Wireless communication system, wireless communication control method, and base station

Abstract

This wireless communication system comprises: a wireless terminal that comprises a plurality of wireless modules for performing wireless communication in channels differing from one another; a base station that performs wireless communication with the plurality of wireless modules; and a plurality of relay devices that relay the wireless communication between the base station and each of the plurality of wireless modules. 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 base station determines a usage schedule for each of the plurality of wireless modules such that the transmission time ratio of each of the plurality of wireless modules of the wireless terminal does not exceed a prescribed upper limit. In addition, the base station notifies each wireless module of information relating to the determined usage schedule. Each wireless module operates as the usage module in accordance with the usage schedule determined by the base station.

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 including 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 recent spread of IoT (Internet of Things) terminals, the use cases of transmitting data from the wireless terminal side to the base station are increasing.

[0003] In relation to wireless communication for IoT, the use of unlicensed Sub-1GHz bands has been institutionalized in various countries around the world (see Non-Patent Document 1). 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. Also, 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 Japan, there is a limit on the total transmission time when using the 920MHz band, and the total transmission time per hour must be within 360 seconds. Wireless communication devices restrict data transmission to comply with this total transmission time limit, and therefore throughput is also limited. However, for wireless communication device enclosures that switch between two non-overlapping channels, a total transmission time of up to 360 seconds per channel per hour, for a total of 720 seconds, is permitted. Therefore, to improve throughput, it is conceivable to perform wireless communication while changing the channels used by the wireless communication device enclosure. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] "Standard Specifications for Radio Equipment for Telemetry, Telecontrol, and Data Transmission in the 920MHz Band," Association of Radio Industries and Businesses (ARIB), ARIB STD-T108 Version 1.3, April 12, 2019. [Overview of the project] [Problems that the invention aims to solve]

[0007] Let's consider the case where a wireless terminal transmits data to a base station via a relay device. In situations where there are constraints on the transmission time rate for each channel, throughput can be improved by switching the channel used by the wireless terminal. However, switching the channel used within the wireless module of the wireless terminal requires complex processing.

[0008] One object of the present invention is to provide a technology that can simplify the process of switching channels used by wireless terminals. [Means for solving the problem]

[0009] The first perspective relates to wireless communication systems. The wireless communication system is A wireless terminal equipped with multiple wireless modules that perform wireless communication on different channels, A base station that performs wireless communication with multiple wireless modules, Multiple relay devices that relay wireless communication between each of the multiple wireless modules and the base station It is equipped with. The wireless terminal uses one of several wireless modules as the active module and stops transmitting data from the other wireless modules. The base station is, To ensure that the transmission time rate of each of the multiple wireless modules in a wireless terminal does not exceed a predetermined upper limit, the usage schedule for each of the multiple wireless modules is determined. The wireless terminal will be notified of the usage schedule. It is configured in this way. Each of the multiple wireless modules operates as a module in use according to the usage schedule determined by the base station.

[0010] The second aspect relates to a wireless communication control method for controlling wireless communication between a wireless terminal and a base station via multiple relay devices. The wireless terminal is equipped with multiple wireless modules that communicate wirelessly on different channels, and one of the multiple wireless modules is designated as the active module, stopping data transmission from the other wireless modules. Multiple relay devices relay wireless communication between each of the multiple wireless modules and the base station. Wireless communication control method is, At a base station, the usage schedule for each of the multiple wireless modules of a wireless terminal is determined so that the transmission time rate of each of the multiple wireless modules does not exceed a predetermined upper limit. The base station notifies wireless terminals of the usage schedule information, The operation of each of the multiple radio modules as a usage module is performed according to the usage schedule determined by the base station. Includes.

[0011] The third aspect relates to a base station that performs wireless communication with a wireless terminal via a plurality of relay devices. The wireless terminal includes a plurality of wireless modules that perform wireless communication on different channels, 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 plurality of relay devices relay wireless communication between each of the plurality of wireless modules and the base station. The base station includes a control unit. The control unit determines the usage schedule for each of the plurality of wireless modules so that the transmission time rate of each of the plurality of wireless modules of the wireless terminal does not exceed a predetermined upper limit, notifies the wireless terminal of the information on the usage schedule, and causes each of the plurality of wireless modules to operate as a used module according to the usage schedule configured as follows.

Advantages of the Invention

[0012] According to the present invention, the wireless terminal includes a plurality of wireless modules that perform wireless communication on different channels. By switching the used 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

[0013] [Figure 1] It is a block diagram showing the basic configuration of a wireless communication system according to an embodiment. [Figure 2] It is a timing chart for explaining the outline of data transmission control involving module switching processing according to an embodiment. [Figure 3] It is a block diagram for explaining the outline of a control unit according to an embodiment. [Figure 4] It is a block diagram showing a configuration example of a control unit according to an embodiment. [Figure 5]It is a block diagram showing a configuration example of a wireless communication system according to an embodiment. [Figure 6] It is a conceptual diagram for explaining a first processing example by a control unit according to an embodiment. [Figure 7] It is a timing chart for explaining a first processing example by a control unit according to an embodiment. [Figure 8] It is a flowchart showing a first processing example by a control unit according to an embodiment. [Figure 9] It is a conceptual diagram for explaining a second processing example by a control unit according to an embodiment. [Figure 10] It is a timing chart for explaining a second processing example by a control unit according to an embodiment. [Figure 11] It is a flowchart showing a second processing example by a control unit according to an embodiment. [Figure 12] It is a conceptual diagram for explaining a third processing example by a control unit according to an embodiment. [Figure 13] It is a flowchart showing a third processing example by a control unit according to an embodiment.

Embodiments for Carrying Out the Invention

[0014] Embodiments of the present invention will be described with reference to the accompanying drawings.

[0015] 1. Overview of the Wireless Communication System 1-1. Basic Configuration Figure 1 is a block diagram showing the basic configuration of a wireless communication system 1 according to this embodiment. The wireless communication system 1 includes a wireless terminal 10, a base station 20, and a plurality of relay devices 30. The wireless terminal 10 and the base station 20 communicate wirelessly with each other via the relay devices 30. In other words, the relay devices 30 relay wireless communication between the wireless terminal 10 and the base station 20. The relay devices 30 also make it possible to accommodate wireless terminals 10 that are far away from the base station 20. For example, the wireless communication system 1 is a wireless LAN system. For example, the wireless communication system 1 uses the unlicensed Sub-1GHz band for wireless communication. For example, the wireless communication system 1 uses the 920MHz band for wireless communication.

[0016] The wireless terminal 10 according to this embodiment can perform wireless communication by switching between multiple channels (frequency channels). More specifically, the wireless terminal 10 comprises multiple 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). Each of the multiple wireless modules 11 is connected to a multiple relay device 30. In other words, the multiple wireless modules 11 perform wireless communication with a single base station 20 via each of the multiple relay devices 30. To put it another way, the multiple relay devices 30 relay the wireless communication between each of the multiple wireless modules 11 and the single base station 20.

[0017] In the example shown in Figure 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 configured to perform wireless communication on the first channel CH-1. The first wireless module 11-1 is connected to the first relay device 30-1 and performs wireless communication with the base station 20 on the first channel CH-1 via the first relay device 30-1. On the other hand, the second wireless module 11-2 is configured to perform wireless communication on the second channel CH-2, which does not overlap with the first channel CH-1. The second wireless module 11-2 is connected to the second relay device 30-2 and performs wireless communication with the base station 20 on the second channel CH-2 via the second relay device 30-2.

[0018] 1-2. Module switching process The channel used for wireless communication can be easily switched by switching the wireless module 11 used by the wireless terminal 10. One of the multiple wireless modules 11 that is selectively used will be referred to below as the "used module 11S". The used module 11S can also be referred to as the "selected module". Furthermore, the process of switching the used module 11S in the wireless terminal 10 will be referred to below as the "module switching process".

[0019] The wireless terminal 10 transmits data by using one of the multiple wireless modules 11 as the user module 11S. More specifically, in addition to the multiple wireless modules 11, the wireless terminal 10 includes a higher layer 12 and a selector 13. The selector 13 receives transmission data from the higher layer 12 and outputs the transmission data to the user module 11S. The selector 13 does not pass the transmission data to any wireless module 11 other than the user module 11S. The user module 11S transmits the transmission data from the higher layer 12, and the wireless modules 11 other than the user module 11S stop transmitting data.

[0020] Next, let's consider a situation where there are constraints (upper limits) on the transmission time rate for each channel used by the wireless terminal 10. For example, in Japan, there is a limit on the total transmission time when using the 920MHz band, and the total transmission time per hour must be within 360 seconds. For a chassis that switches between two non-overlapping channels, a total transmission time of up to 360 seconds per hour for each channel, totaling 720 seconds, is permitted. Therefore, a module switching process that switches the module 11S used by the wireless terminal 10 is effective in improving throughput.

[0021] Figure 2 is a timing chart illustrating the overview of data transmission control involving module switching processing according to this embodiment. Here, we consider the switching between the first wireless module 11-1 (first channel CH-1) and the second wireless module 11-2 (second channel CH-2).

[0022] During the period from time t1 to t2, the first radio module 11-1 is selected as the module 11S to be used. Data transmission from the first radio module 11-1 is permitted, but data transmission from the second radio module 11-2 is prohibited. In other words, the period from time t1 to t2 is the transmission permission period PA for the first radio module 11-1 and the transmission prohibition period PB for the second radio module 11-2. The radio terminal 10 uses the first radio module 11-1 as the module 11S and performs wireless communication with the base station 20 on the first channel CH-1 via the first relay device 30-1. At the same time, the radio terminal 10 stops transmitting data from the second radio module 11-2.

[0023] At time t2, the wireless terminal 10 switches the module 11S being used from the first wireless module 11-1 to the second wireless module 11-2.

[0024] During the period from time t2 to t3, the second radio module 11-2 is selected as the module 11S to be used. Data transmission from the second radio module 11-2 is permitted, but data transmission from the first radio module 11-1 is prohibited. In other words, the period from time t2 to t3 is a transmission prohibition period PB for the first radio module 11-1 and a transmission permission period PA for the second radio module 11-2. The radio terminal 10 uses the second radio module 11-2 as the module 11S to communicate wirelessly with the base station 20 on the second channel CH-2 via the second relay device 30-2. At the same time, the radio terminal 10 stops transmitting data from the first radio module 11-1.

[0025] At time t3, the wireless terminal 10 switches the module 11S being used 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.

[0026] The transmission permission period PA does not overlap between the first radio module 11-1 and the second radio module 11-2. Similarly, the transmission prohibition period PB does not overlap between the first radio module 11-1 and the second radio module 11-2.

[0027] Furthermore, the transmission time ratio of each wireless module 11 can be calculated from the transmission time of each wireless module 11 in the measurement cycle PM.

[0028] To realize the module switching process described above, the wireless communication system 1 according to this embodiment includes a "control unit 100" that manages and controls the module switching process.

[0029] Figure 3 is a block diagram illustrating the overview of the control unit 100. The control unit 100 monitors and manages the transmission time and transmission time rate of each of the multiple wireless modules 11 (multiple channels) of the wireless terminal 10. The control unit 100 then determines the usage schedule for each of the multiple wireless modules 11 so that the transmission time rate of each of the multiple wireless modules 11 of the wireless terminal 10 does not exceed a predetermined upper limit. For example, the usage schedule includes a transmission permission period (PA) assigned to each wireless module 11. The usage schedule can also be called the transmission timing. Various examples of triggers for module switching processing are possible, but at a minimum, the usage schedule is determined so that the transmission time rate of each wireless module 11 does not exceed a predetermined upper limit.

[0030] Furthermore, the control unit 100 controls the wireless terminal 10 to perform module switching processing according to the determined usage schedule. In other words, the control unit 100 controls the wireless terminal 10 to switch the usage modules 11S according to the determined usage schedule. The wireless terminal 10 switches the usage modules 11S according to the usage schedule determined by the control unit 100. Each wireless module 11 operates as a usage module 11S according to the usage schedule determined by the control unit 100.

[0031] 1-3. Effects As described above, according to this embodiment, the wireless terminal 10 includes a plurality of wireless modules 11 that perform wireless communication on different channels. By switching the module 11S used among the plurality of wireless modules 11, the channel used for wireless communication can be easily switched. Since it is not necessary 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 when switching channels, the communication downtime is reduced and a deterioration in service quality is prevented.

[0032] Furthermore, according to this embodiment, the control unit 100 determines the usage schedule for each wireless module 11 so that the transmission time rate of each wireless module 11 of the wireless terminal 10 does not exceed a predetermined upper limit. Because the control unit 100 accurately manages the transmission time rate of each wireless module 11, it becomes possible to use each channel up to the upper limit of the transmission time rate. In other words, it becomes possible to expand the transmission time rate of the wireless terminal 10 as a whole and effectively improve throughput.

[0033] Furthermore, according to this embodiment, since the wireless terminal 10 is equipped with multiple wireless modules 11, redundancy is ensured and reliability is improved.

[0034] Furthermore, according to this embodiment, the relay device 30 can also accommodate wireless terminals 10 that are far away from the base station 20.

[0035] 2. Example of Control Unit Configuration Figure 4 is a block diagram showing an example configuration of the control unit 100 according to this embodiment. In the example shown in Figure 4, the control unit 100 is a computer equipped with 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 devices 120"). For example, the processor 110 includes a CPU (Central Processing Unit). The storage devices 120 store various information necessary for processing by the processor 110. Examples of storage devices 120 include volatile memory, non-volatile memory, HDD (Hard Disk Drive), SSD (Solid State Drive), etc.

[0036] The control program 130 is a computer program executed by the processor 110. The processor 110 executes the control program 130, thereby realizing the functions of the control unit 100. The control program 130 is stored in the storage device 120. The control program 130 may also be recorded on a computer-readable recording medium. The control program 130 may also be provided to the control unit 100 via a network.

[0037] The storage device 120 stores module switching management information 200. Module switching management information 200 is information for managing the module switching process. For example, module switching management information 200 includes the transmission time and transmission time rate for each of the multiple wireless modules 11 of the wireless terminal 10. Module switching management information 200 may also include the usage schedule for each of the multiple wireless modules 11. For example, the usage schedule includes the transmission permission period PA (e.g., a combination of start time and duration) assigned to each wireless module 11. The usage schedule can also be called the transmission timing.

[0038] The storage device 120 may also store relay device status information 300. The relay device status information 300 indicates the status of each relay device 30 connected to the base station 20. The relay device status information 300 includes identification information for each relay device 30. It also includes information (number, etc.) of the wireless terminals 10 and wireless modules 11 under each relay device 30. As another example, the relay device status information 300 may include the distance between each relay device 30 and the wireless terminals 10 under it. As yet another example, the relay device status information 300 may include the traffic status and transmission time rate of each relay device 30. As yet another example, the relay device status information 300 may include the channel used and transmission power of each relay device 30. The control unit 100 communicates with each relay device 30 and obtains the relay device status information 300 from each relay device 30.

[0039] 3. Example of processing when the base station includes a control unit. It is cumbersome and inefficient for the wireless terminal 10 itself to manage the transmission time rate of each wireless module 11 and determine the usage schedule for each wireless module 11. Therefore, the following discussion will consider the case where the base station 20 includes a control unit 100.

[0040] Figure 5 is a block diagram showing an example configuration of the wireless communication system 1 when the base station 20 includes a control unit 100. Because the base station 20 includes a control unit 100, it becomes possible to efficiently determine the usage schedule of each wireless module 11 of each wireless terminal 10. In addition, complex processing is not required at the wireless terminal 10.

[0041] The following describes in detail the processing in the wireless communication system 1 shown in Figure 5.

[0042] 3-1. First Processing Example Figure 6 is a conceptual diagram illustrating a first processing example by the control unit 100 included in the base station 20. Figure 7 is a timing chart illustrating a first processing example by the control unit 100 included in the base station 20.

[0043] The control unit 100 monitors the transmission time and transmission time rate of each of the multiple wireless modules 11 of the wireless terminal 10 and updates the module switching management information 200 (see Figure 4). The control unit 100 also determines the usage schedule for each of the multiple wireless modules 11. For example, the control unit 100 basically determines the usage schedule for each wireless module 11 so that the module 11S being used switches at regular intervals. However, based on the module switching management information 200, the control unit 100 determines the usage schedule for each wireless module 11 so that the transmission time rate of each wireless module 11 does not exceed a predetermined upper limit. The trigger for the module switching process is arbitrary, but the usage schedule is determined so that the transmission time rate of each wireless module 11 does not exceed a predetermined upper limit.

[0044] The usage schedule includes a transmit permission period PA assigned to each radio module 11, i.e., a transmit permission period PA during which each radio module 11 operates as a usage module 11S. The transmit permission period PA is defined, for example, by a combination of start time and duration. The transmit permission periods PA are set so as not to overlap among multiple radio modules 11.

[0045] The control unit 100 instructs the wireless terminal 10 to switch the module 11S in use according to the determined usage schedule. More specifically, the control unit 100 generates schedule information SKD indicating the determined usage schedule and notifies the wireless terminal 10 of the schedule information SKD. Each of the multiple wireless modules 11 operates as a module 11S in use according to the usage schedule determined by the control unit 100. In other words, the wireless terminal 10 switches the module 11S in use according to the usage schedule determined by the control unit 100.

[0046] In the examples shown in Figures 6 and 7, the first wireless module 11-1 and the second wireless module 11-2 of the wireless terminal 10 are connected to the first relay device 30-1 and the second relay device 30-2, respectively.

[0047] The control unit 100 determines the usage schedule for the first wireless module 11-1. At this time, based on the module switching management information 200, the control unit 100 determines the usage schedule for the first wireless module 11-1 so that the transmission time rate of the first wireless module 11-1 does not exceed a predetermined upper limit. Then, the control unit 100 transmits the first schedule information SKD-1 regarding the usage schedule of the first wireless module 11-1 to the first relay device 30-1 connected to the first wireless module 11. The first relay device 30-1 receives the first schedule information SKD-1 and transmits it to the first wireless module 11-1. In other words, the control unit 100 notifies the first wireless module 11-1 of the first schedule information SKD-1 via the first relay device 30-1. At this time, TWT (Target Wake Time) may be used. The first wireless module 11-1 operates as the module 11S in accordance with the first schedule information SKD-1 determined by the control unit 100. In other words, the first radio module 11-1 operates as module 11S during the transmission permission period PA determined by the control unit 100. The first relay device 30-1 relays the radio communication between the base station 20 and the first radio module 11-1 according to the first schedule information SKD-1.

[0048] Furthermore, the control unit 100 determines the usage schedule for the second wireless module 11-2. At this time, based on the module switching management information 200, the control unit 100 determines the usage schedule for the second wireless module 11-2 so that the transmission time rate of the second wireless module 11-2 does not exceed a predetermined upper limit. Then, the control unit 100 transmits the second schedule information SKD-2 regarding the usage schedule of the second wireless module 11-2 to the second relay device 30-2 connected to the second wireless module 11. The second relay device 30-2 receives the second schedule information SKD-2 and transmits it to the second wireless module 11-2. In other words, the control unit 100 notifies the second wireless module 11-2 of the second schedule information SKD-2 via the second relay device 30-2. At this time, TWT may be used. The second wireless module 11-2 operates as the module 11S in accordance with the second schedule information SKD-2 determined by the control unit 100. In other words, the second radio module 11-2 operates as module 11S during the transmission permission period PA determined by the control unit 100. The second relay device 30-2 relays the radio communication between the base station 20 and the second radio module 11-2 according to the second schedule information SKD-2.

[0049] The control unit 100 may also take into account the timing of downlink traffic from the base station 20 and determine the schedule to be consistent with the timing of downlink traffic from the base station 20.

[0050] During communication, the control unit 100 may update the usage schedule for each wireless module 11. For example, the control unit 100 may be aware of the communication quality and traffic status of the base station 20. The traffic status may include the transmission time rate of the base station 20. Based on the communication quality and traffic status of the base station 20, the control unit 100 updates the usage schedule for each wireless module 11. Then, the control unit 100 notifies the wireless module 11 of schedule information SKD indicating the updated usage schedule.

[0051] Figure 8 is a flowchart showing a first example of processing performed by the control unit 100 included in the base station 20.

[0052] In step S110, the control unit 100 determines whether or not it has received a connection status update notification from any of the relay devices 30. A connection status update notification is a notification indicating that the connection status between the relay device 30 and the wireless terminal 10 (wireless module 11) has been updated. If a connection status update notification is received (step S110; Yes), the process proceeds to step S111.

[0053] In step S111, the control unit 100 determines the usage schedule for each wireless module 11 under the relay device 30. At this time, the usage schedule for each wireless module 11 is determined so that the transmission permission periods (PAs) do not overlap among the multiple wireless modules 11.

[0054] In step S112, the control unit 100 notifies the corresponding wireless module 11 of the schedule information SKD indicating the usage schedule via the relay device 30.

[0055] According to the first processing example, the control unit 100 determines the usage schedule for each wireless module 11 so that the transmission time rate of each wireless module 11 of the wireless terminal 10 does not exceed a predetermined upper limit. Because the control unit 100 accurately manages the transmission time rate of each wireless module 11, it becomes possible to use each channel up to the upper limit of the transmission time rate. In other words, it becomes possible to expand the transmission time rate of the wireless terminal 10 as a whole and effectively improve throughput.

[0056] Furthermore, since the base station 20 includes the control unit 100, it becomes possible to efficiently determine the usage schedule for each wireless module 11 of each wireless terminal 10. In addition, complex processing is not required in the wireless terminal 10.

[0057] 3-2. Second Processing Example In the second processing example, we will consider the connection process between the wireless module 11 and the relay device 30 in particular. When the wireless module 11 connects to the relay device 30, assume that there are multiple relay devices 30 as potential connection destinations. In this case, the control unit 100 selects the optimal one from among the multiple relay devices 30 (potential connection destinations).

[0058] More specifically, the control unit 100 constantly monitors the status of each relay device 30 connected to the base station 20 and updates the relay device status information 300 (see Figure 4). For example, the relay device status information 300 includes information on the wireless terminals 10 and wireless modules 11 under each relay device 30. As another example, the relay device status information 300 includes the traffic status and transmission time rate of each relay device 30 as a relay device.

[0059] The control unit 100 sets the priority of each relay device 30 based on the relay device status information 300. For example, the control unit 100 understands the congestion status of the relay devices 30 based on the available bandwidth and the number of connected terminals. The control unit 100 then lowers the priority of relay devices 30 with limited wireless resources. As another example, if there are transmission time rate constraints for downlink traffic from the relay device 30 to the wireless terminal 10, the control unit 100 understands the current status of downlink traffic and transmission time rate. The control unit 100 then lowers the priority of relay devices 30 with limited transmission time rate. Finally, the control unit 100 selects the relay device 30 to which the wireless module 11 will connect, according to the priority of each relay device 30.

[0060] A second processing example will be described with reference to Figures 9 and 10. In the example shown in Figures 9 and 10, the base station 20 is connected to the first relay device 30-1, the second relay device 30-2, and the third relay device 30-3.

[0061] The first wireless module 11-1 of the wireless terminal 10 sends a connection destination inquiry INQ to a nearby relay device 30. Upon receiving the connection destination inquiry INQ, each relay device 30 sends a connection destination inquiry notification NTF to the control unit 100. In response to the connection destination inquiry notification NTF, the control unit 100 selects a connection destination for the first wireless module 11-1 from among the relay devices 30 that are not connected to any other wireless module 11. At this time, the control unit 100 sets the priority of each relay device 30 based on the relay device status information 300 and selects a connection destination for the first wireless module 11-1 according to the priority. In this case, for example, the first relay device 30-1 has the highest priority and is selected. The control unit 100 instructs the selected first relay device 30-1 to respond to the first wireless module 11-1. Following the instructions from the control unit 100, the first relay device 30-1 returns a response RES to the first wireless module 11-1, which was the source of the connection destination inquiry. As a result, connection processing is performed between the first wireless module 11-1 and the first relay device 30-1.

[0062] Subsequently, the second wireless module 11-2 of the wireless terminal 10 sends a connection destination inquiry INQ to the surrounding relay devices 30. Upon receiving the connection destination inquiry INQ, each relay device 30 sends a connection destination inquiry notification NTF to the control unit 100. In response to the connection destination inquiry notification NTF, the control unit 100 selects a connection destination for the second wireless module 11-2 from among the relay devices 30 that are not connected to any other wireless module 11. At this time, the control unit 100 sets the priority of each relay device 30 based on the relay device status information 300 and selects a connection destination for the second wireless module 11-2 according to the priority. In this case, for example, the second relay device 30-2 has the highest priority and is selected. The control unit 100 instructs the selected second relay device 30-2 to respond to the second wireless module 11-2. Following the instructions from the control unit 100, the second relay device 30-2 returns a response RES to the second wireless module 11-2, which was the source of the connection destination inquiry. As a result, connection processing is performed between the second wireless module 11-2 and the second relay device 30-2.

[0063] Figure 11 is a flowchart showing a second example of processing by the control unit 100 included in the base station 20.

[0064] In step S120, the control unit 100 determines whether it has received a destination inquiry notification NTF from at least one relay device 30. The destination inquiry notification NTF is a notification indicating that the relay device 30 has received a destination inquiry INQ from the wireless module 11. If the destination inquiry notification NTF is received (step S120; Yes), the process proceeds to step S121.

[0065] In step S121, the control unit 100 sets the priority of each relay device 30 based on the relay device status information 300. Then, based on the priority of each relay device 30, the control unit 100 selects one relay device 30 to which the wireless module 11 will be connected.

[0066] In step S122, the control unit 100 instructs the selected relay device 30 to respond to the wireless module 11 that is the source of the connection inquiry.

[0067] As described above, according to the second processing example, it is possible to appropriately select the connection destination of the wireless module 11 according to the state of the relay device 30 (traffic, transmission time rate, etc.). By combining the first and second processing examples described above, it is possible to further improve throughput efficiently.

[0068] 3-3. Third Processing Example Figure 12 is a conceptual diagram illustrating a third processing example by the control unit 100 included in the base station 20. In the third processing example, the control unit 100 determines at least one of the channels used and the transmission power of each relay device 30.

[0069] More specifically, the control unit 100 constantly monitors the status of each of the multiple relay devices 30 connected to each of the multiple wireless modules 11 and updates the relay device status information 300 (see Figure 4). For example, the relay device status information 300 includes information on the wireless terminals 10 and wireless modules 11 under each relay device 30. As another example, the relay device status information 300 includes the distance between each relay device 30 and the wireless terminals 10 under it. As yet another example, the relay device status information 300 includes the traffic status and channels used for each relay device 30.

[0070] The control unit 100 determines at least one of the channel used and the transmission power of each relay device 30 based on the relay device status information 300. For example, the control unit 100 increases the transmission power of the relay device 30 as the distance between the relay device 30 and the wireless terminal 10 under its control increases. As another example, the control unit 100 may determine the channel used for each relay device 30 so that the channels used do not overlap among multiple relay devices 30. As yet another example, the control unit 100 may determine the channel used for each relay device 30 based on the communication status and communication quality between the base station 20 and each relay device 30.

[0071] The control unit 100 instructs each relay device 30 to operate according to the determined channel / transmission power. More specifically, the control unit 100 generates relay device control information CON indicating the determined channel / transmission power for each relay device 30. The control unit 100 then notifies each relay device 30 of the relay device control information CON. Each relay device 30 operates according to the channel / transmission power indicated in the relay device control information CON.

[0072] For example, the control unit 100 generates first relay device control information CON-1 indicating the channel / transmission power used, which has been determined for the first relay device 30-1. The control unit 100 then notifies the first relay device 30-1 of the first relay device control information CON-1. The first relay device 30-1 operates according to the channel / transmission power used, as indicated in the first relay device control information CON-1. The same applies to the second relay device 30-2.

[0073] Figure 13 is a flowchart showing a third processing example by the control unit 100 included in the base station 20.

[0074] In step S130, the control unit 100 determines whether or not it has received a connection status update notification from any of the relay devices 30. A connection status update notification is a notification indicating that the connection status between the relay device 30 and the wireless terminal 10 (wireless module 11) has been updated. If a connection status update notification is received (step S130; Yes), the process proceeds to step S131.

[0075] In step S131, the control unit 100 determines at least one of the channels used and the transmission power of the relay device 30 based on the relay device status information 300.

[0076] In step S132, the control unit 100 instructs the relay device 30 to operate according to the determined channel / transmission power.

[0077] According to the third processing example, communication quality can be improved by controlling the transmission power and channels used by the relay device 30.

[0078] 3-4. Fourth Processing Example It is also possible to combine two or more of the first to third processing examples described above. For example, a combination of the first, second, and third processing examples is also possible. [Explanation of symbols]

[0079] 1…Wireless communication system, 10…Wireless terminal, 11…Wireless module 11, 11-1…First wireless module, 11-2…Second wireless module, 11S…Module in use, 12…Upper layer, 13…Selector, 20…Base station, 30…Relay device, 30-1…First relay device, 30-2…Second relay device, 100…Control unit, 110…Processor, 120…Storage device, 130…Control program, 200…Module switching management information, 300…Relay device status information, CON…Relay device control information, INQ…Connection destination inquiry, NTF…Connection destination inquiry notification, PA…Transmission permission period, PB…Transmission prohibition period, SKD…Schedule information

Claims

1. A wireless terminal equipped with multiple wireless modules that perform wireless communication on different channels, A base station that performs wireless communication with the aforementioned multiple wireless modules, A plurality of relay devices that relay the wireless communication between each of the plurality of wireless modules and the base station. Equipped with, The wireless terminal uses one of the plurality of wireless modules as the active module and stops transmitting data from wireless modules other than the active module. The total transmission time per unit of time is limited for each channel. The aforementioned base station is The usage schedule for each of the multiple wireless modules of the wireless terminal is determined so that the transmission time rate of each of the multiple wireless modules does not exceed a predetermined upper limit. The information regarding the usage schedule is notified to the wireless terminal. It is configured in such a way, Each of the plurality of wireless modules of the wireless terminal operates as the usage module according to the usage schedule determined by the base station. Wireless communication system.

2. A wireless communication system according to claim 1, The plurality of wireless modules include a first wireless module, The plurality of relay devices include a first relay device connected to the first wireless module. The base station determines the usage schedule for the first wireless module and notifies the first wireless module of the usage schedule information for the first wireless module via the first relay device. The first wireless module operates as the usage module according to the usage schedule for the first wireless module, The first relay device relays the wireless communication between the base station and the first wireless module. Wireless communication system.

3. A wireless communication system according to claim 2, The usage schedule for the first wireless module includes a transmission permission period during which the first wireless module operates as the usage module. The first wireless module operates as the module in use during the transmission permission period determined by the base station. Wireless communication system.

4. A wireless communication system according to claim 1, The plurality of wireless modules include a first wireless module, The aforementioned base station further, The system maintains relay device status information indicating the status of each relay device connected to the base station, When a connection destination inquiry is received from the first wireless module, the first relay device is selected as the connection destination of the first wireless module based on the relay device status information. The selected first relay device is instructed to respond to the first wireless module. It is configured in such a way, The first wireless module connects to the first relay device selected by the base station. Wireless communication system.

5. A wireless communication system according to claim 1, The aforementioned base station further, The system maintains relay device status information indicating the status of each of the aforementioned multiple relay devices, Based on the relay device status information, at least one of the channels used and the transmission power of each of the plurality of relay devices is determined. Each relay device is instructed to operate according to at least one of the determined channel used and the transmission power. It is configured in such a way Wireless communication system.

6. A wireless communication control method for controlling wireless communication between a wireless terminal and a base station via multiple relay devices, The wireless terminal comprises multiple wireless modules that perform wireless communication on different channels, uses one of the multiple wireless modules as the active module, and stops data transmission from the wireless modules other than the active module. The plurality of relay devices relay the wireless communication between each of the plurality of wireless modules and the base station. The total transmission time per unit of time is limited for each channel. The wireless communication control method is, In the base station, the usage schedule for each of the multiple wireless modules of the wireless terminal is determined so that the transmission time rate of each of the multiple wireless modules does not exceed a predetermined upper limit. The information of the aforementioned usage schedule is notified from the base station to the wireless terminal, In accordance with the usage schedule determined by the base station, each of the plurality of wireless modules of the wireless terminal is operated as the module being used. including Wireless communication control method.

7. A base station that communicates wirelessly with wireless terminals via multiple relay devices, The wireless terminal comprises multiple wireless modules that perform wireless communication on different channels, uses one of the multiple wireless modules as the active module, and stops data transmission from the wireless modules other than the active module. The plurality of relay devices relay the wireless communication between each of the plurality of wireless modules and the base station. The total transmission time per unit of time is limited for each channel. The base station includes a control unit, The control unit, The usage schedule for each of the multiple wireless modules of the wireless terminal is determined so that the transmission time rate of each of the multiple wireless modules does not exceed a predetermined upper limit. The information of the usage schedule is notified to the wireless terminal, and each of the plurality of wireless modules of the wireless terminal is made to operate as the usage module according to the usage schedule. It is configured in such a way Base station.

8. A base station according to claim 7, The plurality of wireless modules include a first wireless module, The control unit further, The system maintains relay device status information indicating the status of each relay device connected to the base station, In response to a connection destination inquiry from the first wireless module to each of the relay devices, the first relay device is selected as the connection destination of the first wireless module based on the relay device status information. The selected first relay device is instructed to respond to the first wireless module. It is configured in such a way Base station.

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