WO2016203623A1

WO2016203623A1 - Communication device, communication method, and communication system

Info

Publication number: WO2016203623A1
Application number: PCT/JP2015/067649
Authority: WO
Inventors: 笠間　晃一朗
Original assignee: 富士通株式会社
Priority date: 2015-06-18
Filing date: 2015-06-18
Publication date: 2016-12-22

Abstract

This communication device (20) has a transmission unit (22), a determination unit (23) and a change unit (24). The transmission unit (22) transmits a transmission request to a base unit within a data transmission-enabled period. The determination unit (23) determines whether or not acknowledgement of the transmission request is received within a prescribed interval of time following transmission of the transmission request by the transmission unit (22). On the basis of the determination results from the determination unit (23), the change unit (24) changes a duty ratio, which is the proportion the transmission-enabled period constitutes in the prescribed interval of time. When the change unit (24) changes the duty ratio, the transmission unit (22) transmits the transmission request to the base unit within a transmission-enabled period that corresponds to the changed duty ratio.

Description

COMMUNICATION DEVICE, COMMUNICATION METHOD, AND COMMUNICATION SYSTEM

The present invention relates to a communication device, a communication method, and a communication system.

There is a system in which a plurality of communication devices that operate as slave units communicate with one communication device that operates as a base unit using the same frequency. As such a system, for example, a communication system using Bluetooth (registered trademark) is known. In Bluetooth, each child device suppresses collision of data transmitted from each child device by hopping a channel used for communication in a pattern decided with the parent device.

In addition, a wireless tag search system that performs communication between an active wireless tag and a tag search device by BLE (Bluetooth Low Energy) is known (for example, see Patent Document 1 below).

JP 2014-216726 A

By the way, in a system in which a plurality of slave units and one master unit communicate with each other using the same frequency, when a usable frequency is reduced or the number of slave units is increased, transmission is performed from each slave unit. The probability that the data collide will increase. As a result, communication between each child device and the parent device may be difficult. In particular, in BLE, data collision is suppressed by hopping channels in a pattern determined by each slave unit with the master unit. However, since the usable frequency is limited, the same channel can be used simultaneously. Increases the probability of being used. Therefore, when the number of slave units increases, communication between each slave unit and the master unit may become difficult.

The technology disclosed in the present application suppresses collision of data transmitted from each communication device that operates as a slave in BLE communication.

In one aspect, a communication device used in a communication system in which a plurality of communication devices operating as slave units communicate with a single master unit using the same frequency includes a transmission unit, a determination unit, a change unit, Have The transmission unit transmits a transmission request to the parent device within a data transmittable period. The determination unit determines whether an acknowledgment for the transmission request is received within a predetermined time after the transmission unit transmits the transmission request. The changing unit changes a duty ratio that is a ratio of a transmittable period to a predetermined period based on a determination result by the determining unit. When the duty ratio is changed by the changing unit, the transmitting unit transmits a transmission request to the parent device within a transmittable period corresponding to the changed duty ratio.

According to one embodiment, it is possible to suppress collision of data transmitted from each communication device operating as a slave unit.

FIG. 1 is a diagram illustrating an example of a communication system. FIG. 2 is a block diagram illustrating an example of a communication device. FIG. 3 is a diagram illustrating an example of a pattern table. FIG. 4 is a diagram illustrating the duty ratio and the first offset. FIG. 5 is a diagram illustrating an example of the division table. FIG. 6 is a diagram illustrating an example of the second offset. FIG. 7 is a diagram illustrating an example of the change table. FIG. 8 is a diagram illustrating an example of the information table. FIG. 9 is a flowchart illustrating an example of a change table creation process. FIG. 10 is a flowchart illustrating an example of the communication management process. FIG. 11 is a flowchart illustrating an example of control processing for the driving period of the wireless unit. FIG. 12 is a diagram illustrating an example of hardware of the communication device.

Hereinafter, embodiments of a communication device, a communication method, and a communication system disclosed in the present application will be described in detail based on the drawings. The following examples do not limit the disclosed technology. Each embodiment can be appropriately combined within a range in which processing contents are not contradictory.

[Communication system 10]
FIG. 1 is a diagram illustrating an example of a communication system 10. The communication system 10 includes a communication device 12 and a plurality of communication devices 20-1 to 20-n. The communication system 10 is used in a predetermined area such as a company office, factory, or event venue. Hereinafter, the plurality of communication devices 20-1 to 20-n are collectively referred to as the communication device 20 without being distinguished from each other.

The communication device 12 operates as a parent device of the BLE communication system, and each of the plurality of communication devices 20-1 to 20-n operates as a child device of the BLE communication system. The plurality of communication devices 20 perform wireless communication with one communication device 12 using the same frequency. In the present embodiment, the communication device 12 and each communication device 20 perform wireless communication with each other by BLE.

The communication device 12 transmits / receives data to / from each communication device 20. Further, the communication device 12 transfers data transmitted / received between the communication devices 20. In addition, the communication device 12 transfers the data transmitted from each communication device 20 to another device via the communication line 11 or receives data received from another device via the communication line 11 as a destination. Transfer to the communication device 20. Note that the communication device 12 may operate as a slave unit with other communication devices 12.

[Communication device 20]
Next, each communication device 20 that operates as a slave will be described. FIG. 2 is a block diagram illustrating an example of the communication device 20. For example, as illustrated in FIG. 2, the communication device 20 includes a wireless unit 21, a transmission unit 22, a determination unit 23, a change unit 24, a holding unit 25, a creation unit 26, a reception unit 27, and an antenna 28. The holding unit 25 holds a pattern table 250, a division table 251, a change table 252, and an information table 253.

FIG. 3 is a diagram illustrating an example of the pattern table 250. In the pattern table 250, for example, as shown in FIG. 3, a pattern number 2500 is stored in association with a plurality of combinations of the duty ratio 2502 and the first offset 2503. The pattern number 2500 is an example of information indicating a method for changing the combination of the duty ratio and the first offset. Each combination of the duty ratio 2502 and the first offset 2503 is associated with a combination number 2501 that identifies each combination.

Here, the duty ratio and the first offset will be described. FIG. 4 is a diagram illustrating the duty ratio and the first offset. In FIG. 4, T ₀ indicates a predetermined repetition period, and t ₀ indicates the start timing of the repetition period T ₀ . In this embodiment, the repetition period T ₀ is, for example, 20 seconds. In FIG. 4, “drive” indicates a period during which the wireless unit 21 is driven, and “stop” indicates a period during which the wireless unit 21 is stopped. Further, the period during which the wireless unit 21 is driven is an example of a transmittable period.

In the present embodiment, the duty ratio is expressed as a ratio of a period during which the wireless unit 21 is driven with respect to the repetition period T ₀ . In the example shown in FIG. 4A, since the radio unit 21 is driven over the entire period of the repetition cycle T ₀ , the duty ratio is 100%. In the example shown in FIG. 4B, the duty ratio is (T ₁ / T ₀ ) × 100% because the radio unit 21 is driven in the period T ₁ in the repetition period T ₀ . For example, as shown in FIG. 4C, an offset ΔT ₁ from the start timing of the repetition period T _{0 to} the start timing of the period T ₁ driven by the radio unit 21 is defined as a first offset.

In FIG. 3, each pattern number 2500 is associated with a plurality of different combinations of duty ratios 2502 and first offsets 2503. Different pattern numbers 2500 may be associated with the same combination of duty ratio 2502 and first offset 2503. However, between different pattern numbers 2500, it is preferable that the duty ratio 2502 and the first offset 2503 of the same combination are associated with different combination numbers 2501.

FIG. 5 is a diagram illustrating an example of the division table 251. The division table 251 stores a total number range 2510, a division number 2511, a group number 2512, and a second offset 2513 in association with each other. A total range 2510 indicates a total range of communication devices 20 used in a predetermined area such as an event venue. In the total range 2510 illustrated in FIG. 5, “101 to 200” indicates a range of 101 to 200. The division number 2511 indicates the number of groups when a plurality of communication devices 20 are divided into groups. The group number 2512 is information for identifying each group when the plurality of communication devices 20 are divided into groups. The second offset 2513 will be described with reference to FIG.

FIG. 6 is a diagram illustrating an example of the second offset. The second offset is defined as an offset from the start timing t ₀ of the reference repetition period T _{0 to} the start timing of the repetition period of the target group. In group 1 shown in FIG. 6 (a) for example, at the start timing t ₀ of the repetition period T _0, the repetition period T ₀₁ is started. Therefore, in group 1 shown in FIG. 6A, the second offset is zero. For example, in the group 2 shown in FIG. 6B, the repetition period T ₀₂ starts after ΔT ₂ has elapsed from the start timing t ₀ of the repetition period T ₀ . Therefore, the group 2 shown in FIG. 6 (b), the second offset is [Delta] T _2. As is apparent from FIG. 6, when the second offset ΔT ₂ has a length that is an integral multiple of the repetition period T ₀ , the second offset is the same as zero. In this embodiment, the length of the repetition period of each group is the same.

FIG. 7 is a diagram illustrating an example of the change table 252. For example, as shown in FIG. 7, the change table 252 stores a total number 2520, a division number 2521, a group number 2522, an order range 2523, a pattern number 2524, and a second offset 2525 in association with each other.

The total number 2520 indicates the total number of communication devices 20 used in a predetermined area such as an event venue. The division number 2521 indicates the number of groups when the plurality of communication devices 20 are divided into groups. The group number 2522 is information for identifying each group when the plurality of communication devices 20 are divided into groups.

The order range 2523 is an order range of the communication devices 20 belonging to each group. Each communication apparatus 20 is assigned an order according to a predetermined rule. In the present embodiment, each communication device 20 is assigned a number indicating the order in ascending order of the identification information value of the communication device 20. The identification information of the communication device 20 is, for example, a BD (Bluetooth Device) address or a MAC (Media Access Control) address.

The pattern number 2524 is any pattern number registered in the pattern table 250. The second offset 2525 is an offset from the start timing of the reference repetition cycle to the start timing of the repetition cycle of the target group.

FIG. 8 is a diagram illustrating an example of the information table 253. In the information table 253, for example, as shown in FIG. 8, an item 2530 and a value 2531 corresponding to the item 2530 are stored. The items 2530 include, for example, the BD address of the own device, the order assigned to the own device, the total number of communication devices 20 (including the own device) used in the same area, and the connection state between the own device and the communication device 12 The communication speed between the device itself and the communication device 12 is stored. In this embodiment, the BD address, the order, and the total number are written in the information table 253 when the communication device 20 is shipped. In the present embodiment, the connection state and the communication speed value are rewritten as needed according to the state of communication with the communication device 12.

Referring back to FIG. The radio unit 21 performs processing such as encoding and modulation on the data received from the transmission unit 22, converts the processed signal into a predetermined frequency, and transmits the signal from the antenna 28. The radio unit 21 converts a signal received via the antenna 28 into a baseband signal. Radio section 21 then performs processing such as demodulation and decoding on the converted signal, and outputs the received data after processing to determination section 23 and a reception processing section (not shown). The wireless unit 21 is driven in response to an instruction from the transmission unit 22 and stopped in response to an instruction from the transmission unit 22.

The transmission unit 22 receives the duty ratio, the first offset, and the second offset from the changing unit 24. Then, the transmission unit 22 controls driving and stopping of the radio unit 21 according to the duty ratio, the first offset, and the second offset received from the changing unit 24.

Further, when a transmission request is generated, the transmission unit 22 outputs the transmission request to the wireless unit 21 during the period in which the wireless unit 21 is driven. As a result, the transmission request is transmitted to the communication device 12 via the antenna 28. In addition, the transmission unit 22 outputs information indicating that the transmission request has been transmitted to the determination unit 23 and the change unit 24. When an acknowledgment to the transmission request is transmitted from the communication device 12, the transmission unit 22 outputs data to be transmitted to the wireless unit 21 during the period when the wireless unit 21 is driven. As a result, data is transmitted to the communication device 12 via the antenna 28. Further, the transmission unit 22 outputs to the determination unit 23 that data has been transmitted. Further, when the data transmission is completed, the communication end is output to the determination unit 23 and the change unit 24.

If a positive response is not received from the communication device 12 within a predetermined time after transmitting the transmission request or data to the communication device 12, the transmission unit 22 retries transmission of the transmission request or data. If no acknowledgment is received from the communication device 12 even after a predetermined number of retries, the transmission unit 22 stops transmission of the transmission request or data.

The determination unit 23 refers to the reception data output from the wireless unit 21 when the transmission unit 22 outputs that the transmission request has been transmitted, and within a predetermined time after the transmission request is transmitted. It is determined whether or not an affirmative response is received. When an acknowledgment to the transmission request is received within a predetermined time after the transmission request is transmitted, the determination unit 23 indicates that the connection is being established in the connection state value stored in the information table 253 in the holding unit 25. Write information. On the other hand, if the acknowledgment for the transmission request is not received within a predetermined time after the transmission request is transmitted, the determination unit 23 sets the connection state value stored in the information table 253 to information indicating unconnected. Write.

In addition, the determination unit 23 refers to the reception data output from the wireless unit 21 when the transmission unit 22 outputs that the data has been transmitted, and is transmitted within a predetermined time after the data is transmitted. It is determined whether an acknowledgment for the received data has been received. Here, when the acknowledgment is not received within a predetermined time after the data is transmitted, the transmission unit 22 retransmits the data. For this reason, the communication speed of data transmitted from the transmission unit 22 to the communication device 12 decreases according to the number of times per unit time in which an acknowledgment for the transmitted data has not been received.

The determination unit 23 calculates the communication speed of data transmitted from the transmission unit 22 to the communication device 12 based on whether or not an acknowledgment for the data is received until the communication end is output from the transmission unit 22. When the communication speed is equal to or higher than the predetermined value, information indicating the predetermined value or higher is written in the communication speed value stored in the information table 253 in the holding unit 25. On the other hand, when the communication speed is less than the predetermined value, the determination unit 23 writes information indicating the less than the predetermined value in the communication speed value stored in the information table 253 in the holding unit 25.

The changing unit 24 refers to the information table 253 in the holding unit 25 when the own device is activated, and acquires information on the order of the own device. Then, the change unit 24 refers to the change table 252 in the holding unit 25, specifies the range of the order including the order of the own device, and acquires the group number associated with the specified range of the order. . The group number acquired from the change table 252 by the changing unit 24 is the group number of the group to which the own device belongs. Then, the change unit 24 instructs the transmission unit 22 to have a predetermined duty ratio (for example, 100% duty ratio). Thereby, the transmission part 22 drives the radio | wireless part 21 with a predetermined | prescribed duty ratio in the initial state immediately after starting of an own apparatus.

When the change unit 24 outputs that the transmission request has been transmitted from the transmission unit 22, the value of the connection state stored in the information table 253 after a predetermined time has elapsed since the transmission request was transmitted. Refer to When the connection state value is information indicating unconnected, the changing unit 24 refers to the change table 252 and obtains the pattern number and the second offset associated with the group number of the group to which the own device belongs. To do.

Then, the change unit 24 refers to the pattern table 250 and selects one of the combinations of the duty ratio and the first offset associated with the pattern number acquired from the change table 252. To do. The changing unit 24 randomly selects one of the combinations of the duty ratio and the first offset associated with the pattern number acquired from the change table 252, for example, at random.

Then, the change unit 24 outputs the combination of the selected duty ratio and the first offset to the transmission unit 22 together with the second offset acquired from the change table 252. The transmission unit 22 offsets the start timing of the repetition cycle of the own device by the second offset output from the changing unit 24. Then, the transmission unit 22 controls the driving and stopping of the radio unit 21 according to the duty ratio and the first offset output from the changing unit 24 in the repeated cycle of the offset device itself, and the radio unit 21 is driven. Send a transmission request within the specified period. In the conventional BLE communication, when the frequencies used by a plurality of slave units overlap, unless one of the slave units performs hopping and the overlap of the frequencies is released, data collision cannot be avoided. . However, according to the present embodiment, since the slave unit changes the duty ratio or the offset based on the success or failure of data transmission, the probability of data collision can be reduced.

On the other hand, when the connection state value is information indicating that the connection is in progress, the changing unit 24 refers to the communication speed value stored in the information table 253. When the communication speed value is information indicating that the value is less than the predetermined value, the changing unit 24 refers to the change table 252 and determines the pattern number and the second offset associated with the group number of the group to which the own device belongs. get. Then, the change unit 24 refers to the pattern table 250 and selects one of the combinations of the duty ratio and the first offset associated with the pattern number acquired from the change table 252. To do.

Then, the change unit 24 outputs the combination of the selected duty ratio and the first offset to the transmission unit 22 together with the second offset acquired from the change table 252. The transmission unit 22 controls the driving and stopping of the radio unit 21 according to the duty ratio, the first offset, and the second offset output from the changing unit 24, and data is transmitted within the period during which the radio unit 21 is driving. Send. Thereby, the probability that the data transmitted from the communication apparatus 20 and the signal transmitted from the other communication apparatus 20 collide can be reduced, and the communication speed can be improved.

The accepting unit 27 accepts information such as the BD address, order, and total number of the own device from an external device, and writes the accepted information in the information table 253 in the holding unit 25. Information such as the BD address, order, and total number is input to the communication device 20 at a predetermined timing when a plurality of communication devices 20 used in a predetermined area such as an event venue are shipped, for example.

The creation unit 26 refers to the holding unit 25 when the communication apparatus 20 is activated, and creates the change table 252 and stores it in the holding unit 25 when the change table 252 is not held in the holding unit 25. When creating the change table 252, the creating unit 26 first refers to the information table 253 in the holding unit 25 and acquires the order of the own device and the total number of communication devices 20. Then, the creation unit 26 refers to the division table 251 in the holding unit 25, identifies a total range including the total number of communication devices 20 acquired from the information table 253, and associates the range with the identified total range. Specify the number of divisions.

Next, the creation unit 26 divides the total number of communication devices 20 acquired from the information table 253 into a plurality of groups having the specified number of divisions. For example, the creation unit 26 divides the plurality of communication devices 20 into a plurality of groups so that the difference in the number of communication devices 20 belonging to the group is 1 or less. Then, the creation unit 26 assigns a group number to each group. Then, the creating unit 26 assigns an order to each communication device 20 included in the total number, and specifies the range of the order of the communication devices 20 belonging to each group according to the number of the communication devices 20 belonging to each group.

Next, the creation unit 26 refers to the pattern table 250 and assigns any pattern number to each group. In the present embodiment, the creation unit 26 assigns a different pattern number to each group. Then, the creation unit 26 refers to the division table 251 and acquires the second offset for each group associated with the total number range including the total number of communication devices 20 acquired from the information table 253.

Next, the creation unit 26 includes the total number of communication devices 20, the number of divisions, the group number of each group, the range of the order of the communication devices 20 belonging to each group, the pattern number assigned to each group, and the number assigned to each group. The change table 252 in which the offset of 2 is associated is created. Then, the creation unit 26 stores the created change table 252 in the holding unit 25.

[Create change table]
FIG. 9 is a flowchart illustrating an example of the creation process of the change table 252. For example, when the communication apparatus 20 is activated, the communication apparatus 20 starts a process of creating the change table 252 illustrated in FIG. Prior to the flowchart shown in FIG. 9, a pattern table 250, a division table 251, and an information table 253 are held in the holding unit 25.

First, the creation unit 26 refers to the holding unit 25 and determines whether or not the change table 252 is already created by determining whether or not the change table 252 is held in the holding unit 25 ( S100). If the change table 252 has already been created (S100: Yes), the communication device 20 ends the creation process of the change table 252 shown in this flowchart.

On the other hand, when the change table 252 is not created (S100: No), the creation unit 26 refers to the information table 253 in the holding unit 25 and acquires the order of the own device and the total number of the communication devices 20 ( S101). Then, the creation unit 26 refers to the division table 251 in the holding unit 25, identifies a total range including the total number of communication devices 20 acquired from the information table 253, and associates the range with the identified total range. The number of divisions is specified (S102).

Next, the creation unit 26 divides the total number of communication devices 20 acquired from the information table 253 into a plurality of groups corresponding to the specified number of divisions (S103). Then, the creating unit 26 assigns a group number to each group, and specifies the range of the order of the communication devices 20 belonging to each group. Then, the creating unit 26 refers to the pattern table 250 and assigns any pattern number to each group (S104).

Next, the creation unit 26 refers to the division table 251 and acquires the second offset for each group associated with the total number range including the total number of communication devices 20 acquired from the information table 253. Then, the creating unit 26 creates the change table 252 by associating the total number, the number of divisions, the group number, the order range, the pattern number, and the second offset (S105). Then, the creation unit 26 stores the created change table 252 in the holding unit 25 (S106). And the communication apparatus 20 complete | finishes the creation process of the change table 252 shown to this flowchart.

[Communication management processing]
FIG. 10 is a flowchart illustrating an example of the communication management process. For example, at the time of activation, the communication device 20 starts the communication management process illustrated in FIG. 10 and monitors the BLE communication executed by the wireless unit 21 and the transmission unit 22.

First, the determination unit 23 determines whether or not a transmission request has been transmitted by determining whether or not the transmission unit 22 has output that a transmission request has been transmitted (S200). When the transmission request is not transmitted (S200: No), the determination unit 23 executes the process shown in step S208.

On the other hand, when the transmission request is transmitted (S200: Yes), the determination unit 23 refers to the reception data output from the wireless unit 21 and confirms the transmission request within a predetermined time after the transmission request is transmitted. It is determined whether a response has been received (S201). If the acknowledgment for the transmission request is not received within a predetermined time after the transmission request is transmitted (S201: No), the determination unit 23 sets the connection state value stored in the information table 253 to the unconnected state. Is written (S203). And the determination part 23 performs the process shown to step S200 again.

On the other hand, when an affirmative response to the transmission request is received within a predetermined time after the transmission request is transmitted (S201: Yes), the determination unit 23 stores the connection state stored in the information table 253 in the holding unit 25. Information indicating that the connection is in progress is written in the value (S202). Then, the determination unit 23 refers to the reception data output from the wireless unit 21 and communicates data transmitted from the transmission unit 22 to the communication device 12 based on whether or not an acknowledgment is received for the transmitted data. Calculate the speed. Then, the determination unit 23 determines whether or not the calculated communication speed is equal to or higher than a predetermined value (S204).

When the communication speed is equal to or higher than the predetermined value (S204: Yes), the determination unit 23 writes information indicating the predetermined value or higher to the communication speed value stored in the information table 253 in the holding unit 25 (S205). Then, the process shown in step S207 is executed. On the other hand, when the communication speed is less than the predetermined value (S204: No), the determination unit 23 writes information indicating less than the predetermined value to the communication speed value stored in the information table 253 in the holding unit 25 ( S206).

Next, the determination unit 23 determines whether or not the communication with the communication device 12 is ended by determining whether or not the communication end is output from the transmission unit 22 (S207). When the communication with the communication device 12 has not ended (S207: No), the determination unit 23 executes the process shown in step S204 again.

On the other hand, when the communication with the communication device 12 is completed (S207: Yes), the determination unit 23 determines whether or not the communication device 20 is powered off (S208). When the power of the communication device 20 is not turned off (S208: No), the determination unit 23 executes the process shown in step S200 again. On the other hand, when the power of the communication device 20 is turned off (S208: Yes), the communication device 20 ends the communication management process shown in this flowchart.

[Control processing of driving period of wireless unit 21]
FIG. 11 is a flowchart illustrating an example of a control process for the driving period of the wireless unit 21. For example, when the communication device 20 is activated, the communication device 20 starts a control process for the driving period of the wireless unit 21 shown in FIG. Prior to the flowchart shown in FIG. 11, a pattern table 250, a division table 251, a change table 252, and an information table 253 are held in the holding unit 25.

First, the changing unit 24 refers to the information table 253 in the holding unit 25 and acquires information on the order of the own device. Then, the changing unit 24 refers to the change table 252 in the holding unit 25, specifies the range of the order including the order of the own device, and sets the group number associated with the specified order range to the own device. Get as the group number. And the change part 24 instruct | indicates a predetermined | prescribed duty ratio to the transmission part 22 (S300). In the present embodiment, the changing unit 24 instructs the transmitting unit 22 to have a duty ratio of 100%, for example.

Next, the changing unit 24 determines whether or not a transmission request has been transmitted to the communication device 12 by determining whether or not the transmission unit 22 has output that a transmission request has been transmitted (S301). When the transmission request is not transmitted to the communication device 12 (S301: No), the changing unit 24 executes the process shown in step S309.

On the other hand, when a transmission request is transmitted to the communication device 12 (S301: Yes), the changing unit 24 determines the connection state value stored in the information table 253 after a predetermined time has elapsed since the transmission request was transmitted. Refer to Then, the changing unit 24 determines whether or not the connection state value is information indicating that the connection is being established (S302).

When the connection state value is information indicating no connection (S302: No), the changing unit 24 refers to the change table 252, and the pattern number and the second offset associated with the group number of the own device. To get. Then, the change unit 24 refers to the pattern table 250 and selects one of the combinations of the duty ratio and the first offset associated with the pattern number acquired from the change table 252. (S303).

Next, the changing unit 24 outputs the combination of the selected duty ratio and the first offset to the transmitting unit 22 together with the second offset, so that the period corresponding to the selected duty ratio and the first offset. The transmission unit 22 is instructed to transmit the data (S304). And the change part 24 performs the process shown to step S301 again. The transmission unit 22 controls the driving and stopping of the radio unit 21 according to the duty ratio, the first offset, and the second offset instructed from the changing unit 24, and transmits within the period during which the radio unit 21 is driving. Send a request.

On the other hand, when the value of the connection state is information indicating that the connection is being established (S302: Yes), the changing unit 24 refers to the value of the communication speed stored in the information table 253 and determines whether the communication speed is equal to or higher than a predetermined value. Is determined (S305). When the communication speed is less than the predetermined value (S305: No), the changing unit 24 refers to the change table 252 and acquires the pattern number and the second offset associated with the group number of the own device. Then, the change unit 24 refers to the pattern table 250 and selects one of the combinations of the duty ratio and the first offset associated with the pattern number acquired from the change table 252. (S306).

Next, the changing unit 24 outputs the combination of the selected duty ratio and the first offset to the transmitting unit 22 together with the second offset, so that the period corresponding to the selected duty ratio and the first offset. Is transmitted to the transmitter 22 (S307). And the change part 24 performs the process shown to step S308. The transmission unit 22 controls the driving and stopping of the radio unit 21 according to the duty ratio, the first offset, and the second offset instructed from the changing unit 24, and data is transmitted within the period during which the radio unit 21 is driving. Send.

On the other hand, if the communication speed is equal to or higher than the predetermined value (S305: Yes), the changing unit 24 determines whether or not the communication with the communication device 12 is ended by determining whether or not the communication end is output from the transmitting unit 22. It is determined whether or not (S308). When the communication with the communication device 12 has not ended (S308: No), the changing unit 24 executes the process shown in step S305 again.

On the other hand, when the communication with the communication device 12 is completed (S308: Yes), the changing unit 24 determines whether or not the power of the communication device 20 is turned off (S309). When the power of the communication device 20 is not turned off (S309: No), the changing unit 24 executes the process shown in step S301 again. On the other hand, when the power supply of the communication device 20 is turned off (S309: Yes), the communication device 20 ends the control process for the driving period of the wireless unit 21 shown in this flowchart.

[hardware]
FIG. 12 is a diagram illustrating an example of hardware of the communication device 20. For example, as illustrated in FIG. 12, the communication device 20 includes a wireless communication module 200, a processor 201, a RAM 202, a flash ROM 203, and an antenna 28.

The transmission unit 22, the determination unit 23, the change unit 24, the creation unit 26, and the reception unit 27 are realized by a processor 201 such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor). The wireless unit 21 is realized by the wireless communication module 200, for example. The holding unit 25 is realized by, for example, a RAM (Random Access Memory) 202 and a flash ROM (Read Only Memory) 203.

The flash ROM 203 stores a communication program. The processor 201 reads out and executes the communication program from the flash ROM 203, thereby realizing the functions of the transmission unit 22, the determination unit 23, the change unit 24, the creation unit 26, and the reception unit 27.

Note that not all communication programs in the flash ROM 203 are necessarily stored in the flash ROM 203 from the beginning. For example, the program is stored in a portable recording medium such as a memory card inserted into the communication device 20, and the communication device 20 acquires and executes a part of the communication program used for processing from the portable recording medium. It may be. In addition, the communication device 20 may acquire and execute the communication program from another computer or server device that stores the communication program via a wireless communication line, a public line, the Internet, a LAN, a WAN, or the like. .

The embodiment has been described above. As is clear from the above description, according to the communication system 10 of this embodiment, each communication device 20 operating as a slave has not received an acknowledgment for a transmission request transmitted to the communication device 12 within a predetermined time. In this case, the time zone for driving the radio unit 21 is changed spontaneously. Thereby, in the communication system 10 in which a plurality of communication devices 20 operating as slave units communicate with one master unit using the same frequency, collision of data transmitted from each communication device 20 can be suppressed. It becomes possible.

For example, each communication device 20 voluntarily changes the duty ratio for driving the radio unit 21 when an acknowledgment for the transmission request transmitted to the communication device 12 is not received within a predetermined time. Thereby, each communication apparatus 20 can reduce the probability that the transmission request transmitted from the own apparatus and a signal transmitted from another communication apparatus 20 collide.

In addition, each communication device 20 voluntarily controls the timing for starting the driving of the radio unit 21 when the acknowledgment to the transmission request transmitted to the communication device 12 is not received within a predetermined time. Change the offset. Thereby, each communication apparatus 20 can reduce the probability that the transmission request of the own apparatus and the signal of the other communication apparatus 20 collide.

Further, a change table 252 is held in the holding unit 25 of each communication device 20. Thereby, the changing unit 24 of each communication device 20 can easily change the combination of the duty ratio and the first offset assigned to the group to which the own device belongs.

Also, a pattern table 250 is held in the holding unit 25 of each communication device 20. Thereby, the changing unit 24 of each communication device 20 can easily select the combination of the duty ratio and the first offset.

Moreover, the start timing of the repetition period of each group is offset by a second offset for each group. Thereby, the communication apparatus 20 which belongs to each group can reduce the probability that the transmission request | requirement of an own apparatus and the signal of the communication apparatus 20 which belongs to another group will collide.

Each communication device 20 includes a creation unit 26 and a reception unit 27. Further, the holding unit 25 holds a division table 251. Then, the creating unit 26 creates the change table 252 based on the total number of communication devices 20 received by the receiving unit 27 and the order of the own devices and the division table 251. Thereby, the manufacturer etc. of each communication apparatus 20 can save the effort which prepares beforehand the change table 252 which the communication apparatus 20 hold | maintains for every communication apparatus 20. FIG.

[Others]
The disclosed technology is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist. For example, in the above-described embodiment, each communication device 20 creates the change table 252 if the change table 252 is not stored in the holding unit 25 at the time of activation, but the disclosed technique is not limited thereto. For example, the change table 252 in the holding unit 25 is created in advance for each communication device 20 by a device different from the communication device 20 and held in each communication device 20 at a predetermined timing such as when the communication device 20 is shipped. It may be written in the part 25.

In the above-described embodiment, the changing unit 24 sets the combination of the duty ratio and the first offset when no acknowledgment is received from the communication device 12 within a predetermined time after the transmission request or data is transmitted. Although it selects at random, the technique of an indication is not restricted to this. For example, the changing unit 24 sequentially selects a combination of the duty ratio and the first offset from the combination of the duty ratio and the first offset in descending order of the duty ratio and the first offset. Also good.

DESCRIPTION OF SYMBOLS 10 Communication system 20 Communication apparatus 21 Radio | wireless part 22 Transmitter 23 Determination part 24 Change part 25 Holding part 250 Pattern table 251 Division | segmentation table 252 Change table 253 Information table 26 Creation part 27 Reception part 28 Antenna

Claims

In the communication device used in a communication system in which a plurality of communication devices that operate as slave units communicate with one master unit using the same frequency,
A transmission unit that transmits a transmission request to the master unit within a data transmission possible period;
A determination unit that determines whether or not an acknowledgment to the transmission request is received within a predetermined time after the transmission unit transmits the transmission request;
A changing unit that changes a duty ratio that is a ratio of the transmittable period to a predetermined period based on a determination result by the determination unit;
Have
The transmitter is
When the duty ratio is changed by the changing unit, the communication apparatus transmits the transmission request to the base unit within the transmittable period corresponding to the changed duty ratio.
The changing unit is
The first offset indicating the time from the start timing of the predetermined period to the start timing of the transmittable period is further changed based on the determination result,
The transmitter is
The transmission request is transmitted to the base unit within the transmittable period starting after the first offset changed by the changing unit has elapsed from the start timing of the predetermined period. The communication apparatus according to 1.
The plurality of communication devices are further divided into a predetermined number of groups, and each of the groups further includes a holding unit that holds a change table in which information indicating the change method of the duty ratio and the first offset is associated with each group. ,
The changing unit is
The duty ratio and the first offset are changed according to information indicating the change method associated with a group to which the device belongs, with reference to the change table. Communication device.
The holding part is
A pattern table that stores a plurality of combinations of the duty ratio and the first offset in association with a pattern number is further retained,
Information indicating the change method is:
Any pattern number stored in the pattern table;
The changing unit is
The pattern number associated with the group to which the own apparatus belongs is extracted from the change table, and any one of the combination of the duty ratio and the first offset associated with the extracted pattern number is the pattern table. 4. The communication device according to claim 3, wherein the current duty ratio and the first offset are changed to the specified duty ratio and the first offset. 5.
In the change table,
A second offset indicating an offset of the start timing of the predetermined period from a reference timing is further associated with each group,
The changing unit is
Referring to the change table, identify the second offset associated with the group to which the device belongs, and notify the transmitter of the identified second offset,
The transmitter is
The start timing of the predetermined period is offset from the reference timing by the second offset notified from the change section, and the offset is changed by the change section with reference to the offset start timing of the predetermined period. The communication apparatus according to claim 4, wherein the transmission request is transmitted to the parent device within the transmittable period corresponding to the duty ratio and the first offset.
The holding part is
In association with the range of the total number of the plurality of communication devices, the communication device further holds a division table in which the number of divisions of the group and the second offset for each group are stored.
A receiving unit that receives the total number of the plurality of communication devices and the order of the own device when the order is assigned to each of the plurality of communication devices according to a predetermined rule;
Referring to the division table, the division number associated with the range of the total number including the total number received by the reception unit is specified, and the plurality of communication devices are determined according to an order assigned to each of the plurality of communication devices. The communication device is divided into groups of the specified number of divisions, and each of the groups is associated with any pattern number stored in the pattern table to create the change table;
The communication apparatus according to claim 5, further comprising:
The communication device used in a communication system in which a plurality of communication devices operating as slave units communicate with one master unit using the same frequency,
Send a transmission request to the parent device within the data transmission period,
Determining whether an acknowledgment for the transmission request is received within a predetermined time after transmitting the transmission request;
Based on the result of the determination, a process of changing a duty ratio that is a ratio of the transmittable period to a predetermined period is executed,
The process of transmitting the transmission request to the base unit is:
When the duty ratio is changed, the communication method is a process of transmitting the transmission request to the base unit within the transmittable period corresponding to the changed duty ratio.
A first communication device that operates as a base unit;
In a communication system having a plurality of second communication devices that operate as slave units and communicate with the first communication device using the same frequency,
Each of the second communication devices is
A transmission unit that transmits a transmission request to the first communication device within a data transmittable period;
A determination unit that determines whether or not an acknowledgment to the transmission request is received within a predetermined time after the transmission unit transmits the transmission request;
A changing unit that changes a duty ratio that is a ratio of the transmittable period to a predetermined period based on a determination result by the determination unit;
Have
The transmitter is
When the duty ratio is changed by the changing unit, the transmission request is transmitted to the first communication device within the transmittable period corresponding to the changed duty ratio.