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

Abstract

This wireless communication system is provided with multiple wireless communication devices that configure a wireless communication network, and one or multiple controllers that control the multiple wireless communication devices. Each of the wireless communication devices is provided with multiple network interface controllers (NICs) which perform wireless communication with mutually different, non-overlapping channels. The one or multiple controllers perform channel switching processing for switching the use state of the multiple NICs in each of the multiple wireless communication devices. The one or multiple controllers perform control such that the multiple wireless communication devices use NICs with the same channel in the same period.

Description

[Technical field]

[0001] The present disclosure relates to a technique for controlling a wireless communication system that performs wireless communication by switching between multiple channels. [Background technology]

[0002] A wireless communication system consisting of a base station and a wireless terminal is known. A typical example of a wireless communication system is a public wireless LAN (Local Area Network). In a public wireless LAN, for example, a use case is assumed in which data is transmitted from a base station to a wireless terminal such as a computer terminal or a smartphone terminal. Furthermore, with the recent spread of IoT (Internet of Things) terminals, the use cases in which data is transmitted from a wireless terminal to a base station are increasing.

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

[0004] Since the number of frequency channels in the 920 MHz band is limited, it is conceivable that wireless communication may be carried out while changing the channel in use.

[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 limit data transmission to comply with this total transmission time limit, so throughput is also limited. However, for wireless communication device housings that switch between two non-overlapping channels, a total transmission time of 360 seconds per hour for each channel is allowed, for a total of 720 seconds. Therefore, in order to improve throughput, it is conceivable to perform wireless communication while changing the channel used by the wireless communication device housing. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] "Standard for 920MHz Band Radio Equipment for Telemetry, Telecontrol and Data Transmission", Association of Radio Industries and Businesses, ARIB STD-T108 Version 1.3, April 12, 2019 [Non-Patent Document 2] “IEEE Standard for Information technology - Telecommunications and information exchange between systems Local and metropolitan area networks - Specific requirements, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Amendment 2: Sub 1 GHz License Exempt Operation,” IEEE Computer Society, IEEE Std 802.11ah TM-2016, 7 December 2016. Summary of the Invention [Problem to be solved by the invention]

[0007] When wireless communication is performed by switching between multiple channels, it is often necessary to restart the wireless communication device when switching channels. Packet loss or communication interruption during the restart of the wireless communication device leads to degradation of service quality.

[0008] An object of the present disclosure is to provide a technique that enables wireless communication by switching between multiple channels without rebooting a wireless communication device. [Means for solving the problem]

[0009] The first aspect relates to a wireless communication system. The wireless communication system includes: A plurality of wireless communication devices constituting a wireless communication network; One or more control devices for controlling a plurality of wireless communication devices; Equipped with. Each of the plurality of wireless communication devices includes a plurality of network interface controllers that perform wireless communication on different non-overlapping channels. The one or more control devices execute a channel switching process for switching the usage states of the multiple network interface controllers in each of the multiple wireless communication devices. The one or more control devices control the multiple wireless communication devices to use the same channel network interface controller for the same period of time.

[0010] The second aspect relates to a wireless communication control method for controlling a plurality of wireless communication devices that configure a wireless communication network. Each of the plurality of wireless communication devices includes a plurality of network interface controllers that perform wireless communication on different non-overlapping channels. The wireless communication control method includes: a channel switching process for switching the usage states of a plurality of network interface controllers in each of a plurality of wireless communication devices; A process of controlling a plurality of wireless communication devices to use the same channel network interface controller for the same period. Includes.

[0011] The third aspect relates to a control device that controls a plurality of wireless communication devices that configure a wireless communication network. Each of the plurality of wireless communication devices includes a plurality of network interface controllers that perform wireless communication on different non-overlapping channels. The control device includes a processor. The processor executes a channel switching process for switching the usage states of a plurality of network interface controllers in each of a plurality of wireless communication devices. The processor controls the wireless communication devices to use the same channel network interface controller for the same period of time.

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

[0013] According to the present disclosure, it is possible to switch between multiple channels and perform wireless communication without rebooting the wireless communication device. Since rebooting the wireless communication device is not required, the time required for channel switching, i.e., the time required to resume communication, is shortened. This reduces packet loss and communication interruption time, and increases throughput. In addition, degradation of service quality is also prevented. [Brief description of the drawings]

[0014] [Figure 1] 1 is a block diagram illustrating a schematic configuration example of a wireless communication system according to an embodiment of the present disclosure. [Diagram 2]1 is a conceptual diagram for explaining an example of a channel switching process (NIC switching process) in a wireless communication system according to an embodiment of the present disclosure. [Diagram 3] 1 is a block diagram illustrating a configuration example of a wireless communication device according to an embodiment of the present disclosure. [Figure 4] 1 is a block diagram showing a configuration example of a control device according to an embodiment of the present disclosure. [Diagram 5] 1 is a flowchart for explaining a first example of a channel switching process (NIC switching process) according to an embodiment of the present disclosure. [Figure 6] 1 is a flowchart for explaining a first example of a channel switching process (NIC switching process) according to an embodiment of the present disclosure. [Figure 7] 11 is a flowchart for explaining a second example of a channel switching process (NIC switching process) according to an embodiment of the present disclosure. [Figure 8] 11 is a flowchart for explaining a second example of a channel switching process (NIC switching process) according to an embodiment of the present disclosure. [Figure 9] 13 is a flowchart for explaining a third example of a channel switching process (NIC switching process) according to an embodiment of the present disclosure. [Figure 10] 13 is a flowchart for explaining a third example of a channel switching process (NIC switching process) according to an embodiment of the present disclosure. [Figure 11] 13 is a flowchart illustrating a fourth example of a channel switching process (NIC switching process) according to an embodiment of the present disclosure. [Figure 12] 13 is a flowchart illustrating a fourth example of a channel switching process (NIC switching process) according to an embodiment of the present disclosure. [Figure 13] 13 is a flowchart illustrating a fifth example of a channel switching process (NIC switching process) according to an embodiment of the present disclosure. [Figure 14] 13 is a flowchart illustrating a fifth example of a channel switching process (NIC switching process) according to an embodiment of the present disclosure. [Figure 15]11 is a flowchart illustrating an example of a connection information sharing process in the wireless communication system according to the embodiment of the present disclosure. [Figure 16] 11 is a flowchart showing a general connection process. [Figure 17] 10 is a flowchart illustrating an example of a connection process according to an embodiment of the present disclosure. [Figure 18] FIG. 11 is a block diagram illustrating a schematic configuration example of a wireless communication system according to an embodiment of the present disclosure. [Figure 19] 1 is a conceptual diagram for explaining an example of a channel switching process (NIC switching process) and a limited communication process in a wireless communication system according to an embodiment of the present disclosure. [Figure 20] 11 is a flowchart illustrating a limited communication process according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0016] 1. Overview of wireless communication systems 1 is a block diagram showing a schematic configuration example of a wireless communication system 1 according to the present embodiment. The wireless communication system 1 includes a plurality of wireless communication devices 10 that form a wireless communication network.

[0017] For example, the multiple wireless communication devices 10 include a base station (parent device) and one or more wireless terminals. The base station and one or more wireless terminals form 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 is an access point of the wireless LAN. A cell consisting of an access point and one or more wireless terminals is called a BSS (Basic Service Set). For simplicity, in the following description, the base station is called an "AP" and the wireless terminal is called an "STA."

[0018] The wireless communication system 1 performs wireless communication, for example, using the unlicensed Sub-1 GHz band. For example, the wireless communication system 1 performs wireless communication, for example, using the 920 MHz band.

[0019] The wireless communication system 1 according to the present embodiment can perform wireless communication by switching between multiple channels (frequency channels). That is, the wireless communication device 10 can perform wireless communication by switching between multiple channels. The process of switching the channel used by the wireless communication device 10 is hereinafter referred to as a "channel switching process."

[0020] According to this embodiment, multiple network interface controllers (network interface cards) are used for channel switching processing. In the following description, for simplicity, the network interface controller is called "NIC." To distinguish between multiple NICs, a subnumber such as "NIC-i" is used.

[0021] In the example shown in FIG. 1, each wireless communication device 10 (AP, STA) includes a plurality of NIC-1 to NIC-N. Here, N is an integer equal to or greater than 2. For example, N is 2. The plurality of NIC-1 to NIC-N are set to perform wireless communication on different channels CH-1 to CH-N that do not overlap with each other. Therefore, by switching the usage state of the plurality of NIC-1 to NIC-N, the channel used for wireless communication can be switched. In other words, by switching the NIC to be used among the plurality of NIC-1 to NIC-N, the channel used for wireless communication can be switched. The NIC selectively used among the plurality of NIC-1 to NIC-N is hereinafter referred to as a "selected NIC". The "selected NIC" can also be referred to as a "used NIC", an "active NIC", etc. The channel switching process can also be said to be a "NIC switching process" that switches the selected NIC among the plurality of NIC-1 to NIC-N.

[0022] The wireless communication system 1 according to the present embodiment further includes one or more control devices 100 that control the multiple wireless communication devices 10 (AP, STA). In particular, the one or more control devices 100 manage and control the above-mentioned channel switching process (NIC switching process).

[0023] 1, a plurality of control devices 100 are connected to a plurality of wireless communication devices 10, respectively. For example, the plurality of control devices 100 control the plurality of wireless communication devices 10, respectively, in synchronization with each other. In addition, not only the plurality of control devices 100 control the plurality of wireless communication devices 10, but also a single control device 100 can control all of the plurality of wireless communication devices 10. For example, the control device 100 connected to an AP may control the AP and each STA.

[0024] The control device 100 does not necessarily need to be connected to the outside of the wireless communication device 10. The function of the control device 100 may be included in each wireless communication device 10. For example, the function of the control device 100 is realized by each wireless communication device 10 executing a control program. In this case, the wireless communication device 10 that executes the control program corresponds to the control device 100.

[0025] In the following description, one or more control devices 100 and control programs that manage and control the channel switching process are collectively referred to as the "control device 100" or a "control function."

[0026] The control device 100 (control function) according to this embodiment executes a channel switching process for switching the usage state of the multiple NIC-1 to NIC-N in each of the multiple wireless communication devices 10. In other words, the control device 100 (control function) executes a channel switching process for switching the selected NIC in each of the multiple wireless communication devices 10 among the multiple NIC-1 to NIC-N. Furthermore, the control device 100 collectively controls the multiple wireless communication devices 10 so that the multiple wireless communication devices 10 use the selected NIC of the same channel for the same period of time. By collectively controlling the multiple wireless communication devices 10, it is possible to efficiently execute the channel switching process.

[0027] 2 is a conceptual diagram for explaining an example of a channel switching process (NIC switching process) according to the present embodiment. The AP includes a NIC-1 that performs wireless communication on a first channel CH-1, and a NIC-2 that performs wireless communication on a second channel CH-2 different from the first channel CH-1. Similarly, the STA includes a NIC-1 that performs wireless communication on the first channel CH-1, and a NIC-2 that performs wireless communication on the second channel CH-2 different from the first channel CH-1.

[0028] In a first period from time t1s to time t1e, the control device 100 sets the first mode. Specifically, the control device 100 sets NIC-1 as the selected NIC in each of the AP and the STA. The AP and the STA configure a BSS-1, and both perform wireless communication using the NIC-1. Furthermore, the control device 100 basically prohibits data transmission using a NIC-2 other than the selected NIC (NIC-1) in each of the AP and the STA. In other words, the first period from time t1s to time t1e is a "transmission prohibition period" for the NIC-2 other than the selected NIC. During the transmission prohibition period, data reception is possible, but data transmission is prohibited. As a modified example, even during the transmission prohibition period, only transmission of a specific wireless frame (for example, a response frame (ACK) in response to reception of an uplink frame) may be permitted.

[0029] In a second period from time t2s to time t2e, the control device 100 sets the second mode. Specifically, the control device 100 sets NIC-2 as the selected NIC in each of the AP and the STA. The AP and the STA configure BSS-2, and both perform wireless communication using NIC-2. Furthermore, the control device 100 basically prohibits data transmission using NIC-1 other than the selected NIC (NIC-2) in each of the AP and the STA. In other words, the second period from time t2s to time t2e is a "transmission prohibition period" for NIC-1 other than the selected NIC. During the transmission prohibition period, data reception is possible, but data transmission is prohibited. As a modified example, even during the transmission prohibition period, only transmission of a specific wireless frame (for example, a response frame (ACK) in response to reception of an uplink frame) may be permitted.

[0030] During the period between the first mode and the second mode (time t1e to time t2s), module switching and the like are performed.

[0031] The control device 100 alternates between the first mode and the second mode, thereby switching the selected NIC (channel to be used). In other words, the control device 100 switches between NIC-1 and NIC-2 so that their data transmission times do not overlap. It can also be said that the control device 100 switches between BSS-1 and BSS-2 so that their data transmission times do not overlap.

[0032] As described above, according to this embodiment, each of the multiple wireless communication devices 10 includes multiple NIC-1 to NIC-N that perform wireless communication on different non-overlapping channels. The control device 100 executes a channel switching process that switches the selected NIC in each wireless communication device 10 between the multiple NIC-1 to NIC-N. Furthermore, the control device 100 controls the multiple wireless communication devices 10 to use the selected NICs of the same channel for the same period of time.

[0033] Switching between NICs does not require rebooting the wireless communication device 10. Therefore, wireless communication can be performed by switching between multiple channels without rebooting the wireless communication device 10. Since rebooting the wireless communication device 10 is not required, the time required for channel switching, i.e., the time required to resume communication, is shortened. This reduces packet loss and communication interruption time, and increases throughput. Also, degradation of service quality is prevented.

[0034] For communication between upper layers, it is possible to apply a virtualization technology for multiple communication paths, such as multipath TCP, to multiple NICs. This makes it possible to compensate for packet loss at the transport layer and maintain quality of service.

[0035] 2. Configuration Example 3 is a block diagram showing a configuration example of a wireless communication device 10 (AP, STA) according to the present embodiment. The wireless communication device 10 includes one or more processors 11, one or more storage devices 12, a wired NIC, and multiple wireless NICs (NIC-1 to NIC-N).

[0036] The processor 11 performs various information processing. For example, the processor 11 includes a CPU (Central Processing Unit). The storage device 12 stores various information required for processing by the processor 11. Examples of the storage device 12 include a volatile memory, a non-volatile memory, an HDD (Hard Disk Drive), and an SSD (Solid State Drive).

[0037] The control program 13 is a computer program executed by the processor 11 (computer). The processor 11 executes the control program 13 to realize the functions of the wireless communication device 10. The control program 13 is stored in the storage device 12. The control program 13 may be recorded in a computer-readable recording medium. The control program 13 may be provided to the wireless communication device 10 via a network. The processor 11 that executes the control program 13 corresponds to the control device 100 that controls the wireless communication device 10.

[0038] The management information 14 includes at least information used for managing and controlling the above-mentioned channel switching process. For example, the management information 14 includes a network identifier (BSSID), a channel, a switching timing, and the like for each NIC. The management information 14 may also include a total transmission time for each NIC. The management information 14 is stored in the storage device 12.

[0039] Furthermore, the wireless communication device 10 may include an interface 15 for operating from an external device. For example, the interface 15 is connected to an external control device 100. The interface 15 may include a user interface.

[0040] Furthermore, the wireless communication device 10 may include a timer 16 for managing the timing of channel switching (NIC switching).

[0041] 4 is a block diagram showing an example of the configuration of the control device 100 according to this embodiment. The control device 100 includes one or more processors 110 and one or more storage devices 120.

[0042] The processor 110 performs various types of information processing. For example, the processor 110 includes a CPU. The storage device 120 stores various types of information required for processing by the processor 110. Examples of the storage device 120 include a volatile memory, a non-volatile memory, a HDD, and an SSD.

[0043] The control program 130 is a computer program executed by the processor 110 (computer). The processor 110 executes the control program 130 to realize the functions of the control device 100. The control program 130 is stored in the storage device 120. The control program 130 may be recorded in a computer-readable recording medium. The control program 130 may be provided to the control device 100 via a network.

[0044] The management information 140 includes information used for managing and controlling the above-mentioned channel switching process. For example, the management information 140 includes a network identifier (BSSID), a channel, a switching timing, and the like, for each NIC of each wireless communication device 10. The management information 140 may include a total transmission time for each NIC. The management information 140 is stored in the storage device 120.

[0045] Furthermore, the control device 100 may include an interface 150. For example, the interface 150 is connected to the wireless communication device 10. The interface 150 may include a user interface.

[0046] Furthermore, the control device 100 may include a timer 160 for managing the timing of channel switching (NIC switching).

[0047] 3. Various examples of channel switching processing Various examples of the channel switching process (NIC switching process) according to the present embodiment will be described below.

[0048] 3-1. First Example In a first example of the channel switching process, the control device 100 controls each wireless communication device 10 (AP, STA) to stop packet transfer from the upper layer to a NIC other than the selected NIC. Hereinafter, the first example of the channel switching process will be described with reference to Figs. 5 and 6.

[0049] FIG. 5 shows a process flow by the control device 100 (control function).

[0050] In step S110, the control device 100 (for example, the control device 100 on the AP side) recognizes the NIC switching timing based on the management information 140. At the NIC switching timing, the control device 100 transmits a NIC switching instruction (channel switching instruction) to the AP and each STA. The NIC switching instruction at least instructs to stop packet transfer to the "NIC to be suspended." Here, the NIC to be suspended is the selected NIC that was used before the NIC switching timing, and enters a transmission prohibition period after the NIC switching timing.

[0051] In step S111, the control device 100 determines whether or not responses to the NIC switching instruction have been received from all of the wireless communication devices 10. In step S112, the control device 100 retransmits the NIC switching instruction to the wireless communication devices 10 from which the control device 100 has not yet received a response.

[0052] If there are a large number of STAs, the NIC switching instruction may be issued in advance, taking into consideration the time required to complete the instruction (notification) to all STAs. Alternatively, if there are a large number of STAs, the NIC switching timing may be determined in advance, and the NIC switching timing may be notified in advance when the BSS is started up.

[0053] FIG. 6 shows a process flow by each wireless communication device 10 (AP, STA).

[0054] In step S10, the wireless communication device 10 receives a NIC switching instruction from the control device 100. In response to the NIC switching instruction, the wireless communication device 10 stops packet transfer from an upper layer to the NIC to be suspended. Here, the upper layer is a layer higher than the NIC, and examples of the upper layer include a transport layer and an application layer. By controlling the destination from such an upper layer, packet transfer to the NIC to be suspended can be stopped. As another example, a function of controlling time fairness provided in the wireless LAN controller may be applied to limit packets assigned to the NIC to be suspended.

[0055] In step S11, the AP stops the transmission of beacon frames from the NIC to be suspended. Usually, beacon frames are transmitted even when there is no packet transfer from an upper layer. In this example, during the transmission prohibition period, the transmission of such beacon frames is also stopped. For example, the setting value of the beacon transmission interval is set to a sufficiently large value.

[0056] In step S12, the wireless communication device 10 returns a response to the control device 100.

[0057] In step S13, the wireless communication device 10 waits for a set time to transmit packets remaining in the transmission queue of the wireless module of the NIC to be suspended. For example, if the transmission queue has a capacity of 200 packets and the transmission time of one packet is 10 ms, the waiting time is set to 2 seconds. If the amount of remaining packets is less than the transmission queue capacity, the waiting time may be set to a shorter time.

[0058] However, if all STAs wait for packet communication by some STAs, the overall communication efficiency decreases. Also, it is difficult to accurately grasp the status in the transmission queue in real time. Therefore, after the set time has elapsed, the wireless communication device 10 discards the remaining packets in the transmission queue of the NIC to be suspended (step S14).

[0059] In step S15, the wireless communication device 10 starts transferring packets from the upper layer to the selected NIC that will be used next, and then the wireless communication device 10 starts communication using the selected NIC.

[0060] The STA maintains the state in which it was initially associated with the AP. To achieve this, the STA sets the BSSMaxIdlePeriod (the time during which the connection does not time out due to the absence of the BSS) to a time that is sufficiently longer than the transmission prohibition period. For example, if NIC switching is performed once every 30 minutes, a sufficiently long time is several hours. This allows the connection with the AP to be maintained even if there is no communication in the BSS for a long period of time. If channel switching is not performed periodically, the BSSMaxIdlePeriod may be set to a long period (for example, several years). IEEE 802.11ah has a USF (Unified Scaling Factor), which makes it possible to maintain the connection for a long period (up to several years).

[0061] 3-2. Second Example In a second example of the channel switching process, the control device 100 controls each wireless communication device 10 (AP, STA) to stop the operation of NICs other than the selected NIC. Hereinafter, the second example of the channel switching process will be described with reference to Figs. 7 and 8.

[0062] FIG. 7 shows a process flow by the control device 100 (control function).

[0063] In step S120, the control device 100 (for example, the control device 100 on the AP side) recognizes the NIC switching timing based on the management information 140. At the NIC switching timing, the control device 100 transmits a NIC switching instruction (channel switching instruction) to the AP and each STA. This step S120 is similar to step S110 in the first example.

[0064] In step S121, the control device 100 determines whether or not responses to the NIC switching instruction have been received from all of the wireless communication devices 10. In step S122, the control device 100 retransmits the NIC switching instruction to the wireless communication devices 10 from which the control device 100 has not yet received a response.

[0065] FIG. 8 shows a process flow by each wireless communication device 10 (AP, STA).

[0066] In step S20, the wireless communication device 10 receives an NIC switching instruction from the control device 100. In response to the NIC switching instruction, the wireless communication device 10 stops packet transfer from the upper layer to the NIC to be suspended. This step S20 is similar to step S10 in the first example.

[0067] In step S21, the wireless communication device 10 returns a response to the control device 100.

[0068] In step S22, the wireless communication device 10 waits for a set time to transmit packets remaining in the transmission queue of the wireless module of the NIC to be suspended. This step S22 is similar to step S13 in the first example.

[0069] After the set time has elapsed, the wireless communication device 10 stops the operation of the NIC to be suspended (step S23). The suspended state may be a temporary sleep state or a completely OFF state.

[0070] In step S24, the wireless communication device 10 activates the NIC that is to be used next. The activated NIC is the selected NIC.

[0071] In step S25, the AP and the STA perform connection processing with each other on the new channel. Then, the AP and the STA start packet transfer from the upper layer to the selected NIC, and start communication using the selected NIC.

[0072] 3-3.Third Example The third example of the channel switching process is a modified example of the second example. In the third example, the timing of connecting to the next channel is explicitly specified. Hereinafter, the third example of the channel switching process will be described with reference to Figs. 9 and 10.

[0073] FIG. 9 shows a process flow by the control device 100 (control function).

[0074] In step S130, the control device 100 (e.g., the control device 100 on the AP side) recognizes the NIC switching timing based on the management information 140. At the NIC switching timing, the control device 100 transmits an NIC switching instruction (channel switching instruction) to the AP and each STA. Furthermore, the control device 100 notifies the AP and each STA of a schedule of the timing of connection to the next channel.

[0075] In step S131, the control device 100 determines whether or not responses to the NIC switching instruction have been received from all of the wireless communication devices 10. In step S132, the control device 100 retransmits the NIC switching instruction to the wireless communication devices 10 from which the control device 100 has not yet received a response.

[0076] FIG. 10 shows a process flow by each wireless communication device 10 (AP, STA).

[0077] In step S30, the wireless communication device 10 receives an NIC switching instruction from the control device 100. In response to the NIC switching instruction, the wireless communication device 10 stops packet transfer from the upper layer to the NIC to be suspended. This step S20 is similar to step S10 in the first example.

[0078] In step S31, the wireless communication device 10 returns a response to the control device 100.

[0079] In step S32, the wireless communication device 10 waits for a set time to transmit packets remaining in the transmission queue of the wireless module of the NIC to be suspended. This step S32 is similar to step S13 in the first example.

[0080] After the set time has elapsed, the wireless communication device 10 stops the operation of the NIC to be suspended (step S33). The suspended state may be a temporary sleep state or a completely OFF state.

[0081] In step S34, the wireless communication device 10 activates the NIC that is to be used next. The activated NIC is the selected NIC. At this time, the AP activates the NIC that is to be used next in stealth mode. In stealth mode, the AP does not notify its BSSID to the surrounding area in a beacon frame. By using stealth mode, it is possible to reduce collisions between frames and to avoid connections from unscheduled STAs.

[0082] In step S35, the STA starts a process of connecting to the AP at the connection timing notified by the control device 100.

[0083] When all scheduled connection processes are completed, the AP releases the stealth mode, and the AP and STA start forwarding packets from the upper layer to the selected NIC, and start communication using the selected NIC (step S36).

[0084] 3-4. Fourth Example In the fourth example of the channel switching process, TWT (Target Wake Time) is used. TWT is a technology in which a sleep period is negotiated in advance between the AP and the STA, and communication is stopped during the sleep period, which is expected to save power and avoid frame collisions. The control device 100 can control each wireless communication device 10 (AP, STA) to set a sleep period (transmission prohibition period) for NICs other than the selected NIC based on the TWT.

[0085] There are two types of TWT: Implicit TWT and Explicit TWT. Implicit TWT is a method in which the schedule is determined in advance. On the other hand, Explicit TWT is a method in which the schedule is notified each time. In the fourth example, Implicit TWT is used. Hereinafter, the fourth example of the channel switching process will be described with reference to Figs. 11 and 12.

[0086] FIG. 11 shows a process flow by the control device 100 (control function).

[0087] When the AP is started, the control device 100 (e.g., the control device 100 on the AP side) determines the sleep period for the NIC of each channel based on a predetermined channel switching schedule (step S140). Then, the control device 100 notifies the AP of the determined sleep period for each NIC (step S141).

[0088] FIG. 12 shows a process flow by each wireless communication device 10 (AP, STA).

[0089] In step S40, the AP sets the Implicit TWT period so that the transmission times of the channels (NICs) do not overlap, based on the notification received from the control device 100. The AP also notifies each STA of the Implicit TWT period. The notification method of the TWT period (negotiation method between the AP and the STA) can be negotiation for each individual terminal or negotiation by broadcast, and either of the available methods is used.

[0090] In step S41, each STA sets an Implicit TWT period for the NIC of each channel based on the notification received from the AP.

[0091] In step S42, the AP sets the NIC that is going into the sleep period to stop transmitting beacon frames, for example, by setting the beacon transmission interval to a sufficiently large value.

[0092] In step S43, the AP sets the STA to return a rejection response if the STA mistakenly sends a transmission request during the sleep period.

[0093] The available functions are not limited to TWT. Other sleep functions or access restriction functions such as RAW (Restricted Access Window) may be used. In general, the control device 100 controls each wireless communication device 10 (AP, STA) to set a transmission prohibition period for NICs other than the selected NIC based on the sleep function or access restriction function of the wireless communication system 1.

[0094] 3-5. Fifth Example In a fifth example of the channel switching process, Explicit TWT is used. Hereinafter, the fifth example of the channel switching process will be described with reference to Figs.

[0095] FIG. 13 shows a process flow by the control device 100 (control function).

[0096] In step S150, the control device 100 (e.g., the control device 100 on the AP side) recognizes the NIC switching timing based on the management information 140. At the NIC switching timing, the control device 100 transmits a NIC switching instruction (channel switching instruction) to the AP and each STA. Furthermore, the control device 100 determines the sleep period of the NIC to be suspended, and notifies the AP of the sleep period of the NIC to be suspended.

[0097] In step S151, the control device 100 determines whether or not responses to the NIC switching instruction have been received from all of the wireless communication devices 10. In step S152, the control device 100 retransmits the NIC switching instruction to the wireless communication devices 10 from which the control device 100 has not yet received a response.

[0098] FIG. 14 shows a process flow by each wireless communication device 10 (AP, STA).

[0099] In step S50, the wireless communication device 10 receives an NIC switching instruction from the control device 100. In response to the NIC switching instruction, the wireless communication device 10 stops packet transfer from the upper layer to the NIC to be suspended. This step S50 is similar to step S10 in the first example.

[0100] In step S51, the wireless communication device 10 returns a response to the control device 100.

[0101] In step S52, the AP sets the Explicit TWT period so that the transmission times of the channels (NICs) do not overlap, based on the notification received from the control device 100. The AP also notifies each STA of the Explicit TWT period. The method of notifying the TWT period (negotiation method between the AP and the STA) includes negotiation for each individual terminal and negotiation by broadcast, and any compatible method is used.

[0102] In step S53, each STA sets an Explicit TWT period for the NIC of each channel based on the notification received from the AP.

[0103] In step S54, the AP sets the NIC that is going into the sleep period to stop transmitting beacon frames, for example by setting the beacon transmission interval to a sufficiently large value.

[0104] In step S55, the AP sets the STA to return a rejection response if the STA mistakenly sends a transmission request during the sleep period.

[0105] 4. Reduction in connection processing time associated with channel switching A method for shortening the connection processing time involved in the channel switching process will be described below.

[0106] Prior to the channel switching process, the control device 100 controls the multiple wireless communication devices 10 to execute a "connection information sharing process." More specifically, the control device 100 controls the multiple wireless communication devices 10 to share connection information related to each of the multiple NICs in advance. For example, the connection information related to each NIC includes the switching timing of the NIC, a network identifier (e.g., BSSID), and an assigned channel. Then, the multiple wireless communication devices 10 execute a connection process to connect to each other via the selected NIC based on the previously acquired connection information.

[0107] In this way, the connection information for each NIC is shared before the channel switching process, so the time required for the connection process when switching channels is reduced. In particular, the time required for the connection process when a STA first connects to an AP and then performs channel switching for the first time is reduced. As a result, the time required for channel switching is reduced, and the service quality is improved.

[0108] FIG. 15 is a flowchart illustrating an example of the connection information sharing process.

[0109] Consider a new STA that connects to an AP for the first time. For a new STA that connects to an AP for the first time, a normal connection procedure is first performed (step S60). At this time, a NIC on the same channel as the selected NIC currently used by the AP is used as the selected NIC.

[0110] After the connection process is completed, the AP performs an inquiry communication with the new STA. During this inquiry communication, the AP acquires information on the NIC environment of the new STA (step S61). The NIC environment includes the number of NICs that the STA has. The NIC environment may also include whether the STA supports the channel switching process according to this embodiment. For example, if the STA can use general-purpose network commands such as embedded Linux (registered trademark), the NIC environment can be acquired by using a command such as ifconfig. As another example, the new STA may create information on its own NIC environment in response to an inquiry from the AP and return it to the AP.

[0111] In the next step S62, the AP judges whether the number of NICs of the new STA is equal to or greater than the number of NICs of the AP. In other words, the AP judges whether the number of NICs of the new STA is insufficient for the number of NICs of the AP. If the number of NICs of the new STA is equal to or greater than the number of NICs of the AP, that is, if the number of NICs of the new STA is not insufficient for the number of NICs of the AP (step S62; Yes), the process proceeds to step S63. On the other hand, if the number of NICs of the new STA is insufficient for the number of NICs of the AP (step S62; No), the process proceeds to step S64.

[0112] In step S63, the AP notifies the new STA of connection information related to each NIC included in the AP. For example, the connection information related to each NIC includes the switching timing of the NIC, a network identifier (e.g., BSSID), and an assigned channel.

[0113] In step S64, the AP transmits an error message to the control device 100 indicating that there is a shortage.

[0114] Incidentally, steps S62 and S64 may be omitted.

[0115] Fig. 16 shows a typical connection process as a comparative example. First, the STA scans all channels until it detects a beacon including the SSID of the connection destination AP (step S1). Then, the AP and the STA exchange Probe Request / Response frames (step S2), Association Request / Response frames (step S3), and Authentication Request / Response frames (step S4). Furthermore, to protect communications, the AP and the STA exchange security information using the Extensible Authentication Protocol (step S5). Then, an IP address is assigned using DHCP (Dynamic Host Configuration Protocol) to enable communications (step S6).

[0116] 17 is a flowchart showing an example of a connection process according to this embodiment. For example, if the connection information includes channel information of the NIC to be used next, channel scanning is not necessary, and step S1 can be omitted. Also, if the NIC is the same, exchange of Probe information is not necessary, and step S2 can be omitted. Step S5 can also be omitted by exchanging security information in advance.

[0117] By exchanging the contents of the Association Request / Response frames in advance, step S3 can be omitted, further speeding up the connection process.

[0118] 16, the transmission rate cannot be adjusted at the connection processing stage, so the lowest rate is used as the transmission speed of the wireless frame. On the other hand, according to this embodiment, the information transmission time in the connection processing can be shortened by notifying the optimal rate in advance.

[0119] As described above, according to the present embodiment, since the connection information regarding each NIC is shared before the channel switching process, the time required for the connection process during channel switching is shortened. In particular, after a certain STA first connects to an AP, the time required for the connection process when the channel switching process is first performed in that STA is shortened. As a result, the time required for channel switching is shortened, and the service quality is improved.

[0120] 5. Handling in a mixed environment Not all STAs can support the channel switching process (NIC switching process) according to the present embodiment. For example, when the number of NICs of a certain STA is insufficient compared to the number of NICs of the AP, that NIC may not always be able to keep up with the channel switching process.

[0121] A wireless terminal (first wireless terminal) that can fully support the channel switching process according to the present embodiment is hereinafter referred to as "STA-X". On the other hand, a wireless terminal (second wireless terminal) that cannot necessarily support the channel switching process according to the present embodiment is hereinafter referred to as "STA-Y". Hereinafter, the processing in the case where the wireless communication system 1 includes both STA-X and STA-Y in a mixed environment will be described.

[0122] FIG. 18 is a block diagram schematically showing a configuration example of the wireless communication system 1 in the case of a mixed environment. Descriptions overlapping with the above-mentioned FIG. 1 will be omitted as appropriate. The wireless communication system 1 includes a plurality of wireless communication devices 10 that constitute a wireless communication network. The plurality of wireless communication devices 10 include an AP, one or more STA-Xs, and one or more STA-Ys. The AP and STA-X are provided with NIC-1 to NIC-N. Here, N is an integer of 2 or more. On the other hand, STA-Y is provided with NIC-1 to NIC-M. Here, M is an integer less than N (M < N). For example, when N is 2 and M is 1, STA-X is a multi-channel wireless terminal, and STA-Y is a single-channel wireless terminal.

[0123] Fig. 19 is a conceptual diagram for explaining an example of channel switching processing in a mixed environment. Explanations that overlap with those in Fig. 2 will be omitted as appropriate. AP and STA-X are equipped with NIC-1 that performs wireless communication on a first channel CH-1, and NIC-2 that performs wireless communication on a second channel CH-2 different from the first channel CH-1. On the other hand, STA-Y is equipped with NIC-1 that performs wireless communication on the first channel CH-1, but is not equipped with NIC-2 that performs wireless communication on the second channel CH-2.

[0124] The above-mentioned channel switching process (see Sections 1 and 3) is performed for the AP and STA-X.

[0125] In a first period from time t1s to time t1e, the control device 100 sets the first mode. Specifically, the control device 100 sets NIC-1 as the selected NIC in each of the AP and STA-X. NIC-2 enters a transmission prohibited period.

[0126] In a second period from time t2s to time t2e, the control device 100 sets the second mode. Specifically, the control device 100 sets NIC-2 as the selected NIC in each of the AP and STA-X. NIC-1 enters a transmission prohibited period.

[0127] During the transmission inhibition period, data reception is possible but data transmission is prohibited. As a modified example, even during the transmission inhibition period, transmission of a specific wireless frame (e.g., a response frame (ACK) that responds to reception of an uplink frame) may be permitted. For example, if the ACK transmission time is not included in the limit on the total transmission time, transmission of the ACK may be permitted.

[0128] On the other hand, the situation for STA-Y is as follows:

[0129] The control device 100 controls STA-Y to use NIC-1 to communicate with the AP. In other words, the control device 100 sets NIC-1 as the selected NIC for STA-Y. In the first period from time t1s to time t1e, the AP also uses NIC-1 as the selected NIC, so the AP and STA-Y can communicate with each other on the first channel CH-1.

[0130] However, the channel used for communication during the second period from time t2s to time t2e is the second channel CH-2. STA-Y is not equipped with NIC-2 for the second channel CH-2, and therefore cannot communicate on the second channel CH-2. However, if communication by STA-Y is completely stopped during the second period, communication efficiency will decrease.

[0131] Therefore, according to this embodiment, the control device 100 controls the STA-Y to execute the "limited communication process" in the second period. Specifically, the control device 100 controls the STA-Y to continue data transmission using the NIC-1 even in the second period. However, the second period corresponds to a transmission prohibition period for the NIC-1 on the AP side. Therefore, the control device 100 controls the STA-Y not to request any downstream frames from the AP in the second period. For example, the STA-Y transmits upstream frames to the AP with a "NO ACK" policy.

[0132] Alternatively, when transmission of an ACK is permitted even during a transmission inhibition period, the control device 100 may control the STA-Y so that it requests an ACK but does not request any downlink frames other than the ACK from the AP.

[0133] In general, in a period in which none of NIC-1 to NIC-M of STA-Y supports the same channel as the selected NIC in the AP, the control device 100 controls STA-Y to execute limited communication processing. In the limited communication processing, STA-Y does not request any downlink frames or downlink frames other than ACK from the AP.

[0134] Fig. 20 is a flow chart for explaining the limited communication process. It is assumed that the control device 100 transmits an NIC switching instruction to each STA including STA-Y (see Section 3, Figs. 5, 7, 9, and 13). STA-Y receives the NIC switching instruction from the control device 100 (step S70). If the instruction is to switch to a NIC that STA-Y does not support, STA-Y does not switch the NIC to be used. Instead, STA-Y sets not to request any downlink frames or downlink frames other than ACK from the AP (step S71). Then, STA-Y returns a response to the control device 100 (step S72).

[0135] As described above, according to this embodiment, it is possible to realize a mixed environment in which STA-X and STA-Y coexist. Also, even if the NIC on the AP side is in a transmission prohibition period, it is possible to continue the communication of STA-Y by making the STA-Y execute the limited communication process, thereby improving the communication efficiency. [Explanation of symbols]

[0136] 1...wireless communication system, 10...wireless communication device, 11...processor, 12...storage device, 13...control program, 14...management information, 15...interface, 16...timer, 100...control device, 110...processor, 120...storage device, 130...control program, 140...management information, 150...interface, 160...timer, AP...base station, NIC...network interface controller, STA...wireless terminal, STA-X...first wireless terminal, STA-Y...second wireless terminal

Claims

1. A plurality of wireless communication devices constituting a wireless communication network; one or more control devices for controlling the plurality of wireless communication devices; Equipped with each of the plurality of wireless communication devices includes a plurality of network interface controllers that perform wireless communication on different non-overlapping channels; The total transmission time per unit time is limited for each channel, the channel switching process is a process of switching the usage states of the plurality of network interface controllers in each of the plurality of wireless communication devices; The one or more control devices include one or more storage devices that store management information including a timing of the channel switching process, and execute the channel switching process at the timing indicated by the management information; The one or more control devices control the wireless communication devices so that they use the same channel network interface controller for the same period. Wireless communication system.

2. 2. The wireless communication system according to claim 1, the plurality of network interface controllers include a first network interface controller that performs wireless communication on a first channel, and a second network interface controller that performs wireless communication on a second channel different from the first channel; The one or more control devices alternately perform a first mode using the first network interface controller and a second mode using the second network interface controller in each of the plurality of wireless communication devices. Wireless communication system.

3. 3. The wireless communication system according to claim 1, The one or more control devices control each of the plurality of wireless communication devices to stop packet forwarding to a network interface controller other than the network interface controller to be used. Wireless communication system.

4. 3. The wireless communication system according to claim 1, The one or more control devices control each of the plurality of wireless communication devices to stop operation of network interface controllers other than the network interface controller to be used. Wireless communication system.

5. 3. The wireless communication system according to claim 1, The one or more control devices control each of the plurality of wireless communication devices to set a transmission prohibition period for a network interface controller other than the network interface controller to be used based on a sleep function or an access restriction function. Wireless communication system.

6. A wireless communication control method for controlling a plurality of wireless communication devices constituting a wireless communication network, comprising: each of the plurality of wireless communication devices includes a plurality of network interface controllers that perform wireless communication on different non-overlapping channels; The total transmission time per unit time is limited for each channel, the channel switching process is a process of switching the usage states of the plurality of network interface controllers in each of the plurality of wireless communication devices; The wireless communication control method includes: acquiring management information including a timing of the channel switching process from one or more storage devices, and executing the channel switching process at the timing indicated by the management information; A process of controlling the plurality of wireless communication devices to use the same channel network interface controller for the same period of time; Includes A wireless communication control method.

7. A control device for controlling a plurality of wireless communication devices constituting a wireless communication network, each of the plurality of wireless communication devices includes a plurality of network interface controllers that perform wireless communication on different non-overlapping channels; The total transmission time per unit time is limited for each channel, the channel switching process is a process of switching the usage states of the plurality of network interface controllers in each of the plurality of wireless communication devices; the control device includes a processor and a storage device that stores management information including a timing of the channel switching process; the processor executes the channel switching process at the timing indicated by the management information stored in the storage device; The processor controls the plurality of wireless communication devices to use the same channel network interface controller for the same period. Control device.

8. A control program that, when executed by a computer, causes the computer to realize the control device according to claim 7.

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