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

Abstract

This wireless communication system comprises a wireless terminal and a control unit. The wireless terminal comprises a plurality of wireless modules that wirelessly communicate over different channels with a plurality of respective base stations. The wireless terminal uses one of the plurality of wireless modules as a usage module and stops data transmission from wireless modules other than the usage module. The control unit switches the usage module in the wireless terminal so that the transmission time rate of each of the plurality of wireless modules does not exceed a prescribed upper limit.

Description

Technical Field

[0001] The present invention relates to a technique for controlling a wireless terminal that performs wireless communication by switching a plurality of channels.

Background Art

[0002] A wireless communication system composed of a base station and a wireless terminal is known. As a typical example of a wireless communication system, a public-use wireless LAN (Local Area Network) can be cited. In a public-use wireless LAN, for example, a use case of transmitting data from a base station to a wireless terminal such as a computer terminal or a smartphone terminal is assumed. Furthermore, with the spread of IoT (Internet of Things) terminals in recent years, the number of use cases of transmitting data from the wireless terminal side to the base station has been increasing.

[0003] In relation to wireless communication for IoT, the use of the unlicensed Sub-1GHz band has been institutionalized in various countries (see Non-Patent Document 1 and Non-Patent Document 2). In Japan, the 920 MHz band has been allocated as the frequency band for an electronic tag system. For example, as an active electronic tag system, LPWA (Low Power Wide Area) wireless communication systems such as LoRa (registered trademark) and WiSUN (registered trademark) are known. In addition, the use of IEEE 802.11ah, which is one of the wireless LAN standards, is also being considered.

[0004] Since the number of frequency channels is limited in the 920 MHz band, a case where wireless communication is performed while changing the channels to be used is also conceivable.

[0005] For example, in the country, there is a limit on the total transmission time when using the 920 MHz band, and the total transmission time per hour must be within 360 seconds. Since the wireless communication device restricts data transmission to comply with this total transmission time limit, the throughput is also restricted. However, for the housing of a wireless communication device that switches between and uses two non-overlapping channels, a total transmission time of up to 360 seconds per channel per hour, for a total of 720 seconds, is allowed. Therefore, in order to improve the throughput, it is conceivable to perform wireless communication while changing the channels used by the housing of the wireless communication device.

Prior Art Documents

Non-Patent Documents

[0006]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] Consider the case where a wireless terminal transmits data to a base station. In a situation where there is a transmission time ratio constraint for each channel, it is conceivable to improve the throughput by switching the channels used by the wireless terminal. However, complicated processing is required to switch the used channels within the wireless module provided in the wireless terminal.

[0008] One object of the present invention is to provide a technology capable of simplifying the process of switching the channels used by a wireless terminal.

Means for Solving the Problem

[0009] The first aspect relates to a wireless communication system. The wireless communication system includes a wireless terminal and a control unit. The wireless terminal includes a plurality of wireless modules that perform wireless communication with each of a plurality of base stations on different channels. The wireless terminal uses one of the plurality of wireless modules as a used module and stops data transmission from wireless modules other than the used module. The control unit switches the used module in the wireless terminal so that the transmission time ratio of each of the plurality of wireless modules does not exceed a predetermined upper limit.

[0010] The second aspect relates to a wireless terminal control method for controlling a wireless terminal. The wireless terminal includes a plurality of wireless modules that perform wireless communication with each of a plurality of base stations on different channels. The wireless terminal control method includes a process of selecting one of the plurality of wireless modules as a used module, a process of stopping data transmission from wireless modules other than the used module, a process of switching the used module in the wireless terminal so that the transmission time ratio of each of the plurality of wireless modules does not exceed a predetermined upper limit and includes.

[0011] The third aspect relates to a control device that controls a wireless terminal. The wireless terminal includes a plurality of wireless modules that perform wireless communication with each of a plurality of base stations on different channels. The control device includes one or more processors. The one or more processors perform a process of selecting one of the plurality of wireless modules as a use module, perform a process of stopping data transmission from wireless modules other than the use module, and perform a process of switching the use module in the wireless terminal so that the transmission time ratio of each of the plurality of wireless modules does not exceed a predetermined upper limit. It is configured to execute.

[0012] The fourth aspect relates to a control program executed by a computer. The control program causes the computer to execute the wireless terminal control method according to the second aspect. Alternatively, the control program causes the computer to realize the control device according to the third aspect.

Advantages of the Invention

[0013] According to the present invention, the wireless terminal includes a plurality of wireless modules that perform wireless communication with each of a plurality of base stations on different channels. The control unit switches the use module used by the wireless terminal among the plurality of wireless modules. By switching the use module among the plurality of wireless modules, the channel used for wireless communication can be easily switched. Since there is no need to switch channels within a single wireless module, it is possible to simplify the processing required for channel switching.

Brief Description of the Drawings

[0014]

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Embodiments for Carrying Out the Invention

[0015] Embodiments of the present invention will be described with reference to the accompanying drawings.

[0016] 1. Overview FIG. 1 is a block diagram showing a configuration example of a wireless communication system 1 according to the present embodiment. The wireless communication system 1 includes a wireless terminal 10 and a plurality of base stations 20. The wireless terminal 10 and each base station 20 constitute a wireless communication network and perform wireless communication with each other. For example, the wireless communication system 1 is a wireless LAN system, and the base station 20 is an access point of the wireless LAN. The wireless communication system 1 performs wireless communication using, for example, an unlicensed Sub-1GHz band. For example, the wireless communication system 1 performs wireless communication using the 920 MHz band.

[0017] The wireless terminal 10 can perform wireless communication by switching a plurality of channels (frequency channels). More specifically, the wireless terminal 10 includes a plurality of wireless modules 11 that perform wireless communication on different channels that do not overlap with each other. Each wireless module 11 includes, for example, a network interface controller (network interface card). The plurality of wireless modules 11 are each connected to a plurality of base stations 20 and perform wireless communication with the plurality of base stations 20.

[0018] In the example shown in FIG. 1, the wireless terminal 10 includes a first wireless module 11-1 and a second wireless module 11-2. The first wireless module 11-1 is set to perform wireless communication on the first channel CH-1. The first wireless module 11-1 is connected to the first base station 20-1 and performs wireless communication with the first base station 20-1 on the first channel CH-1. On the other hand, the second wireless module 11-2 is set to perform wireless communication on a second channel CH-2 that does not overlap with the first channel CH-1. The second wireless module 11-2 is connected to the second base station 20-2 and performs wireless communication with the second base station 20-2 on the second channel CH-2.

[0019] By switching the wireless module 11 used when the wireless terminal 10 performs wireless communication with the base station 20, the channel used for wireless communication can be easily switched. One of the plurality of wireless modules 11 that is selectively used is hereinafter referred to as the "used module 11S". The used module 11S can also be referred to as the "selected module". Further, the process of switching the used module 11S in the wireless terminal 10 is hereinafter referred to as the "module switching process".

[0020] Next, consider a situation where there is a constraint (upper limit) on the transmission time ratio for each channel used by the wireless terminal 10. For example, in the country, there is a limit on the total transmission time when using the 920 MHz band, and the total transmission time per hour needs to be within 360 seconds. For a housing that switches and uses two non-overlapping channels, a total transmission time of up to 360 seconds per channel per hour, for a total of 720 seconds, is allowed. Therefore, in order to improve the throughput, the module switching process for switching the used module 11S in the wireless terminal 10 is effective.

[0021] The wireless communication system 1 according to this embodiment further includes a "control unit 100" that manages and controls the above module switching process. The control unit 100 selects one of the plurality of wireless modules 11 included in the wireless terminal 10 as the used module 11S. Further, the control unit 100 monitors and manages the transmission time and transmission time ratio of each channel of the plurality of wireless modules 11. Then, the control unit 100 performs a module switching process to switch the used module 11S so that the transmission time ratio of each channel of the plurality of wireless modules 11 does not exceed a predetermined upper limit.

[0022] For example, the control unit 100 may be included in the wireless terminal 10. As another example, the control unit 100 may be connected to the wireless terminal 10 and control the wireless terminal 10 from the outside. As yet another example, the control unit 100 may be included in the base station 20 and control the wireless terminal 10 via communication. As yet another example, the control unit 100 may be connected to the base station 20 and control the wireless terminal 10 via the base station 20. The control unit 100 can also be referred to as a "control device".

[0023] The control unit 100 may be a computer including one or more processors 110 (hereinafter simply referred to as "processor 110") and one or more storage devices 120 (hereinafter simply referred to as "storage device 120"). For example, the processor 110 includes a CPU (Central Processing Unit). The storage device 120 stores various information necessary for processing by the processor 110. Examples of the storage device 120 include volatile memory, non-volatile memory, HDD (Hard Disk Drive), SSD (Solid State Drive), and the like.

[0024] The control program 130 is a computer program executed by the processor 110. By executing the control program 130 by the processor 110, the functions of the control unit 100 are realized. The control program 130 is stored in the storage device 120. The control program 130 may be recorded on a computer-readable recording medium. The control program 130 may be provided to the control device 30 via a network.

[0025] FIG. 2 is a timing chart for explaining the outline of the module switching process according to the present embodiment. Here, the switching between the first wireless module 11-1 (first channel CH-1) and the second wireless module 11-2 (second channel CH-2) is considered.

[0026] During the period from time t1 to t2, the control unit 100 selects the first wireless module 11-1 as the used module 11S. The control unit 100 permits data transmission from the first wireless module 11-1 but prohibits data transmission from the second wireless module 11-2. That is, the period from time t1 to t2 is the transmission permission period PA for the first wireless module 11-1 and the transmission prohibition period PB for the second wireless module 11-2. The wireless terminal 10 uses the first wireless module 11-1 as the used module 11S to perform wireless communication with the first base station 20-1 on the first channel CH-1. On the other hand, the wireless terminal 10 stops data transmission from the second wireless module 11-2. Also, the control unit 100 constantly monitors the transmission time and transmission time rate of the first wireless module 11-1.

[0027] At time t2, the control unit 100 performs a module switching process and switches the used module 11S from the first wireless module 11-1 to the second wireless module 11-2.

[0028] During the period from time t2 to t3, the control unit 100 selects the second wireless module 11-2 as the used module 11S. The control unit 100 permits data transmission from the second wireless module 11-2 but prohibits data transmission from the first wireless module 11-1. That is, the period from time t2 to t3 is a transmission prohibition period PB for the first wireless module 11-1 and a transmission permission period PA for the second wireless module 11-2. The wireless terminal 10 uses the second wireless module 11-2 as the used module 11S to perform wireless communication with the second base station 20-2 on the second channel CH-2. On the other hand, the wireless terminal 10 stops data transmission from the first wireless module 11-1. Further, the control unit 100 constantly monitors the transmission time and transmission time ratio of the second wireless module 11-2.

[0029] At time t3, the control unit 100 performs module switching processing to switch the used module 11S from the second wireless module 11-2 to the first wireless module 11-1. The period from time t3 to t4 is the same as the period from time t1 to t2.

[0030] As triggers for the control unit 100 to execute the module switching processing, various examples can be considered as described later. For example, the control unit 100 may perform the module switching processing at regular intervals. As another example, the control unit 100 may perform the module switching processing when the communication quality of the used module 11S deteriorates. In any case, the control unit 100 according to the present embodiment performs the module switching processing so that the transmission time ratio of each wireless module 11 (each channel) does not exceed a predetermined upper limit. For this purpose, the control unit 100 monitors and manages the transmission time of each of the plurality of wireless modules 11 in the measurement period PM. Then, the control unit 100 performs the module switching processing so that the transmission time of each wireless module 11 in the measurement period PM becomes equal to or less than a certain value.

[0031] When the transmission time ratio of a certain wireless module 11 exceeds a predetermined upper limit, the control unit 100 stops the use of the wireless module 11. When the transmission time ratio of the entire wireless terminal 10 exceeds a predetermined upper limit, the control unit 100 stops data transmission from the wireless terminal 10.

[0032] <Effect> As described above, according to the present embodiment, the wireless terminal 10 includes a plurality of wireless modules 11 that perform wireless communication with each of the plurality of base stations 20 on different channels. The control unit 100 performs a module switching process for switching the used module 11S used by the wireless terminal 10 among the plurality of wireless modules 11. In particular, the control unit 100 performs the module switching process so that the transmission time ratio of each of the plurality of wireless modules 11 does not exceed a predetermined upper limit.

[0033] By switching the used module 11S among the plurality of wireless modules 11, the channel used for wireless communication can be easily switched. Since there is no need to switch channels within a single wireless module 11, the processing required for channel switching can be simplified. In addition, since the wireless terminal 10 does not need to be restarted for channel switching, the communication interruption time is reduced and a decrease in service quality is prevented.

[0034] In addition, since the control unit 100 accurately manages the transmission time ratio of each of the plurality of wireless modules 11, it is possible to use each channel up to the upper limit of the transmission time ratio. That is, the transmission time ratio of the entire wireless terminal 10 can be expanded, and the throughput can be effectively improved.

[0035] Furthermore, since the wireless terminal 10 includes a plurality of wireless modules 11, redundancy is ensured and reliability is improved.

[0036] Hereinafter, various embodiments will be described in more detail.

[0037] 2. Various Embodiments 2-1. First Embodiment FIG. 3 is a block diagram showing a configuration example of the wireless communication system 1 according to the first embodiment. In the first example, the control unit 100 is included in the wireless terminal 10. That is, the wireless terminal 10 is provided with the control unit 100. The wireless terminal 10 further includes a plurality of wireless modules 11, an upper layer 12, and a selector 13.

[0038] The control unit 100 selects one of the plurality of wireless modules 11 as the use module 11S. The control unit 100 notifies the selected use module 11S to the selector 13. The selector 13 receives the transmission data from the upper layer 12 and outputs the transmission data to the use module 11S. The selector 13 does not let the transmission data flow to the wireless modules 11 other than the use module 11S. The use module 11S transmits the transmission data from the upper layer 12, and the wireless modules 11 other than the use module 11S stop data transmission.

[0039] The control unit 100 monitors and manages the transmission time and transmission time rate of each of the plurality of wireless modules 11. Further, the control unit 100 performs a module switching process for switching the use module 11S. The trigger for the module switching process is arbitrary, but the control unit 100 performs the module switching process so that at least the transmission time rate of each of the plurality of wireless modules 11 does not exceed a predetermined upper limit.

[0040] FIG. 4 is a timing chart for explaining an example of the module switching process according to the first embodiment. Descriptions overlapping with FIG. 2 above are omitted as appropriate. The control unit 100 manages (monitors) the transmission time rate of each of the first wireless module 11-1 and the second wireless module 11-2. For example, the control unit 100 manages (monitors) the transmission time of each of the first wireless module 11-1 and the second wireless module 11-2 in the measurement period PM. Then, the control unit 100 performs a module switching process so that the transmission time of each wireless module 11 in the measurement period PM becomes a certain value or less. For example, when the transmission time rate of the use module 11S reaches a predetermined upper limit, the control unit 100 performs a module switching process. That is what is to be done.

[0041] FIG. 5 is a flowchart schematically showing processes related to module switching processing.

[0042] In step S100, the control unit 100 selects, according to the initial settings, one of the plurality of wireless modules 11 as the use module 11S. The wireless terminal 10 performs wireless communication with the base station 20 using the use module 11S.

[0043] In step S110, the control unit 100 determines whether there is a trigger for module switching processing. In other words, the control unit 100 determines whether a condition for executing the module switching processing (hereinafter referred to as "module switching condition") is satisfied. For example, the module switching condition is that the transmission time ratio of the use module 11S reaches a predetermined upper limit. Other examples of the module switching condition will be described later. If the module switching condition is not satisfied (step S110; No), the process returns to step S110. On the other hand, if the module switching condition is satisfied (step S110; Yes), the process proceeds to step S120.

[0044] In step S120, the control unit 100 performs module switching processing and switches the use module 11S.

[0045] In step S130, the wireless terminal 10 performs wireless communication with the base station 20 using the use module 11S after the switching. The process returns to step S110.

[0046] 2-2. Second Embodiment FIG. 6 is a block diagram showing a configuration example of the wireless communication system 1 according to the second embodiment. Descriptions overlapping with those of the first embodiment are omitted as appropriate. The control unit 100 is included in the wireless terminal 10. The control unit 100 performs module switching processing so that the transmission time ratio of each of the plurality of wireless modules 11 does not exceed a predetermined upper limit.

[0047] In the second embodiment, the control unit 100 includes a timer 140 that measures a fixed time. The control unit 100 may perform module switching processing at every fixed time with reference to the timer 140. That is, the module switching condition in step S110 described above may include "a fixed time has elapsed since the start of use of the used module 11S". Thereby, the transmission time of each wireless module 11 is ensured.

[0048] FIG. 7 is a timing chart for explaining an example of module switching processing according to the second embodiment. Descriptions overlapping with those in FIG. 2 above are omitted as appropriate. The control unit 100 performs module switching processing at every fixed time, that is, every time a timeout occurs. In addition, the control unit 100 also manages the transmission time rate of each wireless module 11, and performs module switching processing so that the transmission time rate does not exceed a predetermined upper limit.

[0049] 2-3. Third Embodiment FIG. 8 is a block diagram showing a configuration example of the wireless communication system 1 according to the third embodiment. Descriptions overlapping with those in the first embodiment are omitted as appropriate. The control unit 100 is included in the wireless terminal 10. The control unit 100 performs module switching processing so that the transmission time rate of each of at least the plurality of wireless modules 11 does not exceed a predetermined upper limit.

[0050] In the third embodiment, the control unit 100 includes a communication state monitoring unit 150. The communication state monitoring unit 150 monitors the communication state of each of the plurality of wireless modules 11. In particular, the communication state monitoring unit 150 monitors the communication quality of the used module 11S. Examples of the communication quality include throughput, communication delay, received radio wave intensity, carrier sense waiting time, and the like. When the communication quality of the used module 11S drops below a threshold value, the control unit 100 may perform module switching processing. That is, the module switching condition in step S110 described above may include "the communication quality of the used module 11S drops below a threshold value". Thereby, it becomes possible to avoid a decrease in communication quality.

[0051] FIG. 9 is a timing chart for explaining an example of module switching processing according to the third embodiment. Descriptions overlapping with those in FIG. 2 above are omitted as appropriate. The control unit 100 monitors the communication state, and when the communication quality of the used module 11S drops below the threshold value, it performs module switching processing. Further, the control unit 100 also manages the transmission time ratio of each wireless module 11, and performs module switching processing so that the transmission time ratio does not exceed a predetermined upper limit.

[0052] 2-4. Fourth Embodiment FIGS. 10 and 11 are block diagrams showing a configuration example of the wireless communication system 1 according to the fourth embodiment. Descriptions overlapping with those in the first embodiment are omitted as appropriate. The control unit 100 is included in the wireless terminal 10. The control unit 100 performs module switching processing so that the transmission time ratio of each of at least the plurality of wireless modules 11 does not exceed a predetermined upper limit.

[0053] In the fourth embodiment, there are a plurality of upper layers 12 of the data transmission source. And a plurality of wireless modules 11 and a plurality of upper layers 12 are associated with each other. That is, the plurality of wireless modules 11 are assigned to each of the plurality of upper layers 12. The plurality of wireless modules 11 are used for data transmission from each of the plurality of upper layers 12. For example, in FIG. 10, the first wireless module 11-1 is used for data transmission from the first upper layer 12-1 (e.g., IoT). The second wireless module 11-2 is used for data transmission from the second upper layer 12-2 (e.g., file transfer). Thereby, the channel can be used properly according to the quality required by the upper layer 12.

[0054] As shown in FIG. 10, the wireless terminal 10 may include a routing unit that distributes transmission data from a plurality of upper layers 12 to a plurality of wireless modules 11. As another example, as shown in FIG. 11, it is also possible to transmit data of a plurality of TCP connections by different wireless modules 11 by Multipath-TCP (MPTCP).

[0055] The wireless terminal 10 includes a plurality of queues 14 for each of the plurality of wireless modules 11. For example, the first queue 14-1 is provided for the first wireless module 11-1, and the second queue 14-2 is provided for the second wireless module 11-2. When the use of the wireless modules 11 other than the use module 11S is stopped, transmission waiting may occur in the corresponding queue 14.

[0056] FIG. 12 is a timing chart for explaining a method for suppressing the delay caused by transmission waiting in the queue 14. Descriptions overlapping with those in FIG. 2 above are omitted as appropriate. As shown in FIG. 12, the frequency of the channel switching process is set higher compared to the case of other embodiments. The period of the channel switching process may be set by a timer. By setting the frequency of the channel switching process high, the transmission waiting in each queue 14 is suppressed. Also, the data transfer timing from the queue 14 may be adjusted so that data discard does not occur in the wireless module 11.

[0057] 2-5. Fifth Embodiment FIG. 13 is a block diagram showing a configuration example of the wireless communication system 1 according to the fifth embodiment. Descriptions overlapping with those in the first embodiment are omitted as appropriate. In the fifth embodiment, the control unit 100 is connected to a plurality of base stations 20. The control unit 100 manages and controls the wireless terminal 10 via the base stations 20. In particular, the control unit 100 manages and sets (designates) the transmission permission timing of each wireless module 11 of the wireless terminal 10.

[0058] More specifically, the control unit 100 assigns non-overlapping transmission permission timings (transmission permission periods PA) to the plurality of wireless modules 11 of the wireless terminal 10. In other words, non-overlapping transmission prohibition timings (transmission prohibition periods PB) are assigned to the plurality of wireless modules 11 of the wireless terminal 10. At this time, the control unit 100 assigns the transmission permission timing so that the transmission time ratio of each wireless module 11 does not exceed a predetermined upper limit. Then, the control unit 100 sets non-overlapping transmission permission timings for the plurality of wireless modules 11 via each of the plurality of base stations 20. Each wireless module 11 of the wireless terminal 10 operates as the used module 11S at the set transmission permission timing and stops data transmission outside the transmission permission timing.

[0059] FIG. 14 is a timing chart for explaining an example of the timing setting process according to the fifth embodiment. Connection processing is performed between the first wireless module 11-1 and the first base station 20-1. Also, connection processing is performed between the second wireless module 11-2 and the second base station 20-2.

[0060] The control unit 100 assigns non-overlapping transmission permission timings (transmission permission periods PA) to the first wireless module 11-1 and the second wireless module 11-2. The control unit 100 notifies the first base station 20-1 of the transmission permission timing of the first wireless module 11-1. The first base station 20-1 sets the transmission permission timing for the first wireless module 11-1. Such setting is possible, for example, by using TWT (Target Wake Time). Similarly, the control unit 100 notifies the second base station 20-2 of the transmission permission timing of the second wireless module 11-2. The second base station 20-2 sets the transmission permission timing for the second wireless module 11-2. Each of the first wireless module 11-1 and the second wireless module 11-2 operates as the used module 11S at the set transmission permission timing and stops data transmission outside the transmission permission timing.

[0061] During communication, the control unit 100 may update the transmission permission timing of each wireless module 11. For example, the control unit 100 grasps the communication quality and traffic status of each of the plurality of base stations 20. The traffic status may include the transmission time ratio of each wireless module 11 and the transmission time ratio of the base station 20. The control unit 100 updates the transmission permission timing of each wireless module 11 based on the communication quality and traffic status of each base station 20. For example, the control unit 100 updates the transmission permission timing so that the transmission time ratio of each wireless module 11 does not exceed a predetermined upper limit.

[0062] FIG. 15 is a flowchart showing the processing by the control unit 100 according to the fifth embodiment.

[0063] In step S140, the control unit 100 determines whether it has received a connection state update notification from any of the base stations 20. The connection state update notification is a notification indicating that the connection state between the base station 20 and the wireless terminal 10 (wireless module 11) has been updated. If the connection state update notification is received (step S140; Yes), the process proceeds to step S150.

[0064] In step S150, the control unit 100 determines the transmission permission timing of each wireless module 11 under the jurisdiction of the base station 20. At this time, the transmission permission timing of each wireless module 11 is determined so that the transmission permission timings do not overlap among the plurality of wireless modules 11.

[0065] In step S160, the control unit 100 sets the transmission permission timing to each wireless module 11 via the base station 20.

[0066] 2-6. Sixth Embodiment FIG. 16 is a block diagram showing a configuration example of the wireless communication system 1 according to the sixth embodiment. Descriptions overlapping with those of the first embodiment are omitted as appropriate. In the sixth embodiment, the control unit 100 is connected to a plurality of base stations 20. The control unit 100 manages and controls the wireless terminal 10 via the base station 20.

[0067] In the sixth embodiment, in particular, consider the connection process between the wireless module 11 and the base station 20. When the wireless module 11 connects to the base station 20, assume that there are multiple base stations 20 as connection destination candidates. In this case, the control unit 100 designates one optimal base station from among the multiple base stations 20 (connection destination candidates).

[0068] More specifically, the control unit 100 constantly monitors the states of the multiple base stations 20. The control unit 100 sets the priority of each base station 20 based on the state of each base station 20 (e.g., congestion situation, downlink traffic, transmission time ratio as a base station, etc.). For example, the control unit 100 grasps the congestion situation of the base station 20 based on the available bandwidth, the number of connected terminals, etc. Then, the control unit 100 lowers the priority of the base station 20 with less wireless resource margin. As another example, when there are also constraints on the transmission time ratio regarding the downlink traffic from the base station 20 to the wireless terminal 10, the control unit 100 grasps the current situation of the downlink traffic and the transmission time ratio. Then, the control unit 100 lowers the priority of the base station 20 with less margin in the transmission time ratio.

[0069] The control unit 100 selects one base station 20 as the connection destination of the wireless module 11 according to the priority of each base station 20. For example, in FIG. 16, the control unit 100 is connected to the first base station 20-1, the second base station 20-2, and the third base station 20-3. If the priority of the first base station 20-1 is the highest among these, the control unit 100 selects the first base station 20-1 as the connection destination. Thereby, it becomes possible to appropriately select the connection destination of the wireless module 11 according to the situation on the base station 20 side.

[0070] FIG. 17 is a timing chart for explaining an example of connection processing according to the sixth embodiment. For example, the first wireless module 11-1 of the wireless terminal 10 queries the surrounding base stations 20 for the connection destination. Each base station 20 notifies the reception of the connection destination query to the control unit 100. The control unit 100 selects the connection destination of the first wireless module 11-1 from among the plurality of base stations 20 according to the priorities of the plurality of base stations 20. Here, for example, the priority of the first base station 20-1 is the highest, and the first base station 20-1 is selected. The control unit 100 instructs the selected first base station 20-1 to respond to the first wireless module 11-1. In accordance with the instruction from the control unit 100, the first base station 20-1 returns a response to the first wireless module 11-1, which is the source of the connection destination query. As a result, connection processing is performed between the first wireless module 11-1 and the first base station 20-1.

[0071] Thereafter, the second wireless module 11-2 of the wireless terminal 10 queries the surrounding base stations 20 for the connection destination. Each base station 20 notifies the reception of the connection destination query to the control unit 100. The control unit 100 selects the connection destination of the second wireless module 11-2 from among the plurality of base stations 20 according to the priorities of the plurality of base stations 20. Here, for example, the priority of the second base station 20-2 is the highest, and the second base station 20-2 is selected. The control unit 100 instructs the selected second base station 20-2 to respond to the second wireless module 11-2. In accordance with the instruction from the control unit 100, the second base station 20-2 returns a response to the second wireless module 11-2, which is the source of the connection destination query. As a result, connection processing is performed between the second wireless module 11-2 and the second base station 20-2.

[0072] FIG. 18 is a flowchart showing the processing by the control unit 100 according to the sixth embodiment.

[0073] In step S170, the control unit 100 determines whether it has received a connection destination inquiry reception notification from at least one base station 20. The connection destination inquiry reception notification is a notification indicating that the base station 20 has received a connection destination inquiry from the wireless terminal 10 (wireless module 11). If the connection destination inquiry reception notification is received (step S170; Yes), the process proceeds to step S180.

[0074] In step S180, the control unit 100 selects one base station 20 to be the connection destination of the wireless module 11 based on the priority of each base station 20.

[0075] In step S190, the control unit 100 instructs the selected base station 20 to respond to the wireless module 11 that is the source of the connection destination inquiry.

[0076] 3. Summary As described above, according to this embodiment, the wireless terminal 10 includes a plurality of wireless modules 11 that perform wireless communication with each of the plurality of base stations 20 on different channels. The control unit 100 performs module switching processing for switching the used module 11S used by the wireless terminal 10 among the plurality of wireless modules 11. In particular, the control unit 100 performs module switching processing so that the transmission time ratio of each of the plurality of wireless modules 11 does not exceed a predetermined upper limit.

[0077] By switching the used module 11S among the plurality of wireless modules 11, the channel used for wireless communication can be easily switched. Since there is no need to switch channels within a single wireless module 11, it is possible to simplify the processing required for channel switching. Also, since restarting the wireless terminal 10 is not required for channel switching, the communication interruption time is reduced and a degradation in service quality is prevented.

[0078] In addition, since the control unit 100 accurately manages the transmission time ratio of each of the plurality of wireless modules 11, it is possible to use each channel up to the upper limit of the transmission time ratio. That is, it is possible to expand the transmission time ratio of the entire wireless terminal 10 and effectively improve the throughput.

[0079] Furthermore, since the wireless terminal 10 includes a plurality of wireless modules 11, redundancy is ensured and the reliability is improved.

Explanation of Signs

[0080] 1…Wireless communication system, 10…Wireless terminal, 11…Wireless module 11, 11-1…First wireless module, 11-2…Second wireless module, 11S…Used module, 12…Upper layer, 13…Selector, 20…Base station, 20-1…First base station, 20-2…Second base station, 100…Control unit, 110…Processor, 120…Storage device, 130…Control program, 140…Timer, 150…Communication state monitoring unit, PA…Transmission permission period, PB…Transmission prohibition period

Claims

1. A wireless terminal comprising a plurality of wireless modules that perform wireless communication with each of a plurality of base stations on different channels, a control unit, and comprising: The wireless terminal uses one of the plurality of wireless modules as a use module, and stops data transmission from wireless modules other than the use module. The control unit switches the use module in the wireless terminal so that the transmission time rate of each of the plurality of wireless modules does not exceed a predetermined upper limit. When the wireless terminal switches the use module, it also switches the base station of the communication partner. A wireless communication system.

2. The wireless communication system according to claim 1, wherein the control unit monitors the transmission time of each of the plurality of wireless modules in a measurement period, and switches the use module in the wireless terminal so that the transmission time of each of the plurality of wireless modules in the measurement period is equal to or less than a certain value. A wireless communication system.

3. The wireless communication system according to claim 1 or 2, wherein the control unit determines whether a module switching condition is satisfied, and switches the use module when the module switching condition is satisfied. The module switching condition includes that a certain time has elapsed since the start of use of the use module, or that the communication quality of the use module has dropped below a threshold value. A wireless communication system.

4. The wireless communication system according to claim 1 or 2, wherein the plurality of wireless modules are each assigned to a plurality of upper layers of the data transmission source and are used for data transmission from each of the plurality of upper layers. A wireless communication system.

5. The wireless communication system according to claim 1 or 2, wherein the control unit is connected to the plurality of base stations, the control unit sets non-overlapping transmission permission timings for the plurality of wireless modules of the wireless terminal via each of the plurality of base stations, each of the plurality of wireless modules operates as the use module at the transmission permission timing and stops data transmission outside the transmission permission timing. A wireless communication system.

6. A wireless terminal control method for controlling a wireless terminal comprising a plurality of wireless modules that perform wireless communication with each of a plurality of base stations on different channels, the method comprising: a process of selecting one of the plurality of wireless modules as a use module, A process for stopping data transmission from a wireless module other than the usage module, A process for switching the usage module in the wireless terminal so that the transmission time ratio of each of the plurality of wireless modules does not exceed a predetermined upper limit, A process for switching the base station of the communication partner when switching the usage module are included in a wireless terminal control method.

7. A control device for controlling a wireless terminal including a plurality of wireless modules that perform wireless communication with different channels from each of a plurality of base stations, comprising one or more processors, wherein the one or more processors perform a process of selecting one of the plurality of wireless modules as a usage module, perform a process of stopping data transmission from a wireless module other than the usage module, perform a process of switching the usage module in the wireless terminal so that the transmission time ratio of each of the plurality of wireless modules does not exceed a predetermined upper limit, perform a process of switching the base station of the communication partner when switching the usage module and is configured to execute a control device.

8. A control program executed by a computer to cause the computer to implement the control device according to Claim 7.

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