible candidate beams, and selects a wireless communication device 20 to communicate with based on the weighted quality information; and a wireless communication unit 12 that wirelessly connects with the selected wireless communication device 20 to communicate with.

[0062] As a result, among the candidate beams that the wireless communication device 10 can form, candidate beams closer to the center are more likely to be selected than candidate beams closer to the edges. Candidate beams closer to the edges may cause temporary communication interruptions due to rotation of the wireless communication device 10, etc. On the other hand, candidate beams closer to the center allow communication to continue using other candidate beams even if the wireless communication device 10 rotates, etc. Therefore, the wireless communication device 10 instructs the wireless communication unit 12 to connect to a wireless communication device 20 that can be connected using a candidate beam closer to the center. This makes it possible to preferentially connect to wireless communication devices 20 located in the direction of the center of the antenna plane. In this way, the wireless communication device 10 can switch the connection in advance to a wireless communication device 20 that is expected to be less likely to experience communication interruptions, in order to avoid temporary communication interruptions that may occur due to rotation of the wireless communication device 10, etc. Therefore, it becomes possible to suppress communication interruptions. As a result, communication stability can be expected.

[0063] (Second Embodiment) In the first embodiment, a configuration was described in which a fixed weight is set at the ends of the candidate beams, and control is performed so that candidate beams closer to the center are selected rather than candidate beams closer to the ends. In the second embodiment, a configuration is described in which a wireless communication device directed toward the center of the candidate beam is selected, and control is performed to connect to the selected wireless communication device. The system configuration and the configuration of the wireless communication device in the second embodiment are the same as in the first embodiment.

[0064] As described above, when selecting a wireless communication device that is directed towards the center of the candidate beam, it is necessary to store the information obtained by the scanning operation in a time series and extract the change in direction of each wireless communication device 20. For example, when wireless communication device 10 is directed towards time = t ０ From time = t ３ Assume that the quality information obtained up to this point is retained. Time = t ０ From time = t ３ The quality information obtained up to this point is shown in Figure 8. Figure 8(A) is time = t ０ This represents the quality information obtained from the scan operation performed at the timing, and Figure 8(B) shows time = t １represents the quality information obtained by the scan operation executed at the timing of ２ and (C) of FIG. 8 represents the quality information obtained by the scan operation executed at the timing of time = t ３ and represents the quality information obtained by the scan operation executed at the timing of

[0065] As shown in (A) to (D) of FIG. 8, when the quality information changes, if the directions of the candidate beams with the best quality information for each wireless communication device 20 at each time are arranged in time series, FIG. 9 is obtained. As shown in FIG. 9, it can be seen that the wireless communication device 20-x moves outward from the front (beam direction 0°) of the antenna of the wireless communication device 10 as time passes. On the other hand, it can be seen that the wireless communication device 20-y moves toward the front (beam direction 0°) of the antenna of the wireless communication device 10 as time passes.

[0066] At the time = t shown in (C) of FIG. 8 ２ the wireless communication device 20-x has the best quality information. However, as described above, it is predicted that the wireless communication device 20-x will move outside the beam ID "9" as time passes, and the transmission characteristics will deteriorate. Therefore, the communication is stabilized by switching the connection to the wireless communication device 20-y at an early stage.

[0067] Therefore, the wireless communication device 10 in the second embodiment holds the weighting table shown in FIG. 10. FIG. 10 is a diagram showing an example of the weighting table in the second embodiment. In the weighting table shown in FIG. 10, weighting coefficients are set for the changing directions of the directivity based on the time-series changes of each wireless communication device 20. For example, as shown in FIG. 10, when the directivity changes outward, the weighting coefficient is "0.1", when the directivity changes inward, the weighting coefficient is "10", and when the directivity does not change, the weighting coefficient is "1".

[0068] A change in directivity outward occurs when the position of the wireless communication device 20 moves away from the front of the antenna of the wireless communication device 10 as time progresses. In other words, a change in directivity outward occurs when the position of the wireless communication device 20 moves away from the central beam of the wireless communication device 10 as time progresses. A change in directivity inward occurs when the position of the wireless communication device 20 moves towards the front of the antenna of the wireless communication device 10 as time progresses. In other words, a change in directivity inward occurs when the position of the wireless communication device 20 moves towards the central beam of the wireless communication device 10 as time progresses. Therefore, the weighting table shown in Figure 10 is set with weighting coefficients such that the candidate beam closest to the center is more likely to be selected from among the candidate beams that the wireless communication device 10 can form.

[0069] The wireless communication device 10 uses the weighting table shown in Figure 10 to weight the quality information shown in Figure 8. The result of weighting the quality information is shown in Figure 11. In Figure 11, time = t １ This shows the results of weighting the quality information obtained at the timing. In this case, the wireless communication device 10 is at time = t ０ and time = t １ The weighting coefficient is determined based on the change in the directional beam. For example, as explained using Figure 8, the wireless communication device 20-x operates at time = t ０ At this timing, beam ID "5" has the best quality information, and time = t １ At that timing, beam ID "6" has the best quality information.

[0070] In other words, it is assumed that the wireless communication device 20-x is moving in the direction of the radiation direction of the candidate beam of the wireless communication device 10 from "0°" to "10°". As a result, the wireless communication device 10 determines that the directivity has changed outward. Therefore, the wireless communication device 10 multiplies the quality information obtained with the wireless communication device 20-x by a weighting coefficient of "0.1" which is associated with "directivity changes outward" in the weighting table.

[0071] Similarly, for the wireless communication device 20-y, time = t０ At this timing, beam ID "2" has the best quality information, and time = t １ At this timing, beam ID "3" has the best quality information. That is, it is assumed that the wireless communication device 20-y has moved from the radiation direction of the candidate beam of the wireless communication device 10 in the direction of "-30°" to "-20°". As a result, the wireless communication device 10 determines that the directivity has changed inward. Therefore, the wireless communication device 10 multiplies the quality information obtained with the wireless communication device 20-y by the weighting coefficient "10" which is associated with "directivity changes inward" in the weighting table.

[0072] Similarly, the wireless communication device 20-z has time = t ０ At this timing, beam ID "7" has the best quality information, and time = t １ At this timing, beam ID "8" has the best quality information. That is, it is assumed that the wireless communication device 20-z has moved in the direction of the radiation direction of the candidate beam of the wireless communication device 10 from "20°" to "30°". As a result, the wireless communication device 10 determines that the directivity has changed outward. Therefore, the wireless communication device 10 multiplies the quality information obtained with the wireless communication device 20-z by the weighting coefficient "0.1" which is associated with "directivity changes outward" in the weighting table.

[0073] By performing the above process for all wireless communication devices 20, the weighted quality information shown in Figure 11 is obtained. As shown in Figure 11, after weighting, the wireless communication device 20 with the best quality becomes candidate beam B3 with beam ID "3" for wireless communication device 20-y. Wireless communication device 10 can then switch connections.

[0074] (Operation of the wireless communication device 10 in the second embodiment) Figure 12 is a flowchart showing the processing flow of the wireless communication device 10 in the second embodiment. In the explanation of Figure 12, it is assumed that the wireless communication unit 12 of the wireless communication device 10 is connected to a certain wireless communication device 20. In Figure 12, the same reference numerals as in Figure 7 are used for the same processes as in Figure 7, and their explanation is omitted.

[0075] When the processes from step S101 to step S103 are completed, the communication control unit 14 determines whether or not the scan operation has been performed on all candidate beams a predetermined number of times (step S201). If the communication control unit 14 determines that the scan operation has not been performed on all candidate beams a predetermined number of times (step S201-NO), the wireless communication device 10 repeats the processes from step S101 onwards. In this case, the wireless communication device 10 performs the scan operation on the candidate beams that have not yet been scanned. Furthermore, if the wireless communication device 10 has performed the scan operation on all candidate beams, it performs the scan operation on all candidate beams a predetermined number of times.

[0076] In this way, the wireless communication device 10 repeats the process from step S101 to step S103 for all candidate beams the number of times the process is performed, so that different times (for example, time = t) ０ ~t ３ The scanning operation is performed on all candidate beams at different times (for example, time = t). As a result, the wireless communication device 10 performs a scan operation on all candidate beams at different times (for example, time = t). ０ ~t ３ In this process, a quality information table containing the quality information obtained from all candidate beams can be generated for each time the scan operation was performed. Hereafter, the quality information table will be described assuming that the information shown in Figure 8 is registered in it.

[0077] If the communication control unit 14 determines that the scan operation has been performed on all candidate beams a predetermined number of times (step S201-YES), the communication control unit 14 refers to the weighting table it holds and weights the quality information for each candidate beam registered in the latest quality information table (step S202). Here, the latest quality information table is the quality information table generated based on the quality information obtained from the most recent scan operation. As described above, time = t ０ ~t ３ If the scan operation is performed at each respective timing, then time = t ３ This is a quality information table generated based on quality information obtained from a scan operation performed at a specific time.

[0078] First, the communication control unit 14 refers to a quality information table for each time period and extracts the direction of the candidate beam with the best quality information for each wireless communication device 20 at each time period. This allows the communication control unit 14 to extract information such as that shown in Figure 9. Based on the extracted information indicating the direction of the candidate beam with the best quality information for each wireless communication device 20 at each time period, the communication control unit 14 identifies the direction of change in directivity based on the time-series changes of each wireless communication device 20. For example, the communication control unit 14 identifies whether the directivity is changing outward, inward, or unchanged for each wireless communication device 20. At this time, the communication control unit 14 identifies whether the directivity is changing outward, inward, or unchanged. ０ From time t ３ You can make a judgment based on the change in beam direction up to the latest time t ３ and the time t that is one time before the most recent time ２ The decision may also be made based on the change in beam direction. Here, the latest time t ３ and the time t that is one time before the most recent time ２ This will be explained as a judgment based on the change in beam direction.

[0079] The communication control unit 14 refers to its weighting table to obtain a weighting coefficient based on the direction of change in directivity for each identified wireless communication device 20. For example, if the direction of change in directivity based on the time series change of each wireless communication device 20 is as shown in Figure 9, then wireless communication device 20-x is at time t ２ At a time t, the beam is positioned in the direction of "20°". ３ At time t ２ At a time t, the beam is positioned in the direction of "-10°". ３ At time t ２ At a time t, the beam is positioned in the direction of "40°". ３In this configuration, the beam is positioned in the direction of "40°". Therefore, the communication control unit 14 determines that the directivity of the wireless communication device 20-z has not changed.

[0080] Therefore, the communication control unit 14 refers to the weighting table shown in Figure 10 and obtains a weight coefficient of "0.1" for wireless communication device 20-x, a weight coefficient of "10" for wireless communication device 20-y, and a weight coefficient of "1" for wireless communication device 20-z. Next, the communication control unit 14 refers to the most recent quality information table and weights the quality information corresponding to each wireless communication device 20 using the obtained weight coefficients.

[0081] The communication control unit 14 performs weighting by multiplying the quality information for each beam ID corresponding to the wireless communication device 20-x by the acquired weighting coefficient "0.1". The communication control unit 14 performs weighting by multiplying the quality information for each beam ID corresponding to the wireless communication device 20-y by the acquired weighting coefficient "10". The communication control unit 14 performs weighting by multiplying the quality information for each beam ID corresponding to the wireless communication device 20-z by the acquired weighting coefficient "10". After that, the wireless communication device 10 executes the processing from step S106 onwards.

[0082] The wireless communication device 10 in the second embodiment, configured as described above, can achieve the same effects as the first embodiment. Specifically, the wireless communication device 10 in the second embodiment estimates the direction of movement of each wireless communication device 20 based on quality information for each candidate beam obtained at different times, and performs weighting based on the estimated direction of movement. In this case as well, the wireless communication device 10 performs weighting using a weighting coefficient that makes it easier to select candidate beams that are closer to the center among the possible candidate beams. This makes it possible to preferentially connect to wireless communication devices 20 that are moving toward the center of the antenna plane or are located toward the center of the antenna plane. In this way, the wireless communication device 10 can pre-switch the connection to wireless communication devices 20 that are expected to be less likely to experience communication interruptions, in order to avoid temporary communication interruptions that occur due to the rotation of the wireless communication device 10, etc. Therefore, it becomes possible to suppress communication interruptions. As a result, communication stabilization can be expected.

[0083] (Third Embodiment) In the first and second embodiments, a configuration was described in which the wireless communication device has one wireless communication unit and performs wireless communication with one wireless communication device. It is conceivable to provide redundancy of wireless communication links by providing a wireless communication device with multiple wireless communication units and controlling each wireless communication unit to be connected to a different base station device (see, for example, Patent Document 1). Therefore, in the third embodiment, a configuration will be described in which the wireless communication device has multiple wireless communication units and performs wireless communication with multiple wireless communication devices.

[0084] (Configuration of Wireless Communication Device 10a) Figure 13 shows an example of the configuration of the wireless communication device 10a in the third embodiment. The wireless communication device 10a includes a data processing unit 11, a plurality of wireless communication units 12-1, 12-2, a surrounding environment information collection unit 13a, a communication control unit 14a, and a plurality of antennas 15-1, 15-2. Although Figure 13 shows a configuration in which the wireless communication device 10a has two wireless communication units 12 and antennas 15, the wireless communication device 10a may be configured to have three or more wireless communication units 12 and antennas 15.

[0085] The wireless communication device 10a differs from the wireless communication device 10 in that it has a surrounding environment information collection unit 13a and a communication control unit 14a instead of the surrounding environment information collection unit 13 and communication control unit 14, and it has multiple wireless communication units 12 and antennas 15. The differences from the wireless communication device 10 will be explained below.

[0086] The wireless communication units 12-1 and 12-2 control the amplitude or phase of antennas 15-1 and 15-2 according to the instructions of the communication control unit 14a to form directional beams in different directions. In this way, the wireless communication units 12-1 and 12-2 transmit signals by switching the directional beams according to the instructions of the communication control unit 14a. The wireless communication units 12-1 and 12-2 receive signals (for example, responses) transmitted from the wireless communication device 20 via antennas 15-1 and 15-2.

[0087] The surrounding environment information collection unit 13a collects quality information for each candidate beam of wireless communication devices 20 located around the wireless communication device 10a as a result of the scan operation performed by each wireless communication unit 12. The surrounding environment information collection unit 13a also collects connection information. For example, the surrounding environment information collection unit 13a collects the received signal strength of signals transmitted from wireless communication devices 20 located around the wireless communication device 10a as quality information. The surrounding environment information collection unit 13a stores the collected quality information for each candidate beam in a quality information table, associating it with the ID of the wireless communication device 20. In the third embodiment, a scan operation is performed for each wireless communication unit 12. Therefore, the surrounding environment information collection unit 13a generates a quality information table for each wireless communication unit 12.

[0088] The communication control unit 14a controls each wireless communication unit 12. The communication control unit 14a instructs each wireless communication unit 12 to perform a scan operation, for example, at a predetermined period or at any arbitrary timing. The communication control unit 14a maintains a weighting table and weights the quality information for each candidate beam registered in the quality information table. Based on the weighting results, the communication control unit 14a controls each wireless communication unit 12 and instructs it to connect to a new destination device.

[0089] The directional beams of the wireless communication units 12-1 and 12-2 are arranged so that they partially overlap, as shown in Figure 14. Figure 15 shows the quality information obtained by the scanning operation performed by the wireless communication units 12-1 and 12-2, respectively. In Figure 15, time = t ０ and time = t １ This shows an example of the case where the scan operation is performed twice. Figures 15(A) and 15(C) show the wireless communication unit 12-1 at different times (for example, time = t ０ and time = t １ Figures 15(B) and 15(D) show quality information obtained by performing a scan operation at different times (for example, time = t). ０ and time = t １ This represents quality information obtained by performing a scan operation.

[0090] Referring to the quality information table shown in Figure 15, the beam direction changes as the wireless communication device 20-x moves from beam ID "6" to beam ID "7" of the wireless communication unit 12-1, and therefore time = t １ This is also detected in the wireless communication unit 12-2. On the other hand, in the wireless communication unit 12-2, the quality of the wireless communication device 20-y is higher than that of the wireless communication unit 12-1. Therefore, the wireless communication unit 12-2 maintains its connection with the wireless communication device 20-y.

[0091] However, in this case, if the wireless communication device 20-y continues to rotate in the same direction, it may move outside the beam of beam ID "9" and communication may be interrupted. Therefore, it is advisable to switch the connection of the wireless communication unit 12-2 to the wireless communication device 20-x in advance.

[0092] Therefore, the wireless communication device 10a in the third embodiment maintains a weighting table similar to that in the second embodiment. The wireless communication device 10a uses the weighting table shown in Figure 10 to weight the most recent quality information shown in Figure 15. In this case, the opposing wireless communication device 20 whose movement could not be determined by the other wireless communication unit 12 is considered unchanged and multiplied by a weighting coefficient of "1".

[0093] Figure 16 shows the results of weighting the quality information. In Figure 16, time = t １ This shows the results of weighting the quality information obtained at the timing. In Figure 16, the beam with beam ID "1" directed towards wireless communication device 20-x has a higher quality information value than the beam with beam ID "7" directed towards wireless communication device 20-y. Therefore, wireless communication device 10a instructs wireless communication unit 12-2 to switch the connection to wireless communication device 20-x. By doing so, the connection of wireless communication device 20-y with wireless communication is maintained, thereby preventing the deterioration of transmission characteristics caused by the direction of wireless communication device 20-y deviating from the direction of the directional beam of wireless communication unit 12.

[0094] Figure 17 is a flowchart showing the processing flow of the wireless communication device 10a in the third embodiment. In the description of Figure 17, it is assumed that at least one wireless communication unit 12 of the wireless communication device 10a is connected to the wireless communication device 20.

[0095] The communication control unit 14a instructs the wireless communication units 12-1 and 12-2 to perform a scan operation at predetermined intervals or at arbitrary timings (step S301). The wireless communication units 12-1 and 12-2 control the antennas 15-1 and 15-2 in accordance with the instructions of the communication control unit 14a and scan the surrounding environment according to the procedure defined in the communication method (step S202). For example, the wireless communication units 12-1 and 12-2 scan the surrounding environment by controlling the antennas 15-1 and 15-2 to sequentially radiate candidate beams B1 to B9.

[0096] The surrounding environment information collection unit 13a collects quality information of wireless communication devices 20 located around the wireless communication device 10a for each candidate beam as a result of the scan operation performed by the wireless communication units 12-1 and 12-2 (step S303). The communication control unit 14a determines whether or not the scan operation has been performed on all candidate beams a predetermined number of times (step S304). If the communication control unit 14a determines that the scan operation has not been performed on all candidate beams a predetermined number of times (step S304-NO), the wireless communication device 10a repeats the processing from step S301 onwards. In this case, the wireless communication device 10a performs the scan operation on the candidate beams that have not been scanned. Furthermore, if the wireless communication device 10a has performed the scan operation on all candidate beams, it performs the scan operation on all candidate beams a predetermined number of times.

[0097] In this way, the wireless communication device 10a repeatedly performs the processing from step S301 to step S303 for all candidate beams, thereby setting different times (for example, time = t) for each of the wireless communication units 12-1 and 12-2. ０ ~t ３ ) The scanning operation is performed on all candidate beams. As a result, the wireless communication device 10a performs a scanning operation on different times (for example, time = t) in the wireless communication units 12-1 and 12-2 respectively. ０ ~t ３ In this process, a quality information table containing the quality information obtained from all candidate beams can be generated for each time the scan operation is performed. Hereafter, the quality information table will be described assuming that the information shown in Figure 15 is registered in it.

[0098] If the communication control unit 14a determines that the scan operation has been performed on all candidate beams a predetermined number of times (step S304-YES), the communication control unit 14a refers to the weighting table it holds and weights the quality information for each candidate beam registered in the latest quality information table (step S305). First, the communication control unit 14a refers to the quality information table for each time period and identifies the wireless communication device 20 that was able to acquire quality information in each of the multiple wireless communication units 12-1 and 12-2. In the example shown in Figure 15, the wireless communication device 20 that was able to acquire quality information in each of the multiple wireless communication units 12-1 and 12-2 is wireless communication device 20-x.

[0099] Therefore, the communication control unit 14a extracts the direction of the candidate beam with the best quality information at each time point for the wireless communication device 20-x, from which quality information has been acquired by the wireless communication units 12-1 and 12-2, respectively. Based on the extracted information indicating the direction of the candidate beam with the best quality information for the wireless communication device 20-x at each time point, the communication control unit 14a identifies the direction of change in directivity based on the time-series changes of each wireless communication device 20.

[0100] The communication control unit 14a refers to its weighting table and obtains a weighting coefficient based on the direction of change in directivity for each identified wireless communication device 20. For example, the directivity of wireless communication device 20-x is changing outward. Therefore, the communication control unit 14a refers to the weighting table shown in Figure 10 and obtains a weighting coefficient of "0.1" for wireless communication device 20-x. The communication control unit 14a also obtains a weighting coefficient of "1" for wireless communication devices 20 from which quality information could not be obtained by any of the multiple wireless communication units 12-1, 12-2. Next, the communication control unit 14a refers to the most recent quality information table and weights the quality information corresponding to each wireless communication device 20 using the obtained weighting coefficient.

[0101] Subsequently, the communication control unit 14a refers to the quality information table and identifies the wireless communication device 20 whose quality information meets predetermined conditions from all the weighted quality information. The communication control unit 14a determines whether the identified wireless communication device 20 whose quality information meets predetermined conditions and the specific wireless communication unit 12 are currently connected (step S306). If the communication control unit 14a determines that the identified wireless communication device 20 whose quality information meets predetermined conditions and the specific wireless communication unit 12 are currently connected (step S306-YES), the wireless communication device 10a waits for a certain period of time while maintaining the current connection (step S307). After a certain period of time has elapsed, the wireless communication device 10a executes the processing from step S301 onwards.

[0102] On the other hand, if the communication control unit 14a determines that the wireless communication device 20 whose identified quality information meets predetermined conditions and the specific wireless communication unit 12 are not currently connected (step S306-NO), the communication control unit 14a instructs the specific wireless communication unit 12 to connect to the wireless communication device 20 (new connection device) that meets the predetermined conditions. At this time, the communication control unit 14a instructs the specific wireless communication unit 12 to connect to the new connection device using a candidate beam identified by a beam ID that meets the predetermined conditions.

[0103] The specific wireless communication unit 12 connects to the new connection device using a candidate beam identified by a beam ID that satisfies predetermined conditions, in accordance with instructions from the communication control unit 14a (step S308). After that, the wireless communication device 10a waits for a certain period of time (step S307). After the period of time has elapsed, the wireless communication device 10a executes the processes from step S301 onwards.

[0104] With the wireless communication device 10a configured as described above, the same effects as in the second embodiment can be obtained even when there are multiple wireless communication units 12.

[0105] (Variation) The multiple wireless communication units 12 provided in the wireless communication device 10a may conform to the same wireless communication standard, or each may correspond to a different wireless communication standard.

[0106] (Modification 1 common to the first to third embodiments) The configurations shown in each embodiment are applicable to any wireless communication system. That is, whether it is an autonomous distributed wireless communication system such as IEEE 802.11ad or a centralized controlled wireless communication system such as 5G (5th Generation) or 5G NR (New Radio), the present invention is similarly applicable to any wireless communication system that uses a directional beam.

[0107] (Modification 2 common to the first to third embodiments) In each embodiment, a communication control unit 14 is provided on the terminal device side and a configuration in which it causes each wireless communication unit 12 to perform a scan operation has been described. However, the communication control unit 14 may also be located on the base station device side or on its higher-level network for control. A configuration in which the base station device has multiple wireless communication units 12 and causes each wireless communication unit 12 to perform a scan operation is also included in the present invention.

[0108] (Modification 3 common to the first to third embodiments) In each embodiment, the weight coefficients were described using a fixed table as an example, but the weight coefficients may be dynamically changed in response to changes in communication conditions, surrounding environment, etc.

[0109] (Modification 4 common to the first to third embodiments) In each embodiment, in order to prevent frequent switching of connection destinations, a predetermined threshold may be set for quality information, and when the value indicated by the quality information of the communication link connected to the wireless communication device 20 falls below the predetermined threshold, the device may be configured to execute the process shown in Figure 7, Figure 12, or Figure 17. In this configuration, the wireless communication device 10 in the first embodiment collects quality information with the connected wireless communication device 20 at a predetermined timing, and executes the process shown in Figure 7 when the collected quality information falls below a predetermined threshold. The wireless communication device 10 in the second embodiment collects quality information with the connected wireless communication device 20 at a predetermined timing, and executes the process shown in Figure 12 when the collected quality information falls below a predetermined threshold. The wireless communication device 10a in the third embodiment collects quality information with the connected wireless communication device 20 at a predetermined timing, and executes the process shown in Figure 17 when the collected quality information falls below a predetermined threshold.

[0110] (Modification 5 common to the first to third embodiments) In each embodiment, the acquisition of quality information and the control of scanning the surrounding environment were shown as being performed by a loop asynchronous to the communication link connection process, but the loop may also be controlled to start when the communication link connection process is triggered.

[0111] (Modification 6 common to the first to third embodiments) Quality information may be acquired periodically, or it may be acquired at any time based on external control, etc.

[0112] (Modification 7 common to the first to third embodiments) Quality information is expected to fluctuate over time. Therefore, the wireless communication devices 10 and 10a in each embodiment may collect multiple pieces of quality information and use the statistical value (for example, the average value) of the collected multiple pieces of quality information as the quality information for the process shown in Figure 7, Figure 12, or Figure 17.

[0113] (Modification 8 common to the first to third embodiments) In each embodiment, the explanation was given using a base station device installed on the ground and a terminal device having one or more wireless communication units 12 installed on a robotic trolley as examples. However, the present invention is not limited to such scenarios and can be applied to wireless communication devices having one or more wireless communication units 12 installed on a vehicle, or to any wireless communication device such as a smartphone.

[0114] (Modification 9 common to the first to third embodiments) In each embodiment, a configuration was shown in which a weighting coefficient was multiplied by the value shown as quality information as weighting for quality information. In contrast, the weighting for quality information may be done by adding or subtracting a weighting coefficient from the value shown as quality information.

[0115] In each of the embodiments described above, some or all of the functional units of the wireless communication devices 10, 10a (for example, the wireless communication unit 12, the surrounding environment information collection units 13, 13a, and the communication control units 14, 14a) are implemented as software by one or more processors such as a CPU (Central Processing Unit) executing a program stored in a storage device and memory having a non-volatile recording medium (non-temporary recording medium). The program may be recorded on a computer-readable non-temporary recording medium. A computer-readable non-temporary recording medium is, for example, a portable medium such as a flexible disk, magneto-optical disk, ROM (Read Only Memory), CD-ROM (Compact Disc-ROM), or a storage device such as a hard disk built into a computer system.

[0116] Some or all of the functional parts of the wireless communication devices 10, 10a may be implemented using hardware including electronic circuits (or circuits) such as LSI (Large Scale Integrated Circuit), ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), or FPGA (Field Programmable Gate Array).

[0117] While embodiments of this invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and includes designs and the like that do not depart from the spirit of this invention.

[0118] This invention can be applied to wireless communication devices that communicate wirelessly with one or more other wireless communication devices.

[0119] 10, 10a, 20... Wireless communication device, 11... Data processing unit, 12, 12-1, 12-2... Wireless communication unit, 13, 13a... Surrounding environment information collection unit, 14, 14a... Communication control unit, 15, 15-1, 15-2... Antenna

Claims

1. A wireless communication device comprising: a surrounding environment information collection unit that collects quality information representing the quality of wireless communication for each combination of a wireless communication device located in the vicinity and each of the candidate beams that can be formed; a communication control unit that weights the quality information collected by the surrounding environment information collection unit using a weighting coefficient that makes it easier to select a candidate beam closer to the center among the candidate beams that can be formed, and selects a wireless communication device to communicate with based on the weighted quality information; and a wireless communication unit that wirelessly connects with the selected wireless communication device to communicate with.

2. A wireless communication system comprising a first communication device and one or more second communication devices that communicate with the first communication device, wherein the first communication device comprises: a peripheral environment information collection unit that collects quality information representing the quality of wireless communication for each combination of the one or more second communication devices located in the vicinity and each of the candidate beams that can be formed; a communication control unit that weights the quality information collected by the peripheral environment information collection unit using a weighting coefficient that makes it easier to select a candidate beam closer to the center among the candidate beams that can be formed, and selects a second wireless communication device to communicate with based on the weighted quality information; and a wireless communication unit that wirelessly connects with the selected second wireless communication device to communicate with, wherein the one or more second communication devices communicate with the first communication device.

3. A wireless communication method comprising: collecting quality information representing the quality of wireless communication for each combination of a wireless communication device located in the vicinity and each of the possible candidate beams; weighting the collected quality information using a weighting coefficient that makes it easier to select a candidate beam closer to the center from among the possible candidate beams; selecting a wireless communication device to communicate with based on the weighted quality information; and establishing a wireless connection with the selected wireless communication device.

4. A computer program for causing a computer to perform the following steps: a surrounding environment information collection step of collecting quality information representing the quality of wireless communication for each combination of a wireless communication device located in the vicinity and each candidate beam that can be formed; a communication control step of weighting the quality information collected in the surrounding environment information collection step using a weighting coefficient that makes it easier to select a candidate beam closer to the center from among the candidate beams that can be formed, and selecting a wireless communication device to communicate with based on the weighted quality information; and a wireless communication step of wirelessly connecting with the selected wireless communication device to communicate with.

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