JP2012175430A - Radio communication system - Google Patents

Abstract

A wireless communication system further reducing power consumption of a slave unit is provided.
Communication between a parent device A1 and a child device B includes regular communication performed during a regular communication period assigned to each child device B, and a child device B having communication data outside the regular communication time zone. There is irregular communication performed by. The subunit | mobile_unit B is provided with the radio | wireless communication part 21, the communication time zone judgment part 24, and the calculating part 26. The wireless communication unit 21 communicates with the parent device A1. The communication time zone determination unit 24 determines the regular communication period assigned to the own device within the regular communication time zone and also determines the start time of the irregular communication time zone. The computing unit 26 causes the wireless communication unit 21 to perform regular communication during the regular communication period determined by the communication time zone determining unit 24, and performs communication by the wireless communication unit 21 within the regular communication time zone other than the regular communication period. And the irregular communication by the wireless communication unit 21 is performed in the irregular communication time zone determined by the communication time zone determination unit 24.
[Selection] Figure 1

Description

  The present invention relates to a wireless communication system.

  Conventionally, there has been a wireless communication system including a parent device connected to a network and a plurality of child devices (see, for example, Patent Document 1). In this wireless communication system, the slave unit performs wireless communication with the master unit and is connected to the network via the master unit.

JP 2005-86776 A

  The slave unit of the wireless communication system described in the above patent document operates using a battery as a power source, and there is a problem that it is desired to reduce the power consumption of the receiving circuit.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a wireless communication system in which the power consumption of the slave unit is further reduced.

  In order to solve the above-described problem, the wireless communication system of the present application includes a parent device and a plurality of child devices to which a communication number indicating a communication order is assigned. Communication between the master unit and the slave unit consists of regular communication in the regular communication time zone consisting of a set of regular communication periods assigned to each slave unit, and the slave unit with communication data is carrier sense outside the regular communication time zone. And irregular communication in an irregular communication time zone in which communication is performed if no collision is detected. The parent device includes a first communication unit that performs communication with the child device. The slave unit includes a second communication unit, a regular communication period determination unit, an irregular communication period determination unit, and a communication control unit. The second communication unit communicates with the parent device. The regular communication period determination unit determines a regular communication period assigned to the own device within the regular communication time zone. The irregular communication period determination unit determines the start time of the irregular communication time zone. The communication control unit causes the second communication unit to perform regular communication during the regular communication period determined by the regular communication period determination unit, and stops communication by the second communication unit within the regular communication time zone except for the regular communication period. And the irregular communication by a 2nd communication part is performed in the irregular communication time slot | zone judged by the irregular communication period judgment part.

  In this wireless communication system, it is also preferable that continuous communication numbers are assigned to the plurality of slave units, and the plurality of slave units perform regular communication in the order of the communication numbers in the regular communication time zone. The regular communication period determination unit determines the regular communication period allocated to the own device within the regular communication time zone based on the communication number assigned to the own device and the regular communication period per slave unit.

  In this wireless communication system, the master unit includes a number detection unit that detects the number of slave units communicating with the master unit, and the first communication unit transmits the number detected by the number detection unit to the slave unit. Yes. Then, the slave unit irregular communication period determination unit determines the irregular communication period based on the start time of the regular communication period, the number of units transmitted from the master unit, and the regular communication period per slave unit. It is also preferable to determine the start time.

  In this wireless communication system, continuous communication numbers are assigned to a plurality of slave units, and in a non-scheduled communication time zone, the plurality of slave units perform irregular communication in the order corresponding to the communication number of the own device. It is also preferable.

  In this radio communication system, the irregular communication period determination unit of the slave unit determines the start time of the irregular communication time zone, the communication time required for one irregular communication, and the communication number assigned to the own device. Based on this, it is also preferable to determine an irregular communication period in which the own device performs irregular communication within the irregular communication time zone, and to perform irregular communication when the irregular communication period comes.

  In this wireless communication system, it is also preferable to add the following configuration. Based on the start time of the irregular communication time zone and the communication time required for one irregular communication, the slave unit irregular communication period determination unit determines the irregular communication period start time for performing irregular communication. The transmission waiting time from the start time of the irregular communication period to the actual start of communication is determined according to the communication number of the own device. The second communication unit performs carrier sense at the timing when the transmission waiting time has elapsed from the start time, and performs irregular communication if no collision is detected.

  According to the present invention, the power consumption of the slave unit can be further reduced.

It is a system configuration figure of the radio communications system of this embodiment. It is the schematic of the management system to which the same is applied. (A)-(c) is a time chart explaining the communication operation same as the above. It is a flowchart explaining the initial setting operation | movement same as the above. It is a flowchart explaining regular communication operation | movement same as the above. It is a flowchart explaining the irregular communication operation | movement same as the above.

  Hereinafter, embodiments of the present application will be described with reference to the drawings.

  FIG. 2 shows an example in which the wireless communication system of this embodiment is applied to a management system that collects and manages the breeding status of grazing livestock (for example, cattle) by wireless communication.

  This wireless communication system includes a parent device A1 and a plurality of (for example, a maximum of 100) child devices B1 ... B100. In the present embodiment, the maximum number of slave units B1... B100 is 100. However, the number of slave units is not limited to 100, and the number may be increased or decreased depending on the usage. Further, in the following description, when a general description of a child device is given, it is expressed as a child device B, and when each child device is described, it is expressed as a child device B1, a child device B2,.

  The child B is attached to the livestock C, for example, by hanging it on the neck of the livestock C. The breeding data of the livestock C is collected by a sensor, and the collected breeding data is periodically transmitted to the parent machine A1.

  The parent device A1 is installed in a pasture where the livestock C is grazed, performs wireless communication with a plurality of child devices B in the communicable range, and receives the breeding data transmitted from each child device B. accumulate. In FIG. 2, only one master unit A1 is shown. However, when the movement range of the livestock C is wider than the communicable range of the master unit A1, a repeater is provided to cover the movement range of the livestock C. One or more may be installed and hopped by a repeater.

  Next, the configuration of the parent device A1 and the child device B will be described with reference to the block diagram of FIG.

  The parent device A1 includes a wireless communication unit 11, which is a first communication unit, a time measuring unit 12, a storage unit 13, and a calculation unit 14, as main components.

  The wireless communication unit 11 includes, for example, a specific low power wireless module, and performs wireless communication with a plurality of slave units B.

  The timer 12 measures the current time, and the time measured by the timer 12 becomes a reference time (system time) for operating each slave unit B in conjunction.

  The storage unit 13 is composed of, for example, a RAM whose power is backed up or a rewritable nonvolatile memory. The storage unit 13 is within the communicable range of the own device, and indicates the identification number (for example, private address or MAC address) assigned to the child device B communicating with the own device, and the communication order of each child device B A communication number and transmission data (for example, breeding data) from each child unit B are stored. The storage unit 13 has a capacity capable of storing breeding data for a certain period. When the free capacity decreases, new breeding data can be stored by overwriting old breeding data.

  The calculating part 14 consists of CPU, for example, and performs the whole control of parent machine A1. In addition, the calculation unit 14 has a function as a number detection unit that detects the number of slave units B that can communicate with the own unit based on the communication result of the wireless communication unit 11, and determines the number of connected slave units B. When detected, the wireless communication unit 11 transmits to all the slave units B.

  The parent device A1 has the above-described configuration. When the data transmitted from the child device B is received at a predetermined time interval, the received data is stored in the storage unit 13, and the child device B The measured data (for example, breeding data of livestock C) is managed.

  The slave unit B includes a wireless communication unit 21, a time measurement unit 22, a storage unit 23, a communication time zone determination unit 24 (a regular communication period determination unit, an irregular communication period determination unit), and a measurement unit. 25 and a calculation unit 26 (communication control unit).

  The wireless communication unit 21 includes, for example, a specific low power wireless module, and performs wireless communication with the parent device A1.

  The timer unit 22 keeps the current time, and when the system time is transmitted from the parent device A1, the time of the own device is made to coincide with the system time.

  The storage unit 23 includes, for example, a RAM whose power is backed up or a rewritable nonvolatile memory. The storage unit 23 includes its own identification number (for example, private address) and communication number, and the number of slave units B transmitted from the master unit A1. Alternatively, measurement data (for example, breeding data of livestock C) measured by the measurement unit 25 described later is stored. Note that the identification number of the slave unit B may be set in advance with a dip switch or the like.

  The communication time zone determination unit 24 includes a regular communication time zone W2 in which all the slave units B perform regular communication with the master unit A1, and any slave unit B that needs to communicate other than the regular communication. Determines an irregular communication time zone W3 for irregularly communicating with the parent device A1 (see FIG. 3). Here, the time lengths of the regular communication time zone W2 and the irregular communication time zone W3 vary depending on the number of slave units B, but the total time W1 of the regular communication time zone W2 and the irregular communication time zone W3 is constant. It is time for. Therefore, the regular communication time zone W2 and the irregular communication time zone W3 are repeated at a constant cycle W1.

  The measuring unit 25 includes sensors for measuring various breeding data such as ecological information of the livestock C and data related to the breeding environment of the livestock C (for example, temperature and humidity), and the measurement results are accumulated in the storage unit 23.

  The computing unit 26 is composed of, for example, a CPU and performs overall control of the slave unit B.

  The subunit B has the above-described configuration, accumulates measurement data measured by the measurement unit 25 at a predetermined sampling interval in the storage unit 23, and accumulates in the storage unit 23 at a predetermined transmission interval. The measured data is transmitted to the parent device A1. Moreover, the subunit | mobile_unit B operate | moves using a battery (not shown) as a power supply.

  Next, communication performed between the parent device A1 and the child devices B (B1... B100) will be described below.

  The parent device A1 periodically collects data from the child device B. For communication performed between the parent device A1 and the child device B, the regular communication in the regular communication time zone W2 and the regular communication are performed. There is irregular communication performed irregularly outside the time zone W2. Here, in the regular communication time zone W2, all the slave units B communicate during the regular communication period assigned to each slave unit B, and the regular communication time zone W2 is assigned to all the slave units B. A set of regular communication periods. In the irregular communication time zone W3, only the slave unit B that wants to perform irregular communications other than the regular communication time zone W2 (for example, the slave unit B with unsent data that failed to be transmitted in the regular communication time zone W2) This is a time zone in which communication with the parent device A1 is performed irregularly.

  FIG. 3A shows a case where, for example, 100 slave units B1... B100 communicate with the master unit A1, and 00:00 and 30:00 of each time are in the regular communication time zone W2. Start time. The communication occupation period when one slave unit B performs regular communication once is within 7 seconds, for example, and 9 seconds is assigned as the regular communication period of one slave unit B, for example. That is, 7 seconds out of 9 seconds in the regular communication period are used for actual communication. Note that one communication occupation period (7 seconds) and regular communication period (9 seconds) are examples, and can be appropriately changed according to the communication speed, the communication data amount, and the like.

  In the regular communication time zone W2, the regular communication period in which each slave unit B performs regular communications is determined by the communication number assigned to each slave unit B by the master unit A1. In the initial setting, the parent device A1 assigns a communication number indicating the communication order to all the child devices B that can communicate with the own device. This communication number starts from 0, and the number increases by 1 according to the communication order.

  Here, if the communication number of a certain slave unit B is n (n is a natural number including 0) and the start time of the regular communication time zone W2 is ts0, the start time ts1 of the regular communication period of the slave unit B is This is expressed by the equation (1), and 9 seconds from the time ts1 is the regular communication period of the slave unit B.

ts1 = ts0 + n × 9 (seconds) (1)
For example, the slave unit B with the communication number 0 starts periodic transmission at 00: 00 / hour and 3:30 seconds / hour, and the slave unit B with the communication number 95 has 14 minutes / 15 seconds / hour, 44 minutes / hour. Regular communication starts at 15 seconds. In addition, the subunit | mobile_unit B starts a carrier sense from 0.5 second before starting regular transmission, and when detecting the carrier at the start of a regular communication period, continues a carrier sense for another 0.5 second, If the carrier is detected, the regular communication is stopped.

  As described above, since the regular communication period is set to 9 seconds, if the maximum number of slave units B is 100, the regular communication time period W2 is completed within 15 minutes. When the regular communication time zone W2 starts at 00:00, the period from the end of the regular communication time zone W2 until 30:00 becomes the irregular communication time zone W3. When the regular communication time zone W2 starts at 30:00, the period from the end of the regular communication time zone W2 to 60 minutes 00 seconds becomes the irregular communication time zone W3. That is, the regular communication time zone W2 and the irregular communication time zone W3 change depending on the number of slave units B that can communicate with the master unit A1.

  Here, the number of slave units B that can communicate with the master unit A1 is N (N is a positive integer), and the start time of the regular communication time zone W2 is ts0 (for example, 00:00 per hour, 30:00 per hour). Then, the start time ts2 of the irregular communication time zone W3 is expressed by the following equation (2).

ts2 = ts0 + N × 9 (seconds) (2)
For example, if the number N of slave units B that can communicate with the master unit A1 is 50, ts2 = ts0 + 50 × 9 = ts0 + 7 minutes 30 seconds, 7 minutes 30 seconds per hour, and irregular communication at 37 minutes 30 seconds per hour The time zone W3 starts (see FIG. 3B). If the number N of slave units B is 89, ts2 = ts0 + 89 × 9 = ts0 + 13 minutes 21 seconds, and the irregular communication time zone W3 starts at 13 minutes 21 seconds per hour and 43 minutes 21 seconds per hour. (See FIG. 3 (c)).

  Moreover, in the irregular communication time zone W3, the irregular communication period in which the slave unit B performs irregular communication is determined as follows. In addition, the communication occupation period when one slave unit B performs irregular communication once is within 7 seconds, for example, and 9 seconds is assigned as the irregular communication period of one slave unit B, for example. . That is, 7 seconds are assumed to be used for actual communication in 9 seconds of the irregular communication period.

  Here, if the number of slave units B is 50, the irregular communication time zone W3 is a period from 07:30 every hour to 3:30 hours per hour, and from 37:30 hours per hour to 60 minutes 00 seconds per hour ( 0 minutes 00 seconds), and the periods obtained by dividing each period by 9 seconds are each irregular communication period. That is, in the period from 07 minutes 30 seconds per hour to 3:30 hours per hour, the start time of the irregular communication period (that is, the timing at which the slave unit B starts irregular communication) is 07 minutes 30 seconds, 07 minutes 39 seconds, 07 minutes 48 seconds, 07 minutes 57 seconds, etc., and 150 irregular communications are possible within the period. Also, in the period from 37 minutes 30 seconds per hour to 6 hours 00 seconds per hour, the start time of the irregular communication period is 37 minutes 30 seconds, 37 minutes 39 seconds, 37 minutes 48 seconds, 37 minutes 57 seconds, and so on. In this period, 150 irregular communications are possible.

  If the number of slave units B is 89, the irregular communication time zone W3 is a period from 13 minutes 21 seconds per hour to 3:30 hours per hour and 43 minutes 21 seconds per hour to 60 minutes 00 seconds per hour (0 Min 00 sec), and each period divided by 9 seconds is an individual irregular communication period. That is, in the period from 13 minutes 21 seconds per hour to 3:30 seconds per hour, the start time of the irregular communication period is 13 minutes 21 seconds, 13 minutes 30 seconds, 13 minutes 39 seconds, 13 minutes 48 seconds, and so on. Within 111 times, irregular communication is possible. Also, in the period from 43 minutes 21 seconds per hour to 6 minutes 00 seconds per hour, the start time of the irregular communication period is 43 minutes 21 seconds, 43 minutes 30 seconds, 43 minutes 39 seconds, 43 minutes 48 seconds, Within this period, 111 irregular communications are possible.

  In order to suppress the occurrence of collision in each irregular communication period within the irregular communication time zone W3, the timing at which each slave unit B starts data transmission to the master unit A1 is assigned to each slave unit B. It is shifted by 0.01 seconds according to the communication number. That is, when the communication number of a certain slave unit B is n (n is a natural number including 0) and the start time of the irregular communication period is ts3, the timing ts4 at which the slave unit B starts data transmission in the irregular communication period is It is represented by the following formula (3). That is, a transmission waiting time obtained by multiplying the communication number n by 0.01 (seconds) is provided between the start of the irregular communication period and the time when each slave unit B starts irregular transmission.

ts4 = ts3 + n × 0.01 (seconds) (3)
Therefore, assuming that the number of slave units B is 50 and the communication number of the slave unit B to be used for irregular communication is 45, the timing at which the slave unit B transmits data in the irregular communication time zone W3 is 07 minutes. 30 seconds 45, 07 minutes 39 seconds 45, 07 minutes 48 seconds 45... 29 minutes 51 seconds 45. Each slave unit B starts carrier sense 0.5 seconds before starting data transmission, and stops data transmission if there is a collision detection at the start of data transmission. Since the transmission waiting time is shifted by 0.01 seconds in accordance with the communication number n, transmission data collision is less likely to occur. When a certain slave unit B performs irregular communication with the master unit A1 (including a case where data transmission fails), the transmission waiting time is set to the slave unit B in the one irregular communication period immediately after. Then, the transmission waiting time is returned to n × 0.01 (seconds). As described above, in the irregular communication period immediately after the successful irregular communication, the transmission time is set longer than that of the other slave units so that the other slave unit B can preferentially transmit data. I have to.

  Here, the operation of the present system will be described with reference to FIGS.

  FIG. 4 shows the operation when the parent device A1 initially sets the system time, communication number, etc. in the child devices B (B1... B100). For example, after the battery is set in the child device B1 and the power is turned on in the child device B1 (S1), when the initial setting switch provided in the child device B1 is turned on (S2), the child device B1 has its own device. The identification number and the setting request signal are wirelessly transmitted to the parent device A1. When receiving the setting request signal from the slave unit B1, the master unit A1 transmits the system time, the communication number assigned to the slave unit B1, and the number of slave units B to the slave unit B1 (S3). Upon receiving the setting content transmitted from the parent device A1, the child device B1 stores the received setting content in the storage unit 23 (S4), and then transmits an ACK signal (such as its own identification number) to the parent device A1. Return (S5). When the parent device A1 receives the ACK signal from the child device B1, the storage unit 13 stores the identification number of the child device B1 that has been set and the communication number assigned to the child device B1 (S6). On the other hand, if the parent device A1 does not receive the ACK signal within a predetermined time after transmitting the setting content to the child device B1, the setting content is retransmitted to the child device B1 (S7). The slave unit B1 supplies the power to the wireless communication unit 21 and waits for reception until a predetermined retry transmission waiting time elapses after the setting request signal is transmitted to the master unit A1. When the retry transmission waiting time elapses, the wireless communication unit 21 is stopped to suppress power consumption (S8).

  Each time the setting request signal is input from the child device B, the parent device A1 performs the above processing, and the system time, the communication number, and the child device of all child devices B that have issued the setting request signal are processed. Setting data such as the number of units can be set.

  Next, periodic communication between the parent device A1 and the child device B in the regular communication time zone W2 will be described with reference to FIG. The communication time zone determination unit 24 of the slave unit B uses the above equation (1) based on information such as the system time set in the initial setting, the communication number and the number of the own device, and the regular communication time zone. The regular communication period of the own device in W2 is calculated. In the regular communication time zone W2, when the regular communication period of the slave unit B1 comes (S11), the arithmetic unit 26 of the slave unit B1 starts supplying power to the wireless communication unit 21 (S12). And the calculating part 26 reads the breeding data which were measured by the measurement part 25 and was accumulate | stored in the memory | storage part 23, and this breeding data is transmitted from the radio | wireless communication part 21 to parent | base_device A1 (S13).

  When the wireless communication unit 11 of the parent device A1 receives the breeding data from the child device B1, the calculation unit 14 stores the breeding data in the storage unit 13 for each child device (S14), and the wireless communication unit 11 uses the ACK signal. At the same time, the current time (system time) is returned to the transmitting slave unit B1 (S15). When the number of slave units B has increased since the previous communication, the arithmetic unit 14 of the master unit A1 returns the number of slave units B and the current system time together with the ACK signal to the slave unit B.

  When receiving the ACK signal from the parent device A1, the calculation unit 26 of the child device B1 corrects the time of the time measuring unit 22 based on the system time sent together with the ACK signal. When the number of slave units B is sent together with the ACK signal, the arithmetic unit 26 of the slave unit B1 registers the number of slave units B in the storage unit 23 (S16). If the ACK signal from the parent device A1 cannot be received even after a predetermined time has passed after the breeding data is transmitted, the computing unit 26 of the child device B1 retransmits the breeding data from the wireless communication unit 21 to the parent device A1. (S17). And if the calculating part 26 of the subunit | mobile_unit B1 can receive the ACK signal sent back from parent | base_unit A1, the power supply to the radio | wireless communication part 21 will be stopped, and the regular communication period of an own machine will be carried out in the regular communication time slot | zone W2. Other than the above, power consumption is suppressed by stopping power feeding to the wireless communication unit 21. In addition, after the breeding data is transmitted, the calculation unit 26 of the child unit B1 determines that the communication has failed if the ACK signal cannot be received even after a predetermined determination time has elapsed, and supplies power to the wireless communication unit 21. The breeding data that failed to be transmitted is retransmitted in the irregular communication time zone W3. In the other child units B2... B100, when the regular communication period of the own device comes, the same periodical communication processing as in the case of the child unit B1 is performed, and the breeding data is transmitted from the child unit B to the parent unit A1. The master unit A1 returns the system time and the number of slave units B to the slave unit B that is the transmission source.

  Next, irregular communication between the parent device A1 and the child device B in the irregular communication time zone W3 will be described with reference to FIG. The communication time zone determination unit 24 of the slave unit B uses the above-described equation (2) based on information such as the system time and the number of slave units B set in the initial setting, and the irregular communication time zone W3. The start time of is calculated. When the irregular communication time zone W3 is reached (S21), in the slave unit B (for example, slave units B1 and B2) having information to be transmitted to the master unit A1, the calculation unit 26 starts to supply power to the wireless communication unit 21 (S22). ). In a slave unit (eg, slave unit B100) that has no information to be transmitted to the master unit A1, the calculation unit 26 maintains a state in which power supply to the wireless communication unit 21 is stopped (S23).

  In the slave units B1 and B2, the wireless communication unit 21 starts carrier sense (S23). Here, in each irregular communication period in the irregular communication time zone W3, the transmission waiting time of each slave unit B is provided with a time difference corresponding to the communication number as shown by the equation (3). Accordingly, the sub unit B1 having a small communication number starts carrier sense first (S24, S25), and if there is no carrier detection, starts data transmission to the main unit A1 (S26). Further, since the slave unit B1 has already started the irregular communication when the slave unit B2 having the larger communication number starts carrier sense, the arithmetic unit 26 of the slave unit B2 detects the carrier, so that the wireless communication unit The power supply to 21 is stopped (S27).

  When receiving the transmission data (bred data such as ecological information) from the child unit B1, the parent unit A1 stores this breeding data in the storage unit 13 for each child unit, and stores the current time (system time) together with the ACK signal. The data is returned to the transmitting device B1 (S28). When the number of slave units B has increased since the previous transmission, the arithmetic unit 14 of the master unit A1 returns the number of slave units B and the current system time together with the ACK signal from the wireless communication unit 11 to the slave unit B. .

  When receiving the ACK signal from the parent device A1, the calculation unit 26 of the child device B1 as the transmission source corrects the time of the time measuring unit 22 based on the system time sent together with the ACK signal. When the number of slave units B is sent together with the ACK signal, the arithmetic unit 26 of the slave unit B1 registers the number of slave units B in the storage unit 23 (S29). Even after the slave unit B1 performs the irregular communication once, when there is still transmission data (S30), the wireless communication unit 21 of the slave unit B1 performs carrier sense again (S31). The transmission waiting time in this case is 100 × 0.01 (seconds) = 1 (seconds) when the number of slave units B is 100. Therefore, the irregular communication of other slave units B is given priority. Done. As a result of carrier sense, if no carrier is detected, the slave unit B1 starts data transmission to the master unit A1 (S32), and stores the system time and the number of slave units returned together with the ACK signal from the master unit A1. And the process ends (S33, S34). After receiving the reply from the parent device A1, if there is no information to be transmitted to the parent device A1, the operation unit 14 of the child device B1 ends the irregular communication and stops the power supply to the wireless communication unit 21. Thus, power consumption is reduced (S35).

  In the slave unit B2 that has data to be transmitted to the master unit A1 by irregular communication, the power supply to the wireless communication unit 21 is stopped in S27, and then power is supplied to the wireless communication unit 21 again when a predetermined pause time has elapsed. Then, the wireless communication unit 21 is caused to start carrier sense (S37). If the carrier is detected as a result of the carrier sense, the computing unit 26 of the slave unit B2 stops the power supply to the wireless communication unit 21 (S38). The calculation unit 26 of the slave unit B2 starts supplying power to the wireless communication unit 21 every time the pause time elapses until irregular communication can be performed (S36), and performs carrier sense (S37). If no carrier is detected, data transmission to the parent device A1 is started (S39).

  As described above, the wireless communication system according to the present embodiment includes the parent device A1 and a plurality of child devices B to which communication numbers indicating the communication order are assigned. The communication between the parent device A1 and the child device B is a child that performs regular communication in the regular communication time zone W2 composed of a set of regular communication periods assigned to each child device and irregular communication other than the regular communication time zone W2. The device B performs carrier sense, and includes irregular communication in the irregular communication time zone W3 in which communication is performed if no collision is detected. The parent device A1 includes a wireless communication unit 11 (first communication unit) that performs communication with the child device B. The subunit | mobile_unit B is provided with the radio | wireless communication part 21 (2nd communication part), the communication time zone judgment part 24 (periodic communication period judgment part, irregular communication period judgment part), and the calculating part 26 (communication control part). ing. The wireless communication unit 21 communicates with the parent device A1. The communication time zone determination unit 24 determines the regular communication period assigned to the own device within the regular communication time zone W2, and also determines the start time of the irregular communication time zone W3. The calculation unit 26 causes the wireless communication unit 21 to perform regular communication during the regular communication period, stops communication by the wireless communication unit 21 outside the regular communication period of the own device within the regular communication time zone W2, and irregularly. Irregular communication by the wireless communication unit 21 is performed in the communication time zone W3.

  As a result, each slave unit determines in advance the regular communication period in which its own device performs regular communication. Therefore, the wireless communication unit 21 is operated only during the regular communication period in which its own device performs regular communication, and the slave unit automatically operates in the regular communication time zone. The power supply to the wireless communication unit 21 can be stopped except during the regular communication period of the machine. Therefore, since power supply to the wireless communication unit 21 can be stopped during the regular communication time zone W2 other than the regular communication period of the own device, power consumption can be reduced, and the battery life can be extended when the slave unit B is battery-driven. it can.

  Moreover, in this embodiment, the continuous communication number is assigned to the plurality of slave units B, and the plurality of slave units B perform regular communication in the order of the communication numbers in the regular communication time zone. That is, the communication time zone determination unit 24 of the child device B is assigned to the own device within the regular communication time zone W2 based on the communication number assigned to the own device and the regular communication period per child device. Determine the regular communication period.

  Thereby, the regular communication period of the own device can be obtained by a relatively simple calculation.

  In the present embodiment, the calculation unit 14 of the master unit A1 detects the number of slave units B communicating with the master unit A1, and the wireless communication unit 11 determines the number detected by the calculation unit 14 as a slave unit. Sending to B. Then, in the communication time zone determination unit 24 of the slave unit B, based on the start time of the regular communication time zone W2, the number of units transmitted from the master unit A1, and the regular communication period per slave unit, it is irregular. The start time of the communication time zone W3 is determined. The arithmetic unit 14 of the parent device A1 constitutes a number detection unit that detects the number of child devices B communicating with the parent device A1.

  Thereby, since the irregular communication time zone is obtained based on the result of detecting the number of slave units B, even if the number of slave units B is increased or decreased, the irregular communication time zone can be accurately determined by simple calculation. Can be sought.

  Moreover, in this embodiment, the continuous communication number is allocated to the plurality of slave units B, and in the irregular communication time zone, the plurality of slave units B perform irregular communication in the order corresponding to the communication number of the own device. Is going.

  As a result, the communication by the wireless communication unit 21 can be stopped and the power supply to the wireless communication unit 21 can be stopped outside the period in which the own device performs the irregular communication even in the irregular communication time zone. When the slave unit B is battery-driven, the battery life can be extended.

  In the present embodiment, the communication time zone determination unit 24 of the slave unit B performs irregular communication based on the start time of the irregular communication time zone W3 and the communication time required for one irregular communication. The start time of the irregular communication period is obtained, and the transmission waiting time from the start time of the irregular communication period to the actual start of communication is determined according to the communication number of the own device. And the radio | wireless communication part 21 of the subunit | mobile_unit B performs carrier sense at the timing when the transmission waiting time passed from the start time of irregular communication, and if there is no collision detection, irregular communication is performed.

  Accordingly, the wireless communication unit 21 can be stopped during the irregular communication time zone except for the irregular communication period of the own device, thereby further reducing power consumption. In the present embodiment, a plurality of irregular communication periods are provided in the irregular communication time zone, and any slave unit B may perform irregular communications in each irregular communication period. Since the occurrence of collisions is reduced by shifting the time, collisions are unlikely to occur, and the time required to complete irregular communication can be shortened.

  In the irregular communication time zone, each slave unit B may perform irregular communication in a predetermined communication order as in the regular communication time zone. That is, in the communication time zone determination unit 24 of the slave unit B, based on the start time of the irregular communication time zone W3, the communication time required for one irregular communication, and the communication number assigned to the own device. In the irregular communication time zone W3, an irregular communication period in which the own device performs irregular communication is determined, and irregular communication is performed when the irregular communication period comes.

  Accordingly, the wireless communication unit 21 can be stopped during the irregular communication time zone except for the irregular communication period of the own device, thereby further reducing power consumption.

  In the above-described embodiment, the parent device A1 sets a communication number for each child device B. However, an identification number (such as a private address) assigned to each child device B may be used as the communication number. In that case, there is no need to set a communication number.

  In the above-described embodiment, the communication time zone determination unit 24 of the slave unit B calculates the regular communication period of the own device in the regular communication time zone W2 and the start time of the irregular communication time zone W3. On the device A1 side, the regular communication period of each child device or the start time of the irregular communication time zone W3 may be calculated. That is, in the master unit A, the regular communication period of each slave unit B can be obtained using the above-described equation (1) in the same manner as the slave unit B calculates the regular communication period of its own unit. . Further, in the parent device A, the start time of the irregular communication time zone W3 is calculated using the above equation (2) in the same manner as the slave device B calculates the start time of the irregular communication time zone W3. be able to. Further, in the parent device A, the transmission waiting time from the start time of the irregular communication period can be calculated for each child device using the above equation (3) by the same method as the calculation method by the child device B. Further, in the parent device A, the irregular communication in which each child device B performs irregular communication using the start time of the irregular communication time zone, the communication number, and the time necessary for performing the irregular communication once. The start time of the period can be determined. Then, the parent device A obtains the regular communication period of each child device B obtained by the above calculation, the start time of the irregular communication time zone W3, and the timing at which each child device B starts the irregular communication (irregular communication). The transmission waiting time from the period or the start time of the irregular communication period set for each slave unit) may be transmitted to the slave unit B and set in each slave unit B. No operation on the child unit B side is required.

A1 Master unit 11 Wireless communication unit (first communication unit)
B (B1... B100) Slave unit 21 Wireless communication unit (second communication unit)
24 Communication time zone determination unit (regular communication period determination unit, irregular communication period determination unit)
26 Calculation unit (communication control unit)

Claims (6)

Consists of a master unit and a plurality of slave units assigned communication numbers indicating the communication order,
The communication between the master unit and the slave unit is a regular communication in a regular communication time zone consisting of a set of regular communication periods assigned to each slave unit, and the communication data other than the regular communication time zone is the communication data. Including irregular communication during irregular communication hours when the slave unit communicates,
The parent device includes a first communication unit that performs communication with the child device,
The slave unit includes: a second communication unit that communicates with the master unit; a regular communication period determination unit that determines the regular communication period assigned to the own unit within the regular communication time zone; An irregular communication period determination unit that determines a start time of a regular communication time zone, and a periodical communication by the second communication unit during the regular communication period determined by the regular communication period determination unit, and the regular communication time The communication by the second communication unit is stopped outside the regular communication period within the band, and the irregular communication by the second communication unit is performed during the irregular communication time period determined by the irregular communication period determination unit. A wireless communication system comprising: a communication control unit that performs the operation. A plurality of the slave units are assigned consecutive communication numbers,
In the regular communication time zone, the plurality of slave units perform regular communication in the order of the communication numbers,
The periodic communication period determination unit is configured to allocate the periodic period allocated to the own apparatus within the periodic communication time period based on the communication number allocated to the own apparatus and the periodic communication period per one slave unit. The wireless communication system according to claim 1, wherein a communication period is determined. The master unit includes a number detection unit that detects the number of slave units that communicate with the master unit, and the first communication unit transmits the number detected by the number detection unit to the slave unit. ,
In the irregular communication period determination unit of the slave unit, based on the start time of the regular communication time zone, the number transmitted from the master unit, and the regular communication period per one slave unit, The wireless communication system according to claim 1, wherein a start time of the irregular communication time zone is determined. A plurality of the slave units are assigned consecutive communication numbers,
4. The wireless communication according to claim 1, wherein, in the irregular communication time zone, the plurality of slave units perform irregular communication in an order corresponding to a communication number of the own device. 5. system.   In the irregular communication period determination unit of the slave unit, based on the start time of the irregular communication time zone, the communication time required for one irregular communication, and the communication number assigned to the own device, 5. The wireless communication system according to claim 4, wherein an unscheduled communication period in which the own device performs unscheduled communication within the unscheduled communication time period is determined, and the unscheduled communication is performed when the unscheduled communication period comes. . In the irregular communication period determination unit of the slave unit, an irregular communication period for performing irregular communication based on a start time of the irregular communication time zone and a communication time required for one irregular communication. Determine the start time, determine the transmission waiting time from the start time of the irregular communication period until the actual communication starts according to the communication number of the own machine,
5. The wireless communication system according to claim 4, wherein the second communication unit performs carrier sense at a timing when the transmission waiting time elapses from the start time, and performs irregular communication if no collision is detected.

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