JP4880212B2 - Wireless communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the repetition of data collision between slave units in the system due to a deviation in transmission timings. <P>SOLUTION: A master unit 1 is provided with a reception timing check section 20d. When the reception timing of measurement data from the slave unit is deviated from a permissible range (tLim1 to tLim2) in a time slot assigned to the slave unit of a sender of the measurement data, the reception timing check section 20d instructs the slave unit of the sender to adjust the transmission timing of the measurement data so that the reception timing falls in the permissible range. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a wireless communication system between a parent device and a child device that transmits and receives data wirelessly.

  Conventionally, as this type of wireless communication system, a wireless sensor system as shown in FIG. 17 has been used (see, for example, Patent Document 1). In the figure, 1 (1-1 to 1-n) is a slave unit (transmitter), 2 is a master unit (receiver), 3 is a controller, and the slave unit 1 is connected to the master unit 2 via a wireless line. The As the subunit | mobile_unit 1, wireless sensors, such as a temperature sensor, a humidity sensor, a flow meter, and a watt-hour meter, are used. The master unit 2 receives the measurement data from the slave unit 1 and transfers it to the controller 3. The controller 3 performs control calculation based on the measurement data, and controls air conditioning equipment such as a VAV (variable air volume adjustment unit) and an FCU (fan coil unit).

  In such a wireless communication system, measurement data is transmitted from the slave unit 1 to the master unit 2 at a constant period T in order to perform smooth control without hunting. That is, the slave units 1-1 to 1-n are registered in the master unit 2, thereby providing a parent-child connection relationship (parent-child relationship) between the master unit 2 and the slave units 1-1 to 1-n. The transmission timing is shifted from the slave units 1-1 to 1-n, and the measurement data is periodically sent to the master unit 2. The transmission timing of measurement data from the slave units 1-1 to 1-n is designated by the master unit 2. That is, base unit 2 designates the transmission timing of the measurement data to slave units 1-1 to 1-n so that the reception timings of the measurement data do not overlap.

  The present applicant considers the time slot method as a method of specifying the transmission timing from the parent device 2 to the child devices 1-1 to 1-n. In this time slot method, the base unit 2 divides the cycle T into a plurality of time slots, assigns the time slots in the cycle T to the slave units 1-1 to 1-n, and uses the assigned time slots as measurement data. The slave units 1-1 to 1-n are notified as transmission slots. For example, the period T is divided into m (m> n) time slots S1 to Sm, the time slots S1 to Sn in the period T are assigned to the slave units 1-1 to 1-n, and the assigned time slots S1 to Sn are notified to the slave units 1-1 to 1-n. The subunit | mobile_unit 1 receives the notification of the time slot from the main | base station 2, and transmits measurement data by the notified time slot.

Japanese Patent Laid-Open No. 8-130783

  However, in the time slot method described above, the transmission timing of measurement data from the slave unit 1 may be shifted for some reason. When the transmission timing of measurement data from the slave unit 1 is shifted, the measurement data received by the master unit 2 is out of the time slot assigned to the slave unit 1 and collides with the measurement data from other slave units 1. This collision may occur repeatedly at time intervals of the period T.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide wireless communication capable of preventing repeated collision of data between slave units in the system due to a shift in transmission timing. To provide a system.

In order to achieve such an object, the present invention provides a wireless communication system including a parent device and a child device that wirelessly transmits and receives data to and from the parent device. When a connection request is received from a slave unit, a unit obtained by time-dividing the period T is defined as a time slot, and an arbitrary unused time slot in the period T is assigned to the slave unit, and the slave unit is assigned to the slave unit. Means for notifying the time slot assigned to the time slot from the notification timing of the time slot to the time at the center of the assigned time slot in the next period of the period T, and the data reception timing from the slave unit check whether or not the certain time of the center of the time slots the allowable range determined as the center of the time slot assigned to the transmission source of the slave unit of Means for, when the reception timing of the data is out of tolerance, so that the reception timing of the data is the center of the allowable range, means for instructing an adjustment of the transmission timing of data to the transmission source of the slave unit The slave unit is provided with means for transmitting data to the master unit every period T according to the time slot assigned to the slave unit notified from the master unit.

In the present invention, when the master unit receives a connection request from a slave unit of the wireless communication system to which the master unit belongs, the master unit sets a unit of time division of the period T as a time slot, and any unused time in the period T. The slot is assigned to the slave unit, and the assigned time slot is notified to the slave unit as the time from the notification timing of the time slot to the time at the center of the assigned time slot in the next cycle of cycle T. Further, when the master unit receives data from the slave unit, the master unit checks the reception timing of the data. When the data reception timing is out of the allowable range centered on the time at the center of the time slot in the time slot allocated to the slave device that is the transmission source of the data, the master unit receives the data reception timing. Is instructed to adjust the transmission timing of the data to the slave unit of transmission source so that becomes the center of the allowable range (the time at the center of the time slot) . In accordance with this instruction, the transmission-source child device adjusts the transmission timing of data to the parent device.

  According to the present invention, when the reception timing of data in the master unit deviates from the allowable range in the time slot assigned to the slave unit of the data transmission source, the data from the transmission source slave unit is set within the allowable range. Since the transmission timing is automatically adjusted, it is possible to prevent repeated collision of data between the slave units in the system due to a shift in transmission timing.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a wireless communication system showing an embodiment of the present invention. In this figure, the same reference numerals as those in FIG. 17 denote the same or equivalent components as those described with reference to FIG. 17, and the description thereof will be omitted. In this embodiment, a simple configuration will be described with an example in which the slave unit 1 includes two slave units 1-1 and 1-2 as a system at the start of operation.

  The principal part of the subunit | mobile_unit (transmitter) 1 is shown to Fig.2 (a). The subunit | mobile_unit 1 is provided with the radio | wireless communication control part 1a, the sensor measurement part 1b, the power saving management part 1c, and the transmission timing adjustment part 1d. The wireless communication control unit 1a controls communication with the parent device 2. The sensor measurement unit 1b measures temperature, humidity, and the like, and sends the measurement data to the wireless communication control unit 1a. The power saving management unit 1 c manages power consumption in the slave unit 1. The transmission timing adjustment unit 1 d receives a transmission timing adjustment instruction (described later) from the parent device 2 and adjusts the transmission timing of measurement data from the child device 1 to the parent device 2.

  FIG. 2B shows a main part of the parent device (receiver) 2. The base unit 2 includes a host communication unit 2a, a radio communication control unit 2b, and a measurement data management unit 2c. The upper communication unit 2 a controls communication with the controller 3. The wireless communication control unit 2b controls communication with the handset 1. The measurement data management unit 2c manages measurement data from the slave unit 1 via the wireless communication control unit 2b.

In addition, the subunit | mobile_unit 1 and the main | base station 2 are implement | achieved by the hardware which consists of a processor and a memory | storage device, and the program which implement | achieves various functions in cooperation with these hardware.
In the following, the operation at the start of operation in this system will be described in accordance with the sequence shown in FIG.

[Initial processing]
Now, as a state before the start of operation, it is assumed that the power of the child device 1-1 (# 1), the child device 1-2 (# 2), and the parent device 2 (# 1) is turned off. When the power of the parent device 2 is turned on from this state (FIG. 3: arrow (1)), the parent device 2 starts the initial process (FIG. 3: periods t1 to t2).

  In this initial process, base unit 2 performs carrier sense for the frequency band used in its own communication area during period T. That is, during the period T, it is checked whether or not there is a slave (carrier) that communicates with the master 2 in the used frequency band. Then, based on the result of the carrier sense, a time slot table is created in which one division unit obtained by time division of the period T is a time slot.

  FIG. 4 shows a flowchart of initial processing executed by the base unit 2. When power is turned on, base unit 2 starts counting time of a timer of one period T, and a time slot table (table indicating the use status of time slots) in which one period T is divided into a plurality of time slots. Is set (step 100). Subsequently, base unit 2 sets a timer of one cycle T (step 101), and repeats the time slot table creation process in step 102 until a timeout of the timer of one cycle T is detected in step 103.

  FIG. 6A illustrates the time slot table TB in this case. In the time slot table TB, as will be described later, information on the usage status of each time slot (S1 to S10) in one period T is written. In the initial state, the time slots S1 to S10 are all unused (empty).

  FIG. 5 shows a flowchart of the time slot table creation processing in step 102. In this time slot table creation process, base unit 2 performs carrier sense (step 201), and when a carrier in the used frequency band is detected (YES in step 202), determines whether the carrier is a slave unit of its own system. Confirm (step 203). If it is not a slave unit of its own system (NO in step 203), that is, if it is a slave unit of another system, a busy slot is set (designated) as a time slot at the time of receiving measurement data from that slave unit (step 204). ). If it is a slave unit of the own system (YES in step 203), the time slot at the time of reception of measurement data from the slave unit is set as a time slot in use (step 205).

  In this example, there are no slave units in other systems, and since the slave units 1-1 and 1-2 of the own system are both turned off, no carrier is detected. Therefore, in the time slot table TB created in step 102, the information written in the time slots S1 to S10 does not change as shown in FIG.

[Normal mode]
When the power of the child device 1-1 is turned on (FIG. 3: arrow (2)), the child device 1-1 sends a connection request to the parent device 2 (FIG. 3: arrow (3)). Upon receiving a connection request from the slave unit 1-1 (FIG. 7: YES in step 301), the master unit 2 confirms that the slave unit 1-1 is a slave unit of its own system (YES in step 302). ), It is checked whether or not there is an empty time slot in the time slot table TB (FIG. 6B) (step 303). If it is a connection request from a slave unit of another system, nothing is done (NO in step 302). On the other hand, when the measurement data is received from the slave unit of another system (NO in step 300), the master unit 2 designates the time slot when the measurement data is received from the slave unit as the busy slot (step 308).

  If there is an empty time slot (YES in step 303), master device 2 assigns an arbitrary empty time slot to slave device 1-1 (step 304), and assigns the assigned time slot to slave device 1-1. Notification is made (step 305). If there is no empty time slot (NO in step 303), it is determined that there is an abnormality (step 306), and this is notified to the slave unit 1-1 (step 307).

  In this example, since all of the time slots S1 to S10 are empty, the parent device 2 assigns, for example, the time slot S2 as an arbitrary empty time slot to the child device 1-1 (FIG. 3: arrow (4)). Then, the assigned time slot S2 is notified to the child device 1-1 (FIG. 3: arrow (5)).

  At this time, the parent device 2 writes information indicating that the child device 1-1 is in use in the time slot S2 in the time slot table TB (FIG. 6C). The slave unit 1-1 receives the notification of the time slot S2 from the master unit 2, and transmits measurement data to the master unit 2 in the notified time slot S2 (FIG. 3: arrow (7)). Data transmission is repeated at period T.

  In this embodiment, the notification of the time slot S2 from the parent device 2 to the child device 1-1 is performed by the time ts2 from the notification timing of the time slot S2. In this case, the base unit 2 sets the time at the center of the time slot S2 of the next cycle as tTyp, calculates the time ts2 from the notification timing of the time slot S2 to the handset 1-1 to the time tTyp, and this time ts2 is calculated. Notify the handset 1-1. The slave unit 1-1 receives the notification of the time ts2 from the master unit 2, transmits the measurement data when the time ts2 has elapsed from the notification timing of the time ts2, and repeats the transmission of the measurement data at the period T. .

  When the power of the child device 1-2 is turned on (FIG. 3: arrow (6)), the child device 1-2 sends a connection request to the parent device 2 (FIG. 3: arrow (8)). Base unit 2 receives a connection request from slave unit 1-2 (FIG. 7: YES in step 301), and checks whether there is an empty time slot in time slot table TB (FIG. 6C). (Step 303).

  In this case, all but the time slot S2 are empty, so the base unit 2 assigns, for example, the time slot S5 as an arbitrary empty time slot to the slave unit 1-2 (FIG. 3: arrow (9)), and the assignment The time slot S5 is notified to the handset 1-2 (FIG. 3: arrow (10)). At this time, the parent device 2 writes information indicating that the child device 1-2 is in use in the time slot S5 in the time slot table TB (FIG. 6 (d)). The slave unit 1-2 receives the notification of the time slot S5 from the master unit 2, and transmits the measurement data to the master unit 2 in the notified time slot S5 (FIG. 3: arrow (12)).

[When another slave unit is sending measurement data at the time of connection request]
For example, the power of the handset 1-2 is turned on (FIG. 3: arrow (6)), and at the timing when a request for connection is made from the handset 1-2 to the base unit 2 (FIG. 3: arrow (8)). Unfortunately, the slave unit 1-1 may be transmitting measurement data to the master unit 2.

[Operation example 1]
FIG. 8 shows an operation example 1 when another slave unit is transmitting measurement data at the time of a connection request. In this operation example 1, a slave unit 1-2 sends a connection request to the master unit 2, and at the same time, the slave unit 1-2 starts counting a slot wait timer (soft timer), and the slot wait timer times out. In this case, a retry is made after the elapse of the cycle T.

  In the example of FIG. 8, the measurement data from the slave unit 1-1 and the connection request from the slave unit 1-2 collide (FIG. 8: arrows (7) and (8)), and the master unit 2 has the slave unit 1 No measurement data from -1 nor a connection request from slave unit 1-2 is transmitted. Therefore, time slot allocation is not performed in base unit 2, and time slot notification is not performed from base unit 2 to handset 1-2. For this reason, the slot waiting timer in the child device 1-2 times out.

  When the slot wait timer times out, the slave unit 1-2 waits for the elapse of the period T from the time when the slot wait timer times out, and again makes a connection request to the base unit 2 (FIG. 8: arrow (10)). . In this case, since the transmission timing of the connection request from the slave unit 1-2 is delayed by the time measured by the slot waiting timer from the previous one, the measurement data from the slave unit 1-1 (FIG. 8: arrow (9)) And the connection request from the handset 1-2 (FIG. 8: arrow (10)) do not collide.

  When receiving the connection request from the slave unit 1-2, the master unit 2 assigns, for example, a time slot S5 as an arbitrary empty time slot to the slave unit 1-2 (FIG. 8: arrow (11)), and assigns it. The time slot S5 is notified to the child device 1-2 (FIG. 8: arrow (12)). The slave unit 1-2 receives the notification of the time slot S5 from the master unit 2, and transmits the measurement data to the master unit 2 in the notified time slot S5 (FIG. 8: arrow (14)).

[Operation example 2]
FIG. 9 shows an operation example 2 when another slave unit is transmitting measurement data at the time of a connection request. In this operation example 2, before making a connection request from the child device 1-2 to the parent device 2, carrier sense is performed in the child device 1-2, and when a carrier is detected, the connection request to the parent device 2 is canceled. , Retry after waiting for the period T + α.

  In the example of FIG. 9, since the child device 1-2 detects the child device 1-1 as a carrier (FIG. 9: arrow (8)), carrier sense fails and a connection request to the parent device 2 is not performed. Therefore, the measurement data from the child device 1-1 and the connection request from the child device 1-2 do not collide, and the measurement data from the child device 1-1 is transmitted to the parent device 2 (FIG. 9: arrow). (7)).

  When the slave unit 1-2 cancels the connection request, it waits for the elapse of the cycle T + α from that point and makes a connection request to the master unit 2 again. In this case, since the transmission timing of the connection request from the child device 1-2 is delayed by α from the previous time, the child device 1-1 is not detected as a carrier, and the child device 1-2 is connected to the parent device 2. A request is sent (FIG. 9: arrow (11)).

  When receiving the connection request from the child device 1-2, the parent device 2 assigns, for example, a time slot S5 as an arbitrary empty time slot to the child device 1-2 (FIG. 9: arrow (12)), and assigns it. The time slot S5 is notified to the child device 1-2 (FIG. 9: arrow (13)). The slave unit 1-2 receives the notification of the time slot S5 from the master unit 2, and transmits the measurement data to the master unit 2 in the notified time slot S5 (FIG. 9: arrow (15)).

[Addition of handset]
FIG. 10 shows a sequence in the case where the handset 1-3 (# 3) is added to the system in operation with the power of the handset 1-1 and 1-2 turned on. When the handset 1-3 is added and the power is turned on (FIG. 10: arrow (1)), the handset 1-3 sends a connection request to the base unit 2 (FIG. 10: arrow (3)).

  In response to the connection request from the slave unit 1-3, the master unit 2 assigns, for example, a time slot S9 to the slave unit 1-3 as an arbitrary empty time slot in the time slot table TB (FIG. 6 (d)). (FIG. 10: arrow (4)), the assigned time slot S9 is notified to handset 1-3 (FIG. 10: arrow (5)). At this time, the parent device 2 writes information indicating that the child device 1-3 is in use in the time slot S9 in the time slot table TB (FIG. 12A).

The slave unit 1-3 receives the notification of the time slot S9 from the master unit 2, and transmits the measurement data to the master unit 2 in the notified time slot S9 (FIG. 10: arrow (9)).
If the slave unit 1-1 or 1-2 is transmitting measurement data at the time of a connection request, the slave unit 1-3 transmits a connection request in the same manner as in the operation example 1 and the operation example 2 described above. Change the timing and retry.

[Delete slave unit]
FIG. 11 shows a sequence for deleting the handset 1-2 from the operating system with the power of the handset 1-1 and 1-2 turned on. When the power of the slave unit 1-2 is turned off (FIG. 11: arrow (5)), the master unit 2 displays the elapse of time (monitoring time) TC after receiving the last measurement data from the slave unit 1-2. After waiting, the assignment of the time slot to the child device 1-2 is stopped.

  FIG. 13 shows a flowchart of the slave unit deletion process in the master unit 2. When receiving the measurement data from the slave unit 1-2 (YES in step 401), the master unit 2 starts a slave unit deletion monitoring timer (soft timer) (step 402). If the next measurement data is received from the child device 1-2 before the child device deletion monitoring timer times out (YES in step 403), the child device deletion monitoring timer is cleared (step 406).

  If the slave unit deletion monitoring timer times out (YES in step 404), that is, if the next measurement data is not received from the slave unit 1-2 after the monitoring time TC has elapsed, The assigned time slot S5 is set as an empty time slot (step 405: FIG. 12B).

[Adjustment of measurement data transmission timing from slave unit]
FIG. 14 shows a flowchart of the data transmission timing adjustment process in base unit 2. When receiving the measurement data from the slave unit 1 (step 501), the master unit 2 identifies the time slot assigned to the slave unit 1 (step 502).

  In the present embodiment, an allowable range TS is defined for the time slots S (S1 to S10) as shown in FIG. That is, the time at the center of the time slot S is set to tTyp, and the upper limit time tLim1 is set ahead and the lower limit time tLim2 is set behind this time tTyp.

  For example, it is assumed that the master unit 2 has received measurement data from the slave unit 1-1. In this case, the parent device 2 knows that the time slot S2 is assigned to the child device 1-1 from the time slot table TB (FIG. 6 (d)) at that time. And the reception time of the measurement data from the subunit | mobile_unit 1-1 is checked.

  If the reception time of the measurement data from the child device 1-1 is earlier than the upper limit time tLim1 in the time slot S2 (YES in step 503), the parent device 2 receives the measurement data from the child device 1-1. The slave unit 1-1 is instructed to adjust the transmission timing of the measurement data so that the center time tTyp in the time slot S2 is reached (step 504).

  If the reception time of the measurement data from the child device 1-1 is later than the lower limit time tLim2 in the time slot S2 (YES in step 505), the parent device 2 receives the measurement data from the child device 1-1. The slave unit 1-1 is instructed to adjust the transmission timing of the measurement data so that the center time tTyp in the time slot S2 is reached (step 506).

In accordance with the instruction from the parent device 2, the child device 1-1 approaches or approximates the center time tTyp of the time slot S2 by advancing or delaying the transmission timing of the measurement data by the time designated by the parent device 2 . By adjusting the transmission timing of this, the repetition of collision of the transmission data of the slave unit 1 together in a system according to the shift of the transmission timing is prevented.

  FIG. 16 shows a functional block diagram of the main part of base unit 2. The radio communication control unit 2b of the base unit 2 includes a carrier detection unit 20a, a time slot allocation unit 20b, a time slot allocation prohibition unit 20c, a reception timing check unit 20d, a notification unit 20e, and a time slot table TB. I have. The carrier detection unit 20a includes a first carrier detection unit 20a1 that detects a carrier (child device) of its own system and a second carrier detection unit 20a2 that detects a carrier of another system.

  When the first carrier detection unit 20a1 receives the connection request from the slave unit of its own system, the first carrier detection unit 20a1 sends the connection request to the time slot allocation unit 20b. The time slot assigning unit 20b accesses the time slot table TB, assigns any empty time slot in the time slot table TB to the child device, and notifies the child device via the notification unit 20e of the assigned time slot. To do. In addition, information indicating that the child device is in use is written in the assigned time slot in the time slot table TB.

Further, when the first carrier detection unit 20a1 receives measurement data from the slave unit of its own system, the first carrier detection unit 20a1 sends the reception timing of the measurement data to the reception timing check unit 20d. The reception timing check unit 20d accesses the time slot table TB and knows the time slot assigned to the slave unit that is the transmission source of the measurement data. Then, it is checked whether the reception timing of the measurement data is within the allowable range in the time slot assigned to the transmission source slave unit. If it is out of the allowable range, the reception timing of the measurement data is within the allowable range. Is instructed via the notification means 20e to adjust the transmission timing of data so that it becomes the center (time at the center of the time slot) .

  When the second carrier detection unit 20a2 receives the measurement data from the slave unit of another system, the second carrier detection unit 20a2 sends the reception timing of the measurement data from the slave unit to the time slot allocation prohibition unit 20c. The time slot allocation prohibition unit 20c accesses the time slot table TB, designates the time slot at the time of receiving measurement data from the slave unit as a busy slot, and prohibits the allocation of this busy slot to the slave unit of its own system. .

  In this embodiment, in order to extend the battery life of the handset 1 that operates on a battery, the handset 1 is allowed to perform unidirectional communication as much as possible. When synchronizing with the time slot in communication between the slave unit and the master unit, the slave unit will normally synchronize with the beacon signal etc. emitted by the master unit. Need to be received, and low power consumption cannot be achieved. On the other hand, in the present embodiment, the parent device 2 takes over control for synchronizing the child device 1. Although it is necessary for the slave unit 1 to adjust timing in accordance with an instruction from the master unit 2, the slave unit 1 only needs to instantaneously turn on the reception circuit immediately after data transmission, and a considerable reduction in power consumption can be achieved.

It is a block diagram of the radio | wireless communications system which shows one embodiment of this invention. It is a block diagram which shows the principal part of the main | base station used for this radio | wireless communications system, and a subunit | mobile_unit. It is a sequence diagram which shows the operation | movement at the time of the operation start in this radio | wireless communications system. It is a flowchart of the initial process which a main | base station performs at the time of an operation start. It is a flowchart of a creation process of a time slot table. It is a figure which shows the change of the write information to a time slot table. It is a flowchart of the slot allocation process in the parent machine in the normal mode. It is a sequence diagram which shows the operation example 1 when the other subunit | mobile_unit is transmitting measurement data at the time of a connection request | requirement. It is a sequence diagram which shows the operation example 2 when the other subunit | mobile_unit is transmitting measurement data at the time of a connection request | requirement. It is a sequence diagram in the case of adding a slave unit. It is a sequence diagram in the case of deleting a child machine. It is a figure which shows the change of the write information to the time slot table at the time of adding and deleting a subunit | mobile_unit. It is a flowchart of the deletion processing of the child device in the parent device. It is a flowchart of a data transmission timing adjustment process in the master unit. It is a figure which shows the tolerance | permissible_range of the reception timing of the measurement data defined in a time slot. It is a functional block diagram which shows the principal part of the main | base station in the radio | wireless communications system which concerns on this invention. It is a figure explaining the conventional radio | wireless communications system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 (1-1 to 1-n) ... Slave unit (transmitter), 2 ... Master unit (receiver), 3 ... Controller, 1a ... Wireless communication control unit, 1b ... Sensor measurement unit, 1c ... Power saving management unit DESCRIPTION OF SYMBOLS 1d ... Transmission timing adjustment part, 2a ... Host communication part, 2b ... Wireless communication control part, 2c ... Measurement data management part, TB ... Time slot table, S1-S10 ... Time slot, TS ... Permissible range, 20a ... Carrier detection 20a1 ... first carrier detection unit, 20a2 ... second carrier detection unit, 20b ... time slot allocation unit, 20c ... time slot allocation prohibition unit, 20d ... reception timing check unit, 20e ... notification unit.

Claims (2)

In a wireless communication system comprising a parent device and a battery-powered child device that wirelessly transmits and receives data with the parent device,
The base unit is
When a connection request is received from a slave unit of the wireless communication system to which the mobile station belongs, a unit obtained by time-dividing the period T is defined as a time slot, and any unused time slot in the period T is assigned to the slave unit When,
Means for notifying the slave unit of a time slot assigned to the slave unit as a time from a notification timing of the time slot to a time at a center of the assigned time slot in the next period of the period T ;
Means for checking whether the reception timing of data from the slave unit is within an allowable range centered on the time at the center of the time slot in the time slot allocated to the slave unit that is the transmission source of the data; ,
Means for instructing the transmission slave unit to adjust the data transmission timing so that the data reception timing is at the center of the allowable range when the data reception timing is out of the allowable range ; And
The slave is
A wireless communication system, comprising: means for transmitting data to the parent device at each period T in accordance with a time slot assigned to the child device notified from the parent device. The wireless communication system according to claim 1, wherein
The base unit is
Immediately after receiving the data from the slave unit, the instruction to adjust the transmission timing of the data to the slave unit of the transmission source,
The slave is
A wireless communication system, wherein an instruction to adjust a transmission timing from the parent device is accepted only immediately after the data is transmitted to the parent device.

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