Wireless communication system, terminal station equipment, wireless communication method and program

Abstract

This wireless communication system includes a plurality of base station devices and a terminal station device. The terminal station device includes: a first wireless communication unit that is connected to a first base station device among the plurality of base station devices present in the periphery of the terminal station device; a control unit that records information about the first base station device in a storage unit as destination information and selects a second base station device according to, among a plurality of communication quality indicators of the base station devices, a communication quality indicator of a second base station device different from the first base station device; and a second wireless communication unit that is connected to the selected second base station device.

Description

Technical Field

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

Background Art

[0002] In wireless communication using a high-frequency band such as the millimeter-wave band, it is possible to secure a wider bandwidth compared to wireless communication using the microwave band. As a wireless communication method using a high-frequency band, for example, there is IEEE802.11ad. Wireless communication using a high-frequency band has advantages such as high directivity of wireless signals in the propagation path and less interference with other wireless communications. For this reason, studies are being advanced toward the spread of wireless communication using a high-frequency band (see Non-Patent Document 1).

[0003] The distance attenuation amount of a wireless signal in the propagation path increases according to the frequency of the wireless signal. Also, wireless signals in wireless communication such as IEEE802.11ad using the 60GHz band are easily absorbed by oxygen in the propagation path. For these reasons, in wireless communication using a high-frequency band such as the millimeter-wave band, a base station device forms a directional beam (beamforming) toward a terminal station device that is a communication partner, and transmits a wireless signal toward the terminal station device. Also, the base station device performs beamforming toward the terminal station device and receives a wireless signal from the terminal station device. Similarly, the terminal station device may also perform beamforming toward the base station device and receive a wireless signal from the base station device. Further, the terminal station device may perform beamforming toward the base station device and transmit a wireless signal toward the base station device (see Non-Patent Document 2).

[0004] Figure 19 shows an example of a communication link in a wireless communication system using millimeter-wave beamforming. When a radio signal is transmitted from a base station 100 to a terminal station 200, the ground-based base station 100 selects a directional beam from among the directional beams that the base station 100 can form that maximizes the received power at the terminal station 200. Similarly, the mobile terminal station 200 also selects a directional beam from among the directional beams that the terminal station 200 can form that maximizes the received power of the radio signal.

[0005] In Figure 19, the base station equipment 100 forms a directional beam 400, and the terminal station equipment 200 forms a directional beam 500. In this way, a communication link 600 is formed using the directional beam 400 and the directional beam 500.

[0006] When wireless communication using millimeter-wave beamforming is applied to a mobile communication system, the base station equipment 100 and the terminal station equipment 200 must adaptively switch the directional beam in response to the movement of the terminal station equipment 200 and surrounding propagation path fluctuations, so that the directional beam can track the movement of the terminal station equipment 200 and the surrounding propagation path fluctuations. In particular, if propagation path fluctuations occur that shield the propagation path used by the communication link 600, the received power of the wireless signal may drop sharply, causing the communication link 600 to be disconnected and communication between the base station equipment 100's higher-level network equipment (not shown) and the terminal station equipment 130 to be interrupted.

[0007] Therefore, in order to avoid communication interruptions, multiple wireless communication units 300 may be provided in the terminal station equipment 200. By connecting the multiple wireless communication units 300 to different base station equipment 100, it is possible to achieve redundancy in the communication link.

[0008] Figure 20 shows an example of a redundant communication link. The terminal station device 130 has two wireless communication units. In Figure 20, the two wireless communication units are wireless communication unit 140 and wireless communication unit 150. Wireless communication unit 140 forms a communication link 160 with the base station device 110. Wireless communication unit 150 forms a communication link 170 with the base station device 120. For example, even if an obstruction enters the propagation path of the wireless signal of communication link 160 and communication link 160 is interrupted, communication link 170 is maintained. Therefore, the connection between the base station device 120's higher-level network device (not shown) and the terminal station device 130 is maintained.

[0009] However, when such redundant communication link configurations are applied to autonomous distributed wireless communication systems like "IEEE802.11ad," the benefits of redundancy may not be fully realized. In autonomous distributed wireless communication systems, each wireless communication unit independently controls its connection based on communication quality indicators such as RSSI (Received Signal Strength Indicator) measured by each unit. If there is a bias in the RSSI of each base station device (for example, if terminal station devices are located near the same base station device), the benefits of redundancy may not be fully realized because multiple wireless communication units are connected to the same base station device.

[0010] Figure 21 shows an example of a communication link in a wireless communication system when a terminal station device 130 is located near a base station device 110. In Figure 21, the RSSI measured by the wireless communication unit 140 with respect to the base station device 110 is higher than the RSSI measured by the wireless communication unit 140 with respect to the base station device 120. Similarly, the RSSI measured by the wireless communication unit 150 with respect to the base station device 110 is higher than the RSSI measured by the wireless communication unit 150 with respect to the base station device 120.

[0011] Therefore, both the wireless communication unit 140 and the wireless communication unit 150 are connected to the base station device 110. In this case, the communication link 180 formed between the base station device 110 and the wireless communication unit 150 is close to the communication link 160 formed between the base station device 110 and the wireless communication unit 140. In such a case, there is a high possibility that both communication links 160 and 180 will be simultaneously shielded, resulting in a communication interruption and a disruption of communication between the terminal station device 130 and the higher-level network device (not shown). Thus, conventionally, even if the terminal station device 130 is equipped with multiple wireless communication units to achieve a redundant communication link configuration, the effect of redundancy may not be fully obtained.

[0012] Conventionally, when terminal station equipment equipped with multiple wireless communication units supporting the same communication standard performs connection control, multiple wireless communication units may end up connecting to the same base station equipment. In this case, since multiple communication links that are close to each other are susceptible to the same obstacles, it may not be possible to improve the stability of communication.

[0013] Furthermore, if the terminal station equipment can connect to multiple base station equipment using multiple wireless communication units provided in the terminal station equipment, the terminal station equipment may connect not only to the first base station equipment but also to the second base station equipment (see Non-Patent Document 3). By making the communication links redundant in this way, the risk of multiple communication links between the same base station equipment and terminal station equipment being simultaneously blocked is reduced, thereby improving the stability of communication. [Prior art documents] [Non-patent literature]

[0014] [Non-Patent Document 1] Takinami et al., "Standardization Trends and Elemental Technologies of Millimeter-Wave Wireless LAN Systems," IEICE Communications Society Magazine, Autumn 2016, No. 38, pp. 100-106. [Non-Patent Document 2] 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), 2012 / 12 / 28 [Non-Patent Document 3] Iwakuni et al., “60GHz Band Wireless LAN Transmission Experiment in Ultra-High-Speed ​​Vehicle Driving Environment”, B-5-40, 2022 IEICE General Conference [Overview of the project] [Problems that the invention aims to solve]

[0015] However, even if the communication link is made redundant by connecting the terminal station equipment to the first and second base station equipment, the communication quality between the terminal station equipment and the second base station equipment may be worse than the communication quality between the terminal station equipment and the first base station equipment. For example, if the terminal station equipment moves away from the second base station equipment, the communication quality between the second base station equipment and the terminal station equipment may deteriorate. In this way, it may not be possible to improve the stability of communication.

[0016] In view of the above circumstances, the present invention aims to provide a wireless communication system, terminal station equipment, wireless communication method, and program that can improve the stability of communication. [Means for solving the problem]

[0017] One aspect of the present invention is a wireless communication system comprising a plurality of base station devices and a terminal station device, wherein the terminal station device includes a first wireless communication unit connected to a first base station device among the plurality of base station devices in the vicinity, a control unit that records information relating to the first base station device as connection destination information in a storage unit and selects the second base station device based on a communication quality index of a second base station device different from that of the first base station device among a plurality of communication quality indices of the plurality of base station devices, and a second wireless communication unit connected to the selected second base station device.

[0018] One aspect of the present invention is a wireless communication system comprising a plurality of base station devices and a terminal station device, wherein the terminal station device includes a first wireless communication unit that connects to a first connection destination which is a first base station device among the plurality of base station devices in the vicinity, a second wireless communication unit that connects to a second connection destination which is either the first base station device or a second base station device among the plurality of base station devices, and a control unit that determines whether the first connection destination and the second connection destination are the same, and if it is determined that the first connection destination and the second connection destination are the same, changes the second connection destination to the second base station device based on a communication quality index of the second base station device that is different from that of the first base station device among a plurality of communication quality indexes of the plurality of base station devices.

[0019] One aspect of the present invention is a terminal station device comprising: a first wireless communication unit connected to a first base station device among a plurality of base station devices in the vicinity; a control unit that records information relating to the first base station device as connection destination information in a storage unit, and selects the second base station device based on a communication quality index of a second base station device that is different from that of the first base station device among a plurality of communication quality indexes of the plurality of base station devices; and a second wireless communication unit connected to the selected second base station device.

[0020] One aspect of the present invention is a terminal station device comprising: a first wireless communication unit that connects to a first connection destination which is a first base station device among a plurality of base station devices in the vicinity; a second wireless communication unit that connects to a second connection destination which is either the first base station device or a second base station device among the plurality of base station devices; and a control unit that determines whether the first connection destination and the second connection destination are the same, and if it is determined that the first connection destination and the second connection destination are the same, changes the second connection destination to the second base station device based on a communication quality index of the second base station device that is different from that of the first base station device among a plurality of communication quality indexes of the plurality of base station devices.

[0021] One aspect of the present invention is a wireless communication method performed by a terminal station device, comprising: a first wireless communication step of connecting to a first base station device among a plurality of base station devices in the vicinity; a control step of recording information relating to the first base station device as connection destination information in a storage unit, and selecting a second base station device based on a communication quality index of a second base station device that is different from the first base station device among a plurality of communication quality indices of the plurality of base station devices; and a second wireless communication step of connecting to the selected second base station device.

[0022] One aspect of the present invention is a wireless communication method performed by a terminal station device, comprising: a first wireless communication step of connecting to a first destination which is a first base station device among a plurality of base station devices in the vicinity; a second wireless communication step of connecting to a second destination which is either the first base station device or a second base station device among the plurality of base station devices; and a control step of determining whether the first destination and the second destination are the same, and if it is determined that the first destination and the second destination are the same, changing the second destination to the second base station device based on a communication quality index of the second base station device that is different from that of the first base station device among a plurality of communication quality indices of the plurality of base station devices.

[0023] One aspect of the present invention is a program for causing a computer to execute a first wireless communication procedure for connecting to a first base station device among a plurality of base station devices existing in the surroundings, record information regarding the first base station device in a storage unit as connection destination information, and select a second base station device different from the first base station device based on a communication quality index of the second base station device among a plurality of communication quality indexes of the plurality of base station devices, and execute a second wireless communication procedure for connecting to the selected second base station device.

[0024] One aspect of the present invention is a program for causing a computer to execute a first wireless communication procedure for connecting to a first connection destination which is a first base station device among a plurality of base station devices existing in the surroundings, a second wireless communication procedure for connecting to a second connection destination which is the first base station device or a second base station device among the plurality of base station devices, determine whether the first connection destination and the second connection destination are the same, and if it is determined that the first connection destination and the second connection destination are the same, execute a control procedure for changing the second connection destination to the second base station device based on a communication quality index of the second base station device different from the first base station device among a plurality of communication quality indexes of the plurality of base station devices.

Advantages of the Invention

[0025] According to the present invention, it is possible to improve the stability of communication.

Brief Description of the Drawings

[0026] [Figure 1] It is a diagram showing a configuration example of a wireless communication system in the first embodiment. [Figure 2] It is a diagram showing a first example of a state management table in the first embodiment. [Figure 3] It is a flowchart showing an operation example of a control unit at the time of signal acquisition in the first embodiment. [Figure 4] It is a diagram showing a second example of a state management table in the first embodiment. [Figure 5]This figure shows a third example of the state management table in the first embodiment. [Figure 6] This figure shows a fourth example of the state management table in the first embodiment. [Figure 7] This figure shows a fifth example of the state management table in the first embodiment. [Figure 8] This flowchart shows an example of the operation of the wireless communication unit during communication connection in the first embodiment. [Figure 9] This flowchart shows an example of the operation of the wireless communication unit when communication is interrupted in the first embodiment. [Figure 10] This figure shows a sixth example of the state management table in the first embodiment. [Figure 11] This figure shows a first example of a state management table in the second embodiment. [Figure 12] This flowchart shows an example of the operation of the control unit during signal acquisition in the second embodiment. [Figure 13] This figure shows a second example of a state management table in the second embodiment. [Figure 14] This flowchart shows an example of the operation of the control unit when checking the state management table in the second embodiment. [Figure 15] This figure shows a third example of the state management table in the second embodiment. [Figure 16] This flowchart shows an example of the operation of the wireless communication unit during communication connection in the second embodiment. [Figure 17] This flowchart shows an example of the operation of the wireless communication unit when the connection destination is changed in the second embodiment. [Figure 18] This figure shows an example of the hardware configuration of the terminal station equipment in each embodiment. [Figure 19] This figure shows an example of a communication link in a wireless communication system that uses millimeter-wave beamforming. [Figure 20] This figure shows an example of a redundant communication link. [Figure 21]This diagram shows an example of a communication link in a wireless communication system when a terminal station is located near a base station. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described in detail with reference to the drawings. (First Embodiment) Figure 1 shows an example configuration of the wireless communication system 1 in the first embodiment. The wireless communication system 1 is a system that performs wireless communication. The wireless communication system 1 comprises a terminal station device 2 and a plurality of base station devices 3.

[0028] The terminal station device 2 comprises a control unit 20 and a plurality of wireless communication units 21. In Figure 1, the plurality of wireless communication units 21 are, for example, wireless communication unit 21-1 and wireless communication unit 21-2. Hereafter, some of the symbols common to each wireless communication unit 21 will be omitted, and the wireless communication unit will be referred to as "wireless communication unit 21". The terminal station device 2 is, for example, an information processing terminal such as a smartphone terminal or a tablet terminal. The terminal station device 2 performs wireless communication with the base station device 3.

[0029] In Figure 1, the multiple base station devices 3 are, for example, base station device 3-1 and base station device 3-2. Hereafter, some of the symbols common to each base station device 3 will be omitted, and the base station device will be referred to as "base station device 3". Base station device 3 is equipped with an antenna. Base station device 3 performs wireless communication with terminal station device 2 using the antenna. Base station device 3 communicates with a higher-level network device (not shown).

[0030] Next, the control unit 20 will be described. The control unit 20 is a functional unit that controls the operation of multiple wireless communication units 21. The control unit 20 stores a state management table. The state management table is a data table for managing the communication status of each of the multiple wireless communication units 21. The control unit 20 selects the base station device 3 to which each of the multiple wireless communication units 21 will connect, according to the communication status of each of the multiple wireless communication units 21.

[0031] Figure 2 shows a first example of a state management table in the first embodiment. In Figure 2, in the state management table, source information, status, and destination information are associated with each other. Source information represents either the wireless communication unit 21-1 or the wireless communication unit 21-2. Status represents the communication status of the wireless communication unit 21 and the communication status of the base station device 3. Communication status is expressed as not connected, connection in progress, or connected. Destination information is information about the base station device 3 that is the destination, and represents, for example, the identifier of base station device 3-1 or the identifier of base station device 3-2.

[0032] Furthermore, as information regarding the base station device 3, any information (identifier) ​​that can identify the base station device 3 in any communication standard that the base station device 3 supports can be used. For example, the information regarding the base station device 3 may be an identifier used to identify a logical cell in a higher layer. For example, if the communication standard is "IEEE802.11ad", the information regarding the base station device 3 may be expressed using BSSID (Basic Service Set Identifier). For example, if the communication standard is 5G (5th Generation) standardized by 3GPP (registered trademark) (3rd Generation Partnership Project), the information regarding the base station device 3 may be expressed using PCI (Physical Cell ID).

[0033] In the initial state, the wireless communication unit 21-1 and the wireless communication unit 21-2 are not connected to either base station device 3. To match the communication status in the initial state, the status management table shown in Figure 2 records that the status of wireless communication unit 21-1 is unconnected and the status of wireless communication unit 21-2 is unconnected.

[0034] Each wireless communication unit 21, for example, supports the same communication standard. Here, wireless communication unit 21-1 and wireless communication unit 21-2 transmit a signal to the control unit 20 at approximately the same time to confirm the start of connection to the base station device (hereinafter referred to as the "connection start confirmation signal"). However, in reality, due to differences in the component performance of each wireless communication unit 21 and the processing timing conditions of the processor in the terminal station device 2, the connection start confirmation signals do not arrive at the control unit 20 at the same time. Therefore, in the following example, the connection start confirmation signal from wireless communication unit 21-1 arrives at the control unit 20 before the connection start confirmation signal from wireless communication unit 21-2.

[0035] Furthermore, in case the signal transmitted from the wireless communication unit 21-1 and the signal transmitted from the wireless communication unit 21-2 arrive at the control unit 20 at the same time, the control unit 20 may be equipped with a function unit that processes multiple arriving signals sequentially. The control unit 20 may also sequentially instruct the wireless communication unit 21-1 and the wireless communication unit 21-2 to start the connection.

[0036] Figure 3 is a flowchart showing an example of the operation of the control unit when a signal is acquired in the first embodiment. The operation shown in Figure 3 starts when the control unit 20 acquires a signal from the wireless communication unit 21-1. The control unit 20 acquires a signal from the wireless communication unit 21-1. The control unit 20 determines the type of signal acquired (step S101).

[0037] If the acquired signal is determined to be a connection start confirmation signal (step S101: connection start confirmation), the control unit 20 determines whether or not the wireless communication unit 21, which is in the process of connecting, is recorded in the status management table (step S102).

[0038] In the initial state, the status of all wireless communication units recorded in the status management table represents "not connected". If no wireless communication unit 21 currently in the connection process is recorded in the status management table (step S102: NO), the control unit 20 records in the status management table that the status of wireless communication unit 21-1 is in the connection process (step S103).

[0039] Figure 4 shows a second example of the state management table in the first embodiment. The state management table shown in Figure 4 records that the state of the wireless communication unit 21-1 is in connection processing and the state of the wireless communication unit 21-2 is not connected.

[0040] The control unit 20 transmits a connection start permission signal and a list of connection destination information recorded in the status management table to the wireless communication unit 21-1. If no wireless communication unit 21 in a connected state is recorded in the status management table, the control unit 20 transmits a list of empty connection destination information to the wireless communication unit 21-1 (step S104). The control unit 20 then terminates the process shown in Figure 3.

[0041] If the acquired signal is determined to be a signal reporting that the connection to base station device 3-1 has been completed (step S101: connection completion report), the control unit 20 records in the status management table that the status of the wireless communication unit 21-1 is connected and the connection destination information (information indicating that the connection destination is base station device 3-1) (step S105). The control unit 20 then terminates the process shown in Figure 3.

[0042] Figure 5 shows a third example of the state management table in the first embodiment. The state management table shown in Figure 5 records that the wireless communication unit 21-1 is connected to base station device 3-1, and that the state of wireless communication unit 21-2 is not connected.

[0043] If the acquired signal is determined to be a signal reporting that the connection to base station device 3-1 has been disconnected (step S101: disconnection report), the control unit 20 records in the status management table that the status of the wireless communication unit 21-1 is disconnected. Also, if the connection destination of the wireless communication unit 21-1 is recorded in the status management table, the control unit 20 deletes the connection destination information of the wireless communication unit 21-1 from the status management table (step S106). The control unit 20 then terminates the process shown in Figure 3.

[0044] For example, during the time between the execution of step S103 for the wireless communication unit 21-1 and the execution of step S105 for the wireless communication unit 21-1, the status of the wireless communication unit 21-1 is recorded in the status management table as being in connection processing. When the status management table records that the wireless communication unit 21 is in connection processing (step S102: YES), the control unit 20 sends a standby instruction to the wireless communication unit 21-2 (step S107). The control unit 20 then terminates the process shown in Figure 3.

[0045] After the operation in step S105 is performed for the wireless communication unit 21-1, the state management table does not record the wireless communication unit 21-1 in the connection processing state (step S102: NO), so the control unit 20 can perform the operation in step S103 for the wireless communication unit 21-2.

[0046] Figure 6 shows a fourth example of the state management table in the first embodiment. The state management table shown in Figure 6 records that the wireless communication unit 21-1 is connected to base station device 3-1 and that the state of the wireless communication unit 21-2 is in the process of connecting.

[0047] The control unit 20 transmits a connection start permission signal and a list of connection destination information in the status management table (information regarding base station device 3-1, which is the connection destination of the wireless communication unit 21-1) to the wireless communication unit 21-2 (step S104). The control unit 20 then completes the process shown in Figure 3.

[0048] If the acquired signal is a signal reporting that the connection to base station device 3-2 has been completed (step S102: connection completion report), the control unit 20 records in the status management table that the status of the wireless communication unit 21-2 is connected and the connection destination information (information indicating that the connection destination is base station device 3-2) (step S105). The control unit 20 then terminates the process shown in Figure 3.

[0049] Figure 7 shows a fifth example of the state management table in the first embodiment. The state management table shown in Figure 7 records that the wireless communication unit 21-1 is connected to base station device 3-1, and the wireless communication unit 21-2 is connected to base station device 3-2.

[0050] If the acquired signal is a signal indicating that the connection to base station device 3-2 has been disconnected (step S102: disconnection report), the control unit 20 records in the status management table that the status of the wireless communication unit 21-2 is disconnected. Also, if the connection destination of the wireless communication unit 21-2 is recorded in the status management table, the control unit 20 deletes the connection destination information of the wireless communication unit 21-2 from the status management table (step S106). The control unit 20 then terminates the process shown in Figure 3.

[0051] Next, the wireless communication unit 21 will be described. Figure 8 is a flowchart illustrating an example of the operation of the wireless communication unit 21 during communication connection in the first embodiment. When the terminal station device 2 is powered on, or when a signal corresponding to user operation is input to the terminal station device 2, the operation shown in Figure 8 begins. Wireless communication units 21-1 and 21-2 receive a signal from the control unit 20 to instruct the start of connection processing based on the same communication standard (hereinafter referred to as the "connection start instruction signal").

[0052] The wireless communication unit 21-1 transmits a connection start confirmation signal to the control unit 20. Similarly, the wireless communication unit 21-2 transmits a connection start confirmation signal to the control unit 20 (step S201).

[0053] The wireless communication unit 21 determines whether it has obtained a signal to authorize the start of a connection (hereinafter referred to as the "connection start authorization signal") and a list of connection destination information from the control unit 20 (step S202). If it is determined that the connection start authorization signal has not been obtained (step S202: NO), the wireless communication unit 21 returns to step S201.

[0054] If the wireless communication unit 21-1 obtains a connection start permission signal (step S202: YES), the wireless communication unit 21-1 determines whether the list of acquired connection destination information is empty (step S203). If the list of acquired connection destination information is empty (step S203: YES), the wireless communication unit 21-1 connects to the base station device 3 based on the connection procedure specified in the communication standard. For example, if the communication quality index (e.g., RSSI) of the base station device 3-1 located near the terminal station device 2 is the best, the wireless communication unit 21-1 connects to the base station device 3-1 (step S208).

[0055] If the list of acquired destination information is not empty (step S203: NO), the wireless communication unit 21-1 measures the communication quality index for base station equipment 3 that is not recorded in the list of destination information for a specified period of time.

[0056] The wireless communication unit 21-1 measures the communication quality index using any method specified in the communication standard. For example, if the communication standard is "IEEE802.11ad", the wireless communication unit 21-1 may measure the communication quality index using the RSSI of the beacon signal transmitted from the base station device 3.

[0057] Furthermore, by utilizing position measurement techniques that use radio communication signals to measure the position of the opposing radio device (Reference 1: Iwakuni et al., “Experimental Evaluation of Handover Control Using Distancing Function in High-Frequency Band Radio Communication Systems”, B-5-56, 2020 IEICE Society Conference), the radio communication unit 21-1 may use the measurement results of the distance or relative positional relationship with the base station device 3 as a communication quality index. The specified period may be the number of times the RSSI of the periodically transmitted beacon signal is acquired or the measurement time (step S204).

[0058] The wireless communication unit 21-1 derives the slope value of the measured values ​​of multiple communication quality indicators for multiple base station devices 3 that have been acquired. The wireless communication unit 21-1 derives the slope value, for example, based on the result of linear regression on the measured values ​​of the communication quality indicators. The magnitude of the derived slope value is used as a predicted value for the rate of change of the time-series wireless communication quality. That is, if the slope value derived based on the result of linear regression is the largest, it is expected that the received power will increase most rapidly in such a base station device 3. For this reason, by selecting the base station device 3 with the largest slope value of the measured values ​​of the communication quality indicators as the connection destination, an improvement in wireless communication quality can be expected.

[0059] Furthermore, if the distance between the wireless communication unit 21-1 and the base station device 3 is used as a communication quality index, the wireless communication unit 21-1 selects the base station device 3 with the smallest negative slope value of the measured value of the communication quality index (the base station device 3 where the distance decreases rapidly) as the connection destination. This allows the wireless communication unit 21-1 to select the base station device 3 that is expected to provide the best communication quality the fastest, thus improving wireless communication quality. For this reason, the wireless communication unit 21-1 performs the connection process to the base station device 3 that is expected to provide the best communication quality based on multiple wireless communication indexes (step S205).

[0060] The wireless communication unit 21-1 determines whether the connection was successful (step S206). If the connection is successful (step S206: YES), the wireless communication unit 21-1 transmits a connection completion report signal and information about the base station device 3-1, which is the connection destination, to the control unit 20 (step S207). The wireless communication unit 21 then completes the process shown in Figure 8.

[0061] If the connection fails for reasons such as the absence of a base station device 3 near the wireless communication unit 21 (step S206: NO), the system attempts to connect to a predetermined base station device 3 recorded in the acquired list of connection destination information (step S209).

[0062] The wireless communication unit 21-1 determines whether the connection was successful or not (step S210). If the connection is successful (step S210: YES), the wireless communication unit 21-1 returns to step S207.

[0063] If the connection fails (step S210: NO), the wireless communication unit 21-1 transmits a signal (disconnection report signal) to the control unit 20 to report that the connection to the base station device 3-1 has been disconnected (step S211). The wireless communication unit 21 then terminates the process shown in Figure 8.

[0064] Upon receiving the standby instruction, the wireless communication unit 21-2 retransmits a connection start confirmation signal to the control unit 20 (step S201).

[0065] If the wireless communication unit 21-2 determines that it has obtained a connection start permission signal (step S202: YES), the wireless communication unit 21-2 performs a connection process for base station devices 3 that are not recorded in the list of connection destination information (base station devices 3 other than those recorded in the list of connection destination information) based on the list of connection destination information obtained (steps S203, S204, S205).

[0066] The wireless communication unit 21-2 determines whether the connection was successful (step S206). For example, if the wireless communication unit 21-2 obtains a list of connection destination information in which information about base station device 3-1 is recorded, the wireless communication unit 21-2 connects to a base station device 3 other than base station device 3-1 based on the connection procedure specified in the communication standard. For example, if the communication quality index (e.g., RSSI) of base station device 3-2, which is located next to the terminal station device 2 after base station device 3-1, is the second best, the wireless communication unit 21-2 connects to base station device 3-2.

[0067] If the connection is successful (step S206: YES), the wireless communication unit 21-2 transmits a connection completion report signal and information about the base station device 3-2 to the control unit 20 (step S207). The wireless communication unit 21 then completes the process shown in Figure 8.

[0068] If the connection fails for reasons such as the absence of a base station device 3-2 near the wireless communication unit 21 and the presence of a base station device 3-1 near the wireless communication unit 21 (step S206: NO), the wireless communication unit 21-2 attempts to connect to a predetermined base station device 3, including the base station device 3 recorded in the acquired list of connection destination information (step S209).

[0069] The wireless communication unit 21-2 determines whether the connection was successful or not (step S210). If the connection is successful for reasons such as the presence of the base station device 3-1 near the wireless communication unit 21-2 (step S210: YES), the wireless communication unit 21-1 returns to step S207.

[0070] If the connection fails for reasons such as the absence of a base station device 3-1 near the wireless communication unit 21-2 (step S210: NO), the wireless communication unit 21-2 transmits a disconnection report signal to the control unit 20 (step S211). The wireless communication unit 21 then terminates the process shown in Figure 8.

[0071] Thus, instead of both the wireless communication unit 21-1 and the wireless communication unit 21-2 being connected to base station device 3-1 which is close to both units, it is possible for the wireless communication unit 21-2 to be connected to base station device 3-2, which is a base station device other than base station device 3-1. Since the communication link formed by the wireless communication unit 21-1 and the communication link formed by the wireless communication unit 21-2 are separated from each other, resistance to shielding and the like is improved.

[0072] Furthermore, it is necessary to prevent unnecessary information about the base station device 3 from being continuously recorded in the state management table stored in the control unit 20. For this reason, if the communication link is disconnected due to user operation or shielding of the wireless signal propagation path, the wireless communication unit 21 reports to the control unit 20 that the communication link has been disconnected.

[0073] Figure 9 is a flowchart showing an example of the operation of the wireless communication unit when communication is disconnected in the first embodiment. In Figure 9, as an example, the wireless communication unit 21-1 starts the process of disconnecting the communication link between the wireless communication unit 21-1 and the base station device 3-1. The wireless communication unit 21-1 performs a disconnection process on the base station device 3-1, which is the connection destination, based on the connection procedure defined in the communication standard (step S301). After the disconnection process is completed, the wireless communication unit 21-1 transmits a disconnection report signal to the control unit 20 (step S302). The wireless communication unit 21-1 then terminates the process shown in Figure 9.

[0074] In the flowchart shown in Figure 3, if the acquired signal is a signal reporting that the connection to base station device 3-1 has been disconnected (step S102: disconnection report), the control unit 20 records in the status management table that the status of the wireless communication unit 21-1 is disconnected. Also, if the connection destination of the wireless communication unit 21-1 is recorded in the status management table, the control unit 20 deletes the connection destination information of the wireless communication unit 21-1 from the status management table (step S106). The control unit 20 then terminates the process shown in Figure 3.

[0075] Figure 10 shows a sixth example of the state management table in the first embodiment. The state management table shown in Figure 10 records that the state of the wireless communication unit 21-1 is disconnected and the connection destination of the wireless communication unit 21-2 is the base station device 3-2.

[0076] As described above, the wireless communication unit 21-1 connects to base station device 3-1 among the multiple base station devices 3 in the surrounding area. The control unit 20 records information about base station device 3-1 in the storage unit as connection destination information for the wireless communication unit 21-1. The control unit 20 selects, for example, a base station device 3-2 whose communication quality index is improved, based on the communication quality index of a base station device 3-2 that is different from that of base station device 3-1, among the multiple communication quality indices of the multiple base station devices 3. The control unit 20 may also select, for example, a base station device 3-2 whose communication quality index is above a threshold. The wireless communication unit 21-2 connects to the selected base station device 3-2.

[0077] In this way, the wireless communication unit 21-2 connects to a different base station device 3-2 than the base station device 3-1, based on the connection destination information of the wireless communication unit 21-1 in the status management table. As a result, the wireless communication unit 21-2 does not connect to the base station device 3-1 to which the wireless communication unit 21-1 is connected, thus making the communication link redundant and improving the stability of communication.

[0078] Based on a predetermined procedure for predicting fluctuating wireless communication quality, changes in communication quality indicators are predicted (e.g., linear prediction). The wireless communication unit 21 selects the base station equipment 3, antenna, and beam that best improves wireless communication quality (the slope of the measured value of wireless communication quality with respect to the time axis). This makes it possible to obtain diversity effects even in communication systems with rapidly changing wireless communication quality (e.g., high-frequency band wireless communication systems).

[0079] By preventing multiple wireless communication units 21 from connecting to the same base station device 3, communication stability can be improved as a result of the redundancy of the communication links. By preventing communication links from being too close together and distributing the propagation paths, communication links are made redundant, which can improve the stability of communication between the base station device 3's higher-level network device (not shown) and the terminal station device 2. Furthermore, by having multiple wireless communication units 21 that conform to the same communication standard in the terminal station device 2, the communication links of the terminal station device 2 become redundant, which can reduce the possibility of multiple communication links failing simultaneously.

[0080] (Second Embodiment) In the second embodiment, after each wireless communication unit 21 has completed its connection to the base station device 3, the control unit 20 changes the selection of the base station device 3 to which the wireless communication unit 21 is connected in accordance with changes in the wireless communication quality of the base station device 3 to which it is connected. This difference from the first embodiment will be mainly explained in the second embodiment.

[0081] Figure 11 shows a first example of the state management table in the second embodiment. In the state management table in the second embodiment, source information and destination information are associated with each other. In the initial state, the wireless communication unit 21-1 and the wireless communication unit 21-2 are not connected to either base station device 3. To match the communication state in the initial state, the state management table shown in Figure 11 records that the state of wireless communication unit 21-1 is unconnected and the state of wireless communication unit 21-2 is unconnected.

[0082] After each wireless communication unit 21 is connected to the base station device 3, the control unit 20 changes the selection of the base station device 3 to which the wireless communication unit 21 will connect. This change causes, for example, two wireless communication units 21-1 to connect to base station device 3-1 located closer to terminal station device 2-1, and wireless communication unit 21-2 to connect to base station device 3-2 located further away from terminal station device 2-2.

[0083] Figure 12 is a flowchart showing an example of the operation of the control unit 20 when acquiring a signal in the second embodiment. The control unit 20 acquires a connection completion report signal or a disconnection report signal from the wireless communication unit 21. The control unit 20 determines the type of signal acquired (step S401).

[0084] If the acquired signal is determined to be a connection completion report signal (step S401: connection completion report), the control unit 20 records information about the base station device 3, which is the connection destination of the wireless communication unit 21 that transmitted the connection completion report signal, in the status management table as connection destination information for the wireless communication unit 21 that transmitted the connection completion report signal (step S402). The control unit 20 then terminates the process shown in Figure 12.

[0085] Figure 13 shows a second example of the state management table in the second embodiment. For example, the wireless communication unit 21-1 and the wireless communication unit 21-2 are simultaneously connected to a base station device 3-1 located close to the terminal station device 2. Therefore, the state management table shown in Figure 13 records that the connection destination of the wireless communication unit 21-1 is the base station device 3-1, and the connection destination of the wireless communication unit 21-2 is the base station device 3-1.

[0086] If the acquired signal is determined to be a signal reporting that the connection to the base station device 3 has been disconnected (step S401: disconnection report), the control unit 20 records in the status management table that the status of the wireless communication unit 21 that sent the disconnection report signal is disconnected. Also, if the connection destination of the wireless communication unit 21 that sent the disconnection report signal is recorded in the status management table, the control unit 20 deletes the connection destination information of the wireless communication unit 21 that sent the disconnection report signal from the status management table (step S403). The control unit 20 then terminates the process shown in Figure 3.

[0087] In a situation where both the wireless communication unit 21-1 and the wireless communication unit 21-2 are simultaneously connected to the base station device 3-1, which is located close to the terminal station device 2, if an obstruction is placed between the terminal station device 2 and the base station device 3-1, there is a high probability that multiple communication links between the two wireless communication units 21 and the base station device 3-1 will be simultaneously lost.

[0088] Therefore, in order to reduce the possibility of multiple communication links being simultaneously interrupted, in the second embodiment, the control unit 20 transmits instructions to change the selection of the connection destination to one or more wireless communication units 21 as needed. That is, the control unit 20 transmits instructions to change the selection of the connection destination to one or more wireless communication units 21 according to the results of checking the record in the status management table.

[0089] For example, the control unit 20 checks the contents of the status management table at predetermined intervals and sends an instruction to change the selection of the connection destination at predetermined intervals. For example, the control unit 20 may send an instruction to change the selection of the connection destination at predetermined intervals at any timing (for example, the execution timing of step S402 or step S403).

[0090] Figure 14 is a flowchart showing an example of the operation of the control unit 20 when checking the state management table in the second embodiment. The control unit 20 checks the contents of the state management table at a predetermined timing. Here, the control unit 20 resets the counter "i" to 0 (step S501). The control unit 20 then counts up the counter "i" (step S502).

[0091] The control unit 20 determines whether the connection destination information of the wireless communication unit 21-1 associated with the counter "i" after the count-up, and the connection destination information of the wireless communication unit 21 associated with each counter "from 1 to (i-1)" before the count-up, match in the state management table. That is, the control unit 20 determines whether the connection destination information of row i of the state management table matches in the state management table (step S503).

[0092] If step S503 is executed for the first time, it is determined that the connection destination information does not match. If it is determined that the connection destination information does not match (step S503: NO), the control unit 20 determines whether the value of counter "i" matches the number of wireless communication units 21 (step S504).

[0093] If step S504 is executed for the first time, the value of counter "i" ("1") does not match the number of wireless communication units 21 ("2"). In this case, it is determined that the value of counter "i" and the number of wireless communication units 21 do not match.

[0094] If it is determined that the value of counter "i" does not match the number of wireless communication units 21 (step S504: NO), the control unit 20 returns to step 503.

[0095] If step S503 is executed two or more times, the connection destination of wireless communication unit 21-2 and the connection destination of wireless communication unit 21-1 match in the state management table shown in Figure 13.

[0096] If it is determined that the connection destination information matches (step S503: YES), the control unit 20 transmits to the radio communication unit 21 (radio communication unit 21-2) in row i of the status management table information regarding the base station device 3 from row 1 to row (i-1) to which the radio communication unit 21-1 is connected (for example, the identifier of base station device 3-1) and an instruction to change the selection of the connection destination (hereinafter referred to as the "connection destination change instruction") (step S505). The control unit 20 waits to receive a report signal (connection completion report signal or disconnection report signal) transmitted from the radio communication unit 21 in row i of the status management table (step S506).

[0097] The control unit 20 determines whether or not it has acquired a report signal from the radio communication unit 21 (radio communication unit 21-2) in row i of the status management table (step S507). If it is determined that no report signal has been acquired (step S507: NO), the control unit 20 returns to step S505. If it is determined that a report signal has been acquired (step S507: YES), the control unit 20 determines whether the acquired signal is a connection completion report signal or a disconnection report signal (step S508).

[0098] If the signal obtained from the i-th row wireless communication unit 21 (wireless communication unit 21-2) is determined to be a connection completion report signal to the base station device 3-2 (step S508: connection completion report), the control unit 20 records information about the base station device 3-2, which is the connection destination of the wireless communication unit 21-2 that transmitted the connection completion report signal (for example, the identifier of the base station device 3-2), as connection destination information in the status management table (step S509). The control unit 20 returns to step S504.

[0099] In step S504, the value of counter "i" is re-determined to match the number of wireless communication units 21, which is "2". If it is determined that the value of counter "i" matches the number of wireless communication units 21 (step S504: YES), the control unit 20 terminates the process shown in Figure 14.

[0100] Figure 15 shows a third example of the state management table in the second embodiment. The state management table shown in Figure 15 records that the wireless communication unit 21-1 is connected to base station device 3-1, and the wireless communication unit 21-2 is connected to base station device 3-2.

[0101] In this way, instead of both the wireless communication unit 21-1 and the wireless communication unit 21-2 being connected to the base station device 3-1 closest to the terminal station device 2, it is possible to distribute the connection destination by having one of the wireless communication unit 21-1 or the wireless communication unit 21-2 connect to the base station device 3-2. As a result, the communication link formed by the wireless communication unit 21-1 and the communication link formed by the wireless communication unit 21-2 are separated from each other, improving resistance to shielding and other obstacles.

[0102] If the signal obtained from the wireless communication unit 21 is a signal reporting that the connection to the base station device 3 has been disconnected (step S508: disconnection report), the control unit 20 records in the status management table that the status of the wireless communication unit 21 that sent the disconnection report signal is disconnected. Also, if the connection destination of the wireless communication unit 21 that sent the disconnection report signal is recorded in the status management table, the control unit 20 deletes the connection destination information of the wireless communication unit 21 that sent the disconnection report signal from the status management table (step S510). The control unit 20 returns to step S504.

[0103] Figure 16 is a flowchart showing an example of the operation of the wireless communication unit 21 during communication connection in the second embodiment. When the terminal station device 2 is powered on, or when a signal corresponding to user operation is input to the terminal station device 2, the operation shown in Figure 16 begins. Wireless communication units 21-1 and 21-2 receive a connection start instruction signal from the control unit 20.

[0104] The wireless communication unit 21-1 performs connection processing to a predetermined base station device 3 based on the connection procedure specified in the communication standard. Similarly, the wireless communication unit 21-2 performs connection processing to a predetermined base station device 3 based on the connection procedure specified in the communication standard (step S601).

[0105] The wireless communication unit 21 determines whether the connection was successful (step S602). If it is determined that the connection was successful (step S602: YES), the wireless communication unit 21 transmits a connection completion report signal to the control unit 20. The wireless communication unit 21 transmits information about the base station device 3, which is the destination of its wireless communication unit, to the control unit 20 as destination information (step S603). The wireless communication unit 21 then completes the process shown in Figure 16.

[0106] If it is determined that the connection has failed (step S602: NO), the wireless communication unit 21 transmits a disconnection report signal to the control unit 20 (step S604). The wireless communication unit 21 then terminates the process shown in Figure 16.

[0107] Figure 17 is a flowchart showing an example of the operation of the wireless communication unit 21 when the connection destination is changed in the second embodiment. The wireless communication unit 21-2 receives a connection destination change instruction from the control unit 20. The wireless communication unit 21-2 measures a communication quality index for a base station device 3 that is not recorded in the list of connection destination information for a specified period of time.

[0108] The wireless communication unit 21-2 measures the communication quality index using any method specified in the communication standard. For example, if the communication standard is "IEEE802.11ad", the wireless communication unit 21-2 may measure the communication quality index using the RSSI of the beacon signal transmitted from the base station device 3.

[0109] Furthermore, the wireless communication unit 21-2 may use position measurement techniques that utilize wireless communication signals to measure the position of the opposing wireless device (see Reference 1 above) and use the measurement results of the relative distance or relative positional relationship with the base station device 3 as a communication quality index. The specified period may be the number of times the RSSI of the periodically transmitted beacon signal is acquired or the measurement time (step S701).

[0110] The wireless communication unit 21-2 derives the slope value of the measured values ​​of multiple communication quality indicators for multiple base station devices 3 that have been acquired. The wireless communication unit 21-2 derives the slope value, for example, based on the result of linear regression on the measured values ​​of the communication quality indicators. The magnitude of the derived slope value is used as a predicted value for the rate of change of the time-series wireless communication quality. That is, if the slope value derived based on the result of linear regression is the largest, it is expected that the received power will increase most rapidly in such a base station device 3. For this reason, by selecting the base station device 3 with the largest slope value of the measured values ​​of the communication quality indicators as the connection destination, an improvement in wireless communication quality can be expected.

[0111] Furthermore, if the distance between the wireless communication unit 21-2 and the base station device 3 is used as a communication quality index, the wireless communication unit 21-2 selects the base station device 3 with the smallest negative slope value of the measured value of the communication quality index (the base station device 3 whose distance decreases rapidly) as the connection destination. This allows the wireless communication unit 21-2 to select the base station device 3 that is expected to provide the best communication quality the fastest, thus improving wireless communication quality. For this reason, the wireless communication unit 21-2 performs the connection process to the base station device 3 that is expected to provide the best communication quality based on multiple wireless communication indexes (step S702).

[0112] The wireless communication unit 21-2 determines whether the connection was successful (step S703). If the connection is successful (step S703: YES), the wireless communication unit 21-2 transmits a connection completion report signal and information about the base station device 3 to which it is connected to the control unit 20. For example, if the communication quality index of base station device 3-2, which is the next closest to terminal station device 2 after base station device 3-1, is the best, the wireless communication unit 21-2 transmits a connection completion report signal and information about the base station device 3-2 to which it is connected (connection destination information) to the control unit 20 (step S704). The wireless communication unit 21 then completes the process shown in Figure 17.

[0113] If it is determined that the connection has failed for reasons such as the absence of a base station device 3-2 near the wireless communication unit 21 and the presence of a base station device 3-1 near the wireless communication unit 21 (step S703: NO), the wireless communication unit 21-2 attempts to connect to a predetermined base station device 3, including the base station device (base station device 3-1) recorded in the list of acquired connection destination information (step S705).

[0114] The wireless communication unit 21-2 determines whether the connection was successful or not (step S706). If it is determined that the connection to the base station device 3-1 was successful (step S706: YES), the wireless communication unit 21-2 returns to step S703. If it is determined that the connection failed (step S706: NO), the wireless communication unit 21-2 sends a disconnection report signal to the control unit 20 (step S707). The wireless communication unit 21 terminates the process shown in Figure 17.

[0115] It is necessary to prevent unnecessary information about the base station device 3 from being continuously recorded in the state management table stored in the control unit 20. For this reason, when the communication link is disconnected due to user operation or shielding of the radio signal propagation path, the wireless communication unit 21 reports to the control unit 20 that the communication link has been disconnected. Here, the wireless communication unit 21 performs the operations shown in the flowchart in Figure 9. The control unit 20 also performs the operations shown in the flowchart in Figure 12.

[0116] As described above, the wireless communication unit 21-1 connects to a first connection destination, which is base station 3-1 among the multiple base station devices 3 in the surrounding area. The wireless communication unit 21-2 connects to a second connection destination, which is either base station 3-1 or base station 3-2 among the multiple base station devices 3. The control unit 20 determines whether the connection destination of the wireless communication unit 21-1 (first connection destination) and the connection destination of the wireless communication unit 21-2 (second connection destination) are the same. If the control unit 20 determines that the connection destination of the wireless communication unit 21-1 and the connection destination of the wireless communication unit 21-2 are the same, it changes the connection destination of the wireless communication unit 21-2 (second connection destination) to a base station device 3-2 that has an improved communication quality index, for example, among the multiple communication quality indexes of the multiple base station devices 3, based on the communication quality index of base station device 3-2 which is different from that of base station device 3-1. The control unit 20 may also change the connection destination of the wireless communication unit 21-2 to a base station device 3-2 whose communication quality index is above a threshold, for example.

[0117] Thus, if the control unit 20 determines that the connection destination of the wireless communication unit 21-1 and the connection destination of the wireless communication unit 21-2 are the same, it changes the connection destination of the wireless communication unit 21-2 to base station device 3-2. In other words, if multiple wireless communication units 21 are connected to the same base station device 3, the control unit 20 detects that multiple wireless communication units 21 are connected to the same base station device 3 and changes the selection of connection destinations for the wireless communication units 21 so that one or more of the multiple wireless communication units 21 are connected to other base station devices 3. This makes it possible to make the communication link redundant and improve the stability of communication.

[0118] Next, we will explain the common features of each embodiment from the first embodiment to the second embodiment.

[0119] The terminal station device 2 may have three or more wireless communication units 21. The more wireless communication units 21 there are, the more it is possible to connect simultaneously to multiple base station devices 3 at different locations, thereby enabling stable communication with higher-level network devices (not shown) through redundancy.

[0120] The wireless communication unit 21 may be built into the housing of the terminal station device 2, or it may be provided on the outside of the housing of the terminal station device 2. Each wireless communication unit 21 may communicate using a common antenna, or it may communicate using each region that divides the array antenna, or it may communicate using its own antenna.

[0121] The communication standard is not limited to a specific standard such as autonomous distributed or centralized control. The frequency used for communication is not limited to a specific frequency. A terminal station device 2 that supports any communication standard may restrict the connection destination of the base station device 3 based on that communication standard.

[0122] The antenna configuration of the base station device 3 may be a distributed antenna configuration. A distributed antenna configuration is a configuration in which the base station device 3 accommodates multiple antennas located at a distance from the base station device 3. In this case, the same information is transmitted from the multiple antennas located at a distance from the base station device 3 as arbitrary information that can identify the base station device 3.

[0123] Here, terminal station 2 does not have to attempt to connect to a different base station 3 than the one it is already connected to. Terminal station 2 may attempt to connect to a different antenna in the distributed antenna configuration. This provides the benefit of redundancy in the communication link. In this case, base station 3 may embed information that allows it to identify base station 3 and information that allows it to identify the distributed antennas in the signal it transmits to terminal station 2. The radio communication unit 21 may use the information that allows it to identify the distributed antennas in its connection attempts. The radio communication unit 21 may also use the measurement results of the position and direction of base station 3 in its connection attempts. The radio communication unit 21 may also use information that allows it to identify the radio propagation path between the radio communication unit 21 and base station 3 in its connection attempts.

[0124] Furthermore, in each embodiment, as a convenient expression corresponding to the positional relationship between the devices, the equipment of the fixed station is expressed as a base station device, and the equipment of the communication station is expressed as a terminal station device. The role of base station device 3 is not limited to the roles of base station (BS), access point (AP), and initiator in a predetermined communication standard. Similarly, the role of terminal station device 2 is not limited to the roles of user equipment (UE), station (STA), and responder in a predetermined communication standard. Note that terminal station device 2 and base station device 3 may perform the roles (functions) of communication devices defined in a predetermined communication standard. For example, a base station device 3 installed on the ground may perform the function of a station, and a mobile terminal station device 2 may perform the function of an access point.

[0125] Figure 18 shows examples of the hardware configuration of the terminal station device 2 in each embodiment. Some or all of the functional units of the terminal station device 2 are realized as software by a processor 210 such as a CPU (Central Processing Unit) executing a program stored in a storage device 211 having a non-volatile recording medium (non-temporary recording medium) and a memory 212 (storage unit). The program may be recorded on a computer-readable recording medium. A computer-readable recording medium is a non-temporary recording medium such as a portable medium such as a flexible disk, magneto-optical disk, ROM (Read Only Memory), CD-ROM (Compact Disc Read Only Memory), or a storage device such as a hard disk built into a computer system. The communication unit 213 performs wireless communication.

[0126] Some or all of the functional units of the terminal station device 2 may be implemented using hardware including electronic circuits (or circuits) such as LSIs (Large Scale Integration circuits), ASICs (Application Specific Integrated Circuits), PLDs (Programmable Logic Devices), or FPGAs (Field Programmable Gate Arrays).

[0127] Although 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. [Industrial applicability]

[0128] This invention is applicable to communication systems. [Explanation of symbols]

[0129] 1... Wireless communication system, 2... Terminal station equipment, 3... Base station equipment, 20... Control unit, 21... Wireless communication unit, 100... Base station equipment, 110... Base station equipment, 120... Base station equipment, 130... Terminal station equipment, 140... Wireless communication unit, 150... Wireless communication unit, 160... Communication link, 170... Communication link, 180... Communication link, 200... Terminal station equipment, 210... Processor, 211... Memory device, 212... Memory, 213... Communication unit, 300... Wireless communication unit, 400... Directional beam, 500... Directional beam, 600... Communication link

Claims

1. A wireless communication system comprising multiple base station devices and terminal station devices, The aforementioned terminal station equipment, A first wireless communication unit connected to a first base station device among the multiple base station devices located in the surrounding area, A control unit records information relating to the first base station device as connection destination information in a storage unit, and selects the second base station device based on the communication quality indicator of the second base station device that is not recorded as the first base station device in the connection destination information, among the multiple communication quality indicators of the multiple base station devices. It has a second wireless communication unit that connects to the selected second base station device, The control unit selects the second base station device for which the slope value of the linear regression with respect to the measured value of the communication quality index of the second base station device is the largest. Wireless communication system.

2. A first wireless communication unit connected to a first base station device among multiple base station devices in the surrounding area, A control unit records information relating to the first base station device as connection destination information in a storage unit, and selects the second base station device based on the communication quality indicator of the second base station device that is not recorded as the first base station device in the connection destination information, among the multiple communication quality indicators of the multiple base station devices. A second wireless communication unit connected to the selected second base station device, Equipped with, The control unit selects the second base station device for which the slope value of the linear regression with respect to the measured value of the communication quality index of the second base station device is the largest. Terminal station equipment.

3. A wireless communication method performed by terminal station equipment, A first wireless communication step of connecting to a first base station device among multiple base station devices in the surrounding area, A control step of recording information relating to the first base station device as connection destination information in a storage unit, and selecting the second base station device based on the communication quality indicator of the second base station device that is not recorded as the first base station device in the connection destination information, among the multiple communication quality indicators of the multiple base station devices, A second wireless communication step of connecting to the selected second base station device and Includes, The control step includes selecting the second base station device that has the largest slope value of the linear regression of the measured value of the communication quality index of the second base station device. Wireless communication method.

4. On the computer, A first wireless communication procedure for connecting to a first base station device among multiple base station devices in the surrounding area, A control procedure for recording information relating to the first base station device as connection destination information in a storage unit, and selecting the second base station device based on the communication quality indicator of the second base station device that is not recorded as the first base station device in the connection destination information, among the multiple communication quality indicators of the multiple base station devices, A second wireless communication procedure for connecting to the selected second base station device and Make it run, The control procedure includes selecting the second base station device that has the largest slope value of the linear regression of the measured value of the communication quality index of the second base station device. program.

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