Wireless communication system, wireless communication method, and wireless communication terminal

Abstract

The wireless communication system according to an embodiment is characterized in that: a control device includes a collection unit that collects observation result information indicating a result of observation of a use situation of a channel, the observation being carried out by a device not using the channel in the vicinity of a wireless communication terminal; a determination unit that determines, on the basis of the observation result information collected by the collection unit, whether the wireless communication terminal can use the channel; and a result transmission unit that transmits determination result information indicating the result determined by the determination unit in response to a request from the wireless communication terminal and the wireless communication terminal includes a control unit that controls the wireless communication terminal to use the channel when the received determination result information indicates that the channel can be used.

Description

[Technical Field]

[0001] The present invention relates to a wireless communication system, a wireless communication method, and a wireless communication terminal. [Background technology]

[0002] With the development of IoT (Internet of Things) wireless communications, there is a need to transmit not only sensor data but also image data and large volumes of data over wide wireless areas. For example, the 920 MHz band is being broadened and transmission capacity is being expanded through revisions to domestic laws and regulations.

[0003] However, the 920 MHz band has a total transmission time rate (a limit on the total transmission time per hour) of 10%, which means that the amount of data that a single terminal can transmit can be significantly less than the actual performance of the radio.

[0004] However, the limit on the total transmission time rate is a regulation for the shared band between active tags (wireless communication terminals such as sensor communication systems that transmit and receive by sensing the carrier before transmitting). There is no limit on the total transmission time rate for the priority band of passive tags (wireless communication terminals of electronic tag systems such as RFID that do not transmit radio waves themselves but return a response to transmitted radio waves). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] 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, IEEE Computer Society, Developed by the LAN / MAN Standards Committee, IEEE Std 802.11-2020 (Revision of IEEE Std 802.11-2016), Approved 3 December 2020, IEEE SA Standards Board [Non-patent document 2] "920MHz-BAND TELEMETER, TELECONTROL AND DATA TRANSMISSION RADIO EQUIPMENT", ARIB STANDARD, ARIB STD-T108 Version 1.4, Established February 14, 2012, Revised April 23, 2021, Association of Radio Industries and Businesses Summary of the Invention [Problem to be solved by the invention]

[0006] Although there is no limit on the total transmission time rate for the passive tag priority band, the carrier sense time before transmission is specified to be 5 msec or more, which is significantly longer than the carrier sense time (128 μsec or more) for the active tag shared band.

[0007] Furthermore, the passive tag priority band requires a 50 msec pause after the radio wave is emitted (the time to stop transmission of anything other than response signals such as ACK) (see Non-Patent Document 2). However, once a carrier sense of 5 msec or more is performed in the passive tag priority band, there is no pause and the carrier sense time is 128 μsec, as long as it is within 4 seconds of the initial radio wave emission.

[0008] Furthermore, in the passive tag priority band, when single frames such as beacon frames are periodically generated and transmission is attempted, the waiting time of surrounding terminals becomes long even if transmission is attempted all at once.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a wireless communication system, a wireless communication method, and a wireless communication terminal that can check whether a frequency band is available for use in a short period of time. [Means for solving the problem]

[0010] A wireless communication system according to one embodiment of the present invention comprises a wireless communication terminal that is enabled to perform wireless communication using a first channel that has a limit on the total transmission time rate and a second channel that has a longer pause time for suspending transmissions other than response signals and a longer carrier sense time before transmission than the first channel and has no limit on the total transmission time rate; and a control device that controls the wireless communication terminal. The control device has a collection unit that collects observation result information indicating the results of observation of the usage status of the second channel by devices that are not using the second channel around the wireless communication terminal, a judgment unit that judges whether the wireless communication terminal can use the second channel based on the observation result information collected by the collection unit, and a result transmission unit that transmits judgment result information indicating the result of the judgment made by the judgment unit in response to a request from the wireless communication terminal. The wireless communication terminal has a request transmission unit that requests the control device to transmit judgment result information by the result transmission unit, a result receiving unit that receives the judgment result information sent by the result transmission unit, and a control unit that controls the wireless communication terminal to use the second channel when the judgment result information received by the result receiving unit indicates that the second channel is available.

[0011] In addition, a wireless communication method according to one embodiment of the present invention is a wireless communication method performed by a wireless communication system including a wireless communication terminal that is enabled to perform wireless communication using a first channel that has a limit on the total transmission time rate and a second channel that has a pause time for halting transmission other than response signals and a carrier sense time before transmission that is longer than those of the first channel and has no limit on the total transmission time rate, and a control device that controls the wireless communication terminal, and is characterized by including a collection step of collecting observation result information that indicates the results of observation of the usage status of the second channel by devices that are not using the second channel around the wireless communication terminal, a determination step of determining whether the wireless communication terminal can use the second channel based on the collected observation result information, and a control step of controlling the wireless communication terminal to use the second channel when determination result information that indicates the result of the determination indicates that the second channel is usable.

[0012] In addition, a wireless communication terminal according to one embodiment of the present invention is a wireless communication terminal that uses a first channel that has a limit on the total transmission time rate and a second channel that has a longer pause time for stopping transmissions other than response signals and a longer carrier sense time before transmission than the first channel and has no limit on the total transmission time rate, and performs wireless communication in accordance with the control of a control device, and is characterized by having an observation unit that observes the usage status of the second channel when the second channel is not being used to transmit data frames, a request transmission unit that requests the control device to transmit determination result information indicating the result of a determination on whether or not the second channel can be used based on the usage status of the second channel observed by the observation unit, a result receiving unit that receives the determination result information sent by the control device in accordance with a request from the request transmission unit, and a control unit that controls the wireless communication terminal to use the second channel when the determination result information received by the result receiving unit indicates that the second channel is usable. [Effects of the Invention]

[0013] According to the present invention, it is possible to check in a short time whether a frequency band is available for use. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram illustrating an example of the configuration of a wireless communication system according to an embodiment. [Figure 2] FIG. 1 is a diagram illustrating an example of the configuration of a base station. [Figure 3] FIG. 10 is a diagram showing combinations of parameters for transmission time restrictions in each frequency band of the 920 MHz band. [Figure 4] FIG. 1 is a diagram showing channels and center frequencies of a passive tag priority band in the 920 MHz band. [Figure 5] FIG. 2 is a functional block diagram illustrating functions of a control device. [Figure 6] FIG. 2 is a functional block diagram illustrating functions of a base station (wireless communication terminal). [Figure 7]10 is a diagram illustrating timings at which a wireless communication device according to an embodiment transmits a transmission frame in a passive tag priority band. [Figure 8] 1 is a flowchart illustrating an example of an operation of a wireless communication system according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] A wireless communication system according to an embodiment will be described below with reference to the drawings. Fig. 1 is a diagram showing an example of the configuration of a wireless communication system according to an embodiment. As shown in Fig. 1, the wireless communication system according to an embodiment includes, for example, a base station 1, a transmitting terminal 2, a control device 3, and multiple wireless terminals 4, which are wireless communication terminals.

[0016] The base station 1 receives a transmission frame transmitted by the transmitting terminal 2 under the control of the control device 3. The wireless terminal 4 has a function of observing (scanning) the radio wave conditions (frequency conditions) around the control device 3, and transmits the observation results to the control device 3.

[0017] The wireless terminal 4 performs a scan by continuously or piecemeal executing carrier sense for, for example, 5 msec or more. The wireless terminal 4 may also record the number of times the channel is determined to be busy, or may use a simple spectrum analyzer to detect and record the presence or absence of a signal in that time period. For example, if the wireless terminal 4 performs a scan 100 times every minute and the scan result never indicates a busy state, it may determine that the passive tag priority band is not in use in that location or time period.

[0018] Then, the wireless communication terminals (base station 1 and transmitting terminal 2) that wish to use the passive tag priority band make an inquiry to the control device 3. The control device 3 determines whether or not to use the passive tag priority band based on the collected information, and responds with the result to the wireless communication terminal that made the inquiry.

[0019] The control device 3 may also record the collected data together with the location information and store it as a database. In this case, the control device 3 can notify the base station 1 of the usage status of the passive tag priority band without the wireless terminal 4 having to perform a scan each time.

[0020] The transmitting terminal 2 may also have the functions of the control device 3. Furthermore, the base station 1 and the transmitting terminal 2 may each be a wireless communication terminal having the same functions.

[0021] Fig. 2 is a diagram showing an example of the configuration of the base station 1. As shown in Fig. 2, the base station 1 includes, for example, a memory 10, a drive 11, a timer 12, a user interface 13, a wired communication module 14, a first wireless communication module 15-1, a second wireless communication module 15-2, and a control circuit 16, which are connected via a bus 17.

[0022] The memory 10 is a storage device that stores, for example, a control program 100 and management information 102. The drive 11 reads and writes data from and to a storage medium 110. The timer 12 measures the time when the base station 1 performs control. The user interface 13 is an input / output device that includes, for example, a keyboard and a display.

[0023] The wired communication module 14 is a module that performs wired communication with other devices. The first wireless communication module 15-1 and the second wireless communication module 15-2 each have a different NIC, and each perform wireless communication with other devices using a different channel.

[0024] The first wireless communication module 15-1 performs wireless communication using, for example, a passive tag priority band (see FIG. 2). The second wireless communication module 15-2 performs wireless communication using, for example, an active tag shared band (see FIG. 2). The number of wireless communication modules included in the base station 1 is not limited to two.

[0025] The control circuit 16 includes a CPU 160 and controls each unit constituting the base station 1. For example, the control circuit 16 performs control using the time measured by the timer 12.

[0026] Figure 3 shows the combination of parameters for transmission time limits in each frequency band of the 920 MHz band. Figure 4 shows the channels and center frequencies of the passive tag priority band in the 920 MHz band. (A) in Figure 3 shows the parameters of the passive tag priority band. (B) in Figure 3 shows the parameters of the active tag shared band.

[0027] The passive tag priority band is a channel with no limit on the total transmission time rate. In the passive tag priority band, the carrier sense time is specified to be long so that the passive tag operation is not hindered by the transmission of the active tag, and a pause time is provided.

[0028] Specifically, the passive tag priority band is stipulated to have a carrier sense time of 5 msec or more before transmission, and a pause time of 50 msec or more after the radio wave is emitted during which transmissions other than response signals are stopped. Note that once a carrier sense of 5 msec or more is performed, the passive tag priority band does not require a pause time as long as it is within 4 seconds of the initial radio wave emission, and the carrier sense time is also stipulated to be 128 μsec.

[0029] In other words, the passive tag priority band is free from these restrictions for 4 seconds after the radio wave is emitted after a carrier sense of 5 msec or more, allowing for efficient transmission.

[0030] The active tag shared band is a channel with a limit on the total transmission time rate. Specifically, the active tag shared band has a limit of 10% or less, and the carrier sense time before transmission is set to 128 μsec. In other words, the active tag priority band has a limit of 360 seconds per hour for the total transmission time, which can make large-volume communication difficult.

[0031] 5 is a functional block diagram illustrating the functions of the control device 3. As shown in FIG. 5, the control device 3 includes a receiving unit 30, a collecting unit 31, a storage unit 32, a determining unit 33, a result transmitting unit 34, and a control unit 35.

[0032] The receiving unit 30 receives information transmitted by the base station 1 and the wireless terminal 4, and outputs the received information to the collecting unit 31.

[0033] The collection unit 31 collects the information received by the receiving unit 30 and outputs it to the storage unit 32. For example, the collection unit 31 collects observation result information indicating the results of observation of the usage status of the channels of the passive tag priority band by wireless terminals 4 that are not using channels of the passive tag priority band around the base station (wireless communication terminal) 1, and outputs it to the storage unit 32.

[0034] Furthermore, the collection unit 31 collects, along with observation result information indicating the results of observing the usage status of the channels of the passive tag priority band, location information (and time information) indicating the location (and time) at which a wireless terminal 4 that is not using a channel of the passive tag priority band observed the usage status of the channel of the passive tag priority band, and outputs this to the memory unit 32.

[0035] The storage unit 32 stores information such as the observation result information collected by the collection unit 31 and the results of the determination by the determination unit 33. For example, the storage unit 32 stores the observation result information collected by the collection unit 31 together with the position information.

[0036] The determination unit 33 determines whether the base station 1 and the transmitting terminal 2 can use a channel in the passive tag priority band based on the observation result information collected by the collection unit 31, and outputs the determination result to the storage unit 32. Furthermore, when the collection unit 31 has not collected new observation result information, the determination unit 33 determines whether the base station 1 and the transmitting terminal 2 can use a channel in the passive tag priority band based on the observation result information stored in the storage unit 32.

[0037] Furthermore, the determining unit 33 may determine, based on the observation result information and location information stored in the storage unit 32, whether or not the base station 1 and the transmitting terminal 2 can use a channel in the passive tag priority band.

[0038] The result transmission unit 34 transmits determination result information indicating the result of the determination made by the determination unit 33 in response to a request from the base station 1.

[0039] The control unit 35 controls each unit constituting the control device 3 .

[0040] 6 is a functional block diagram illustrating functions of the base station (wireless communication terminal) 1. As shown in FIG. 6, the base station 1 includes, for example, a request transmitting unit 60, a result receiving unit 61, a storage unit 62, and a control unit 63.

[0041] The transmitting terminal 2 may also have the functions of the base station 1 shown in FIG. 6, and may further have an observation unit 64 so as to function in the same way as the wireless terminal 4.

[0042] The request sending unit 60 requests the control device 3 to send the determination result information from the result sending unit 34 of the control device 3.

[0043] The result receiving unit 61 receives the determination result information transmitted by the result transmitting unit 34 of the control device 3 and outputs it to the storage unit 62.

[0044] The storage unit 62 stores the information received by the result receiving unit 61 and the like.

[0045] The control unit 63 controls each unit constituting the base station 1 (as well as the transmitting terminal 2). For example, when the determination result information received by the result receiving unit 61 indicates that a channel in the passive tag priority band is available, the control unit 63 controls the base station 1 (as well as the transmitting terminal 2) to use a channel in the passive tag priority band.

[0046] When a channel in the passive tag priority band is not being used for transmitting a data frame, the observation unit 64 observes the usage status of surrounding channels in the passive tag priority band, and outputs the observation result to the control unit 63 or the like.

[0047] In this case, the base station 1 (and the transmitting terminal 2 as well) requests the control device 3 to transmit determination result information indicating the result of the determination made by the request sending unit 60 on whether or not it is possible to use a channel in the passive tag priority band based on the usage status observed by the observation unit 64.

[0048] 7 is a diagram showing the timing at which a base station 1 according to an embodiment transmits a transmission frame in a passive tag priority band. IEEE 802.11ah is one of the wireless communication standards used in the sub-1 GHz band. In IEEE 802.11ah, the time length of a wireless communication frame is 28 msec.

[0049] Therefore, even if the transmission time limit is 4 seconds or less, if there are multiple wireless communication devices and traffic, the delay time for the traffic of each wireless communication device may be long if there are many of them.In addition, between data frame communications such as TCP ACK, necessary uplink and downlink communications are also transmitted alternately.

[0050] 8 is a flowchart showing an example of the operation of the wireless communication system according to an embodiment. For example, the base station 1 performs carrier sense for 5 msec or more 100 times and counts the number of times it becomes busy (S100).

[0051] The control device 3 determines whether or not a busy state with a specified busy rate (for example, 20 or more times out of 100 times) has been observed (S102). If the control device 3 determines that a busy state with the specified busy rate has been observed (S102: Yes), it proceeds to the process of S106, and if the control device 3 determines that a busy state with the specified busy rate has not been observed (S102: No), it proceeds to the process of S104.

[0052] In step 104 (S104), the control device 3 determines that the base station 1 and the transmitting terminal 2 can use the passive tag priority band.

[0053] In step 106 (S106), the control device 3 determines that the base station 1 and the transmitting terminal 2 cannot use the passive tag priority band.

[0054] In this way, the wireless communication system of one embodiment determines whether the base station 1 and the transmitting terminal 2 can use a channel in the passive tag priority band based on the observation result information collected by the collection unit 31, so that it is possible to confirm whether the frequency band can be used in a short period of time.

[0055] Furthermore, the wireless communication system may perform a threshold determination based on the observation result information collected by the collection unit 31, and determine that the passive tag priority band is available at the threshold.

[0056] For example, the passive tag priority band may be determined to be unavailable if the signal occupancy rate observed by a simple spectrum analyzer is equal to or greater than a predetermined value (e.g., 20%).Also, if the carrier sense busy rate exceeds a predetermined value (e.g., 20%), the passive tag priority band may be determined to be unavailable.

[0057] Furthermore, the control device 3 may determine whether or not a frequency channel is available based on the location information of the wireless terminal 4, using the determination result of the range in which it is determined that there is an influence (for example, within several hundred meters).

[0058] In addition, each function possessed by the base station 1, the transmitting terminal 2, the control device 3, and the wireless terminal 4 may be partially or entirely configured by hardware such as a PLD (Programmable Logic Device) or an FPGA (Field Programmable Gate Array), or may be configured as a program executed by a processor such as a CPU.

[0059] For example, the base station 1, the transmitting terminal 2, the control device 3, and the wireless terminal 4 can each be realized using a computer and a program, and the program can be recorded on a storage medium or provided via a network. [Explanation of symbols]

[0060] 1 base station, 2 transmitting terminal, 3 control device, 4 wireless terminal, 10 memory, 12 timer, 13 user interface, 14 wired communication module, 15-1 first wireless communication module, 15-2 second wireless communication module, 16 control circuit, 17 bus, 30 receiving unit, 31 collecting unit, 32 storage unit, 33 determining unit, 34 result transmitting unit, 35 control unit, 60 request transmitting unit, 61 result receiving unit, 62 storage unit, 63 control unit, 64 observation unit, 100 control program, 102 management information, 110 storage medium, 160 CPU

Claims

1. a wireless communication terminal that is enabled to perform wireless communication using a first channel that has a limit on the total transmission time rate and a second channel that has a pause time for stopping transmissions other than response signals and a carrier sense time before transmission that are longer than those of the first channel and has no limit on the total transmission time rate; a control device that controls the wireless communication terminal; Equipped with The control device a collection unit that collects observation result information indicating results of observation of a usage state of the second channel by devices not using the second channel around the wireless communication terminal; a determination unit that determines whether or not the wireless communication terminal is allowed to use the second channel based on the observation result information collected by the collection unit; a result transmission unit that transmits determination result information indicating the result of the determination made by the determination unit in response to a request from the wireless communication terminal; and The wireless communication terminal a request transmission unit that requests the control device to transmit determination result information by the result transmission unit; a result receiving unit that receives the determination result information transmitted by the result transmitting unit; a control unit that controls the wireless communication terminal to use the second channel when the determination result information received by the result receiving unit indicates that the second channel is available; A wireless communication system comprising:

2. The control device further comprising a storage unit that stores the observation result information collected by the collection unit; The determination unit When the collecting unit has not collected new observation result information, it is determined whether or not the wireless communication terminal is allowed to use the second channel based on the observation result information stored in the storage unit.

2. The wireless communication system according to claim 1, wherein:

3. The collecting unit collecting location information indicating a location where a device not using the second channel observed the usage status of the second channel together with observation result information indicating a result of observing the usage status of the second channel; The storage unit The observation result information and the position information collected by the collection unit are stored together, The determination unit determining whether the wireless communication terminal is allowed to use the second channel based on the observation result information and location information stored in the storage unit; 3. The wireless communication system according to claim 2, wherein:

4. A wireless communication method performed by a wireless communication system including a wireless communication terminal that is enabled to perform wireless communication using a first channel that has a limit on the total transmission time rate and a second channel that has a pause time for stopping transmissions other than response signals and a carrier sense time before transmission that is longer than those of the first channel and has no limit on the total transmission time rate, and a control device that controls the wireless communication terminal, a collection step of collecting observation result information indicating results of observation of a usage state of the second channel by devices not using the second channel around the wireless communication terminal; a determination step of determining whether the wireless communication terminal is allowed to use the second channel based on the collected observation result information; a control step of controlling the wireless communication terminal to use the second channel when determination result information indicating a result of the determination indicates that the second channel is available; A wireless communication method comprising:

5. The control device a storage unit for storing collected observation result information; In the determination step, When new observation result information has not been collected, determining whether or not the wireless communication terminal is allowed to use the second channel based on the observation result information stored in the storage unit.

5. The wireless communication method according to claim 4, wherein:

6. In the collecting step, collecting location information indicating a location where a device not using the second channel observed the usage status of the second channel together with observation result information indicating a result of observing the usage status of the second channel; The storage unit Collected observation result information and location information are stored together, In the determination step, determining whether the wireless communication terminal is allowed to use the second channel based on the observation result information and location information stored in the storage unit; 6. The wireless communication method according to claim 5,

7. A wireless communication terminal that performs wireless communication under the control of a control device using a first channel that has a limit on the total transmission time rate and a second channel that has a pause time for stopping transmissions other than response signals and a carrier sense time before transmission that are longer than those of the first channel and has no limit on the total transmission time rate, an observation unit that observes a usage state of the second channel when the second channel is not being used for transmitting data frames; a request transmission unit that requests the control device to transmit determination result information indicating a result of determining whether or not the second channel is available based on the usage status of the second channel observed by the observation unit; and a result receiving unit that receives the determination result information transmitted by the control device in response to a request from the request transmitting unit; a control unit that controls the wireless communication terminal to use the second channel when the determination result information received by the result receiving unit indicates that the second channel is available; A wireless communication terminal comprising:

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