CN107710821B - Wireless communication device, wireless communication method, and computer-readable recording medium - Google Patents

Abstract

The wireless communication master unit (111) sets a 1 st communication timing and a 2 nd communication timing, and receives a wireless frame, wherein the 1 st communication timing is a timing for receiving the wireless frame from wireless communication slave units (131, 132) wirelessly connected to the wireless communication master unit (111), and the 2 nd communication timing is a timing for receiving the wireless frame from a wireless communication slave unit (133) wirelessly connected to the wireless communication master unit (112). When the wireless communication master unit (111) receives the wireless frame from the wireless communication slave unit (133) at the 2 nd communication timing, the wireless communication master unit performs control to switch the connection destination of the wireless connection of the wireless communication slave unit (133) to the wireless communication master unit (111).

Description

Wireless communication device, wireless communication method, and computer-readable recording medium

Technical Field

The present invention relates to handover of wireless communications.

Background

In a communication system of an industrial device, a control amount of the industrial device is repeatedly notified from a device called a master station to a plurality of devices called slave stations, and a state of the industrial device is notified from the plurality of slave stations to the master station.

In this specification, the time from when the master station notifies the plurality of slave stations of the control amount to when the master station receives the status notifications from all of the plurality of slave stations is referred to as a cycle time.

When the cycle time is short, the production efficiency of the industrial equipment and the operation accuracy of the industrial equipment can be improved.

In the past, in a communication system of industrial equipment, the equipment is connected by wire, but in recent years, expectations for wireless communication have been increasing in accordance with the requirements for ease of layout change and wire saving.

In the case of wireless, if user convenience is considered, it is preferable to implement a wireless system of an ISM (Industry-Science-Medical) band, which is a frequency band that does not require a license.

In the ISM band wireless system, it is effective to apply a Local Area Network (LAN) system of IEEE802.11 standard capable of high-speed communication.

However, when a wireless slave unit switches base stations in mobile communication, a packet error occurs when it takes time to switch.

In this regard, patent document 1 discloses a high-speed handoff method for a wireless LAN.

According to the technique of patent document 1, an access point to be connected is selected from access points having a plurality of handover candidates based on a connection history, thereby enabling high-speed handover.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2009 and 49922

Disclosure of Invention

Problems to be solved by the invention

However, when high-speed communication is required as in the communication system of industrial equipment, wireless communication is frequently performed in a wireless communication device that is a handover destination (a switching destination of wireless connection).

Therefore, there is a problem that the handover is not completed before the radio communication is completed in the radio communication apparatus as the handover destination, and it takes a long time to complete the handover.

The present invention has been made to solve the above problems, and a main object of the present invention is to provide a configuration in which a wireless communication terminal can switch a connection destination of a wireless connection at high speed.

Means for solving the problems

A wireless communication device of the present invention includes: a wireless reception unit configured to set a 1 st communication timing and a 2 nd communication timing, and receive a wireless frame, the 1 st communication timing being a timing for receiving a wireless frame from a 1 st wireless communication terminal among a plurality of wireless communication terminals that is wirelessly connected to the wireless communication apparatus, and the 2 nd communication timing being a timing for receiving a wireless frame from a 2 nd wireless communication terminal among the plurality of wireless communication terminals that is wirelessly connected to another wireless communication apparatus other than the wireless communication apparatus; and a switching control unit that controls switching of a connection destination of a radio connection of the 2 nd radio communication terminal when the radio reception unit receives a radio frame from the 2 nd radio communication terminal at the 2 nd communication timing.

Effects of the invention

According to the present invention, since the wireless communication apparatus performs the switching control when the wireless frame is received from the 2 nd wireless communication terminal, it is possible to switch the connection destination of the wireless connection of the 2 nd wireless communication terminal at a high speed.

Drawings

Fig. 1 is a diagram showing a configuration example of a wireless communication system according to embodiment 1.

Fig. 2 is a diagram showing an outline of a functional configuration of a wireless communication master according to embodiment 1.

Fig. 3 is a diagram showing an outline of a functional configuration of the wireless communication slave unit according to embodiment 1.

Fig. 4 is a flowchart illustrating an outline of the operation of the wireless communication master according to embodiment 1.

Fig. 5 is a flowchart illustrating an outline of the operation of the wireless communication slave unit according to embodiment 1.

Fig. 6 is a flowchart illustrating an outline of the operation of the wireless communication slave unit according to embodiment 1.

Fig. 7 is a diagram showing the detailed functional configuration of the wireless communication master according to embodiment 1.

Fig. 8 is a diagram showing the detailed functional configuration of the wireless communication slave unit according to embodiment 1.

Fig. 9 is a diagram showing an example of a master management table of the wireless communication master 111 according to embodiment 1.

Fig. 10 is a diagram showing an example of the master management table of the wireless communication master 112 according to embodiment 1.

Fig. 11 is a diagram showing an example of a slave unit management table of the wireless communication slave unit 131 according to embodiment 1.

Fig. 12 is a diagram showing an example of a slave unit management table of the wireless communication slave unit 132 according to embodiment 1.

Fig. 13 is a diagram showing an example of a slave unit management table of the wireless communication slave unit 133 according to embodiment 1.

Fig. 14 is a diagram showing an example of a communication schedule between the wireless communication master unit 111 and the wireless communication slave units 131 to 133 according to embodiment 1.

Fig. 15 is a diagram showing an example of a communication schedule between the wireless communication master unit 112 and the wireless communication slave units 132 and 133 according to embodiment 1.

Fig. 16 is a diagram showing an example of transmission timing of a response frame from the wireless communication slave unit 133 to the wireless communication master unit 111 according to embodiment 1.

Fig. 17 is a diagram showing an example of transmission timing of a disconnection frame by the slave wireless communication unit 133 according to embodiment 1 to the master wireless communication unit 112.

Fig. 18 is a diagram showing an example of the hardware configuration of the wireless communication master unit and the wireless communication slave unit according to embodiment 1.

Detailed Description

Embodiment mode 1

Description of the systematic Structure

Fig. 1 shows a configuration example of a wireless communication system according to the present embodiment.

As shown in fig. 1, in the radio communication system of the present embodiment, a plurality of radio communication master units 111 and 112 are connected to the master station 101 via L2SW141 and 142 by wire.

The L2SW141 and L2SW142 are layer 2 switches.

The wireless communication slave units 131 and 132 are wirelessly connected to the wireless communication master unit 111, and the wireless communication slave unit 133 is wirelessly connected to the wireless communication master unit 112.

That is, the wireless communication slave units 131 and 132 are connected to the wireless communication master unit 111, and the wireless communication slave unit 133 is connected to the wireless communication master unit 112.

The slave station 121 is connected to the wireless communication slave unit 131 by wire, the slave station 122 is connected to the wireless communication slave unit 132 by wire, and the slave station 123 is connected to the wireless communication slave unit 133 by wire.

Among the slave wireless communication units, the slave wireless communication unit 131 is a fixed station, and the slave wireless communication units 132 and 133 are mobile stations.

As described above, in the radio communication system according to the present embodiment, the radio communication master 111 and the radio communication master 112 are wired to one master station 101.

The wireless communication master 111 and the wireless communication master 112 operate at different radio frequencies.

One or more wireless communication slave units are wirelessly connected to the wireless communication master unit 111 and the wireless communication master unit 112, respectively.

The wireless communication master and the wireless communication slave communicate with each other by CSMA/CA (Carrier Sense Multiple access with Collision Detection).

One slave station is connected to the wireless communication slave unit by wire.

The wireless communication master 111 and the wireless communication master 112 correspond to wireless communication devices, respectively.

The wireless communication slave units 131 to 133 correspond to wireless communication terminals, respectively.

The wireless communication slave units 131 and 132 are wirelessly connected to the wireless communication master unit 111, and the wireless communication master unit 111 corresponds to the 1 st wireless communication terminal.

The wireless communication slave unit 133 is wirelessly connected to the wireless communication master unit 112, and corresponds to the 2 nd wireless communication terminal for the wireless communication master unit 111.

On the other hand, the wireless communication master 112 corresponds to the 1 st wireless communication terminal since the wireless communication slave unit 133 is wirelessly connected to the wireless communication master 112.

The wireless communication slave units 131 and 132 are wirelessly connected to the wireless communication master unit 111, and therefore, the wireless communication master unit 112 corresponds to the 2 nd wireless communication terminal.

The wireless communication master 111 is a wireless communication master to which wireless communication slave units 131 and 132 are connected, and the wireless communication slave units 131 and 132 correspond to existing wireless communication devices.

The wireless communication master 112 is a wireless communication master to which wireless connections of the wireless communication slave units 131 and 132 are switched, and the wireless communication slave units 131 and 132 correspond to switching-destination wireless communication devices.

On the other hand, the wireless communication master 112 is a wireless communication master to which the wireless communication slave unit 133 is connected by wireless connection, and therefore the wireless communication slave unit 133 corresponds to an existing wireless communication device.

The wireless communication master 111 is a wireless communication master to which the wireless communication slave unit 133 is to be switched in wireless connection, and therefore the wireless communication slave unit 133 corresponds to a wireless communication device to which the wireless communication slave unit 133 is to be switched.

The wireless communication slave unit 131 as a fixed station corresponds to a fixed wireless communication terminal, and the wireless communication slave units 132 and 133 as mobile stations correspond to mobile wireless communication terminals.

Summary of the functional structures

Next, an outline of the functional configurations of the wireless communication master 111 and the wireless communication master 112 will be described.

Fig. 2 shows an outline of the functional configurations of the wireless communication master 111 and the wireless communication master 112.

The wireless transmission unit 21 transmits a communication frame by wireless communication.

A communication frame transmitted and received by wireless communication is referred to as a radio frame.

On the other hand, a communication frame transmitted and received by wired communication is referred to as a wired frame.

The radio transmitter 21 transmits a response request frame, which is a radio frame for requesting a response.

Since an example in which the radio transmission unit 21 broadcasts and transmits the response request frame will be described below, the response request frame will also be referred to as a broadcast frame.

The radio transmitter 21 may multicast the response request frame.

The wireless receiving unit 22 receives wireless frames from the wireless communication slave units 131 to 133 in response to the broadcast frame transmitted by the wireless transmitting unit 21.

Next, the wireless frames received by the wireless receiving unit 22 from the wireless communication slave units 131 to 133 as responses to the response request frame are referred to as response frames.

The radio receiving unit 22 sets a 1 st communication timing and a 2 nd communication timing, and receives the response frame, where the 1 st communication timing is a timing for receiving the response frame from the 1 st radio communication terminal, and the 2 nd communication timing is a timing for receiving the response frame from the 2 nd radio communication terminal.

More specifically, the radio receiving unit 22 receives the response frame by repeating a communication cycle including n 1 st communication timings for receiving response frames from n (n ≧ 1) 1 st radio communication terminals and m 2 nd communication timings for receiving response frames from m (m ≧ 1) 2 nd radio communication terminals.

As described above, in the wireless communication master 111, the wireless communication slave units 131 and 132 correspond to the 1 st wireless communication terminal, and the wireless communication slave unit 133 corresponds to the 2 nd wireless communication terminal (n is 2, m is 1).

Therefore, in the wireless receiving unit 22 of the wireless communication master 111, the timing for receiving the response frame from the wireless communication slave units 131 and 132 is the 1 st communication timing, and the timing for receiving the response frame from the wireless communication slave unit 133 is the 2 nd communication timing.

On the other hand, in the wireless communication master 112, the wireless communication slave unit 133 corresponds to the 1 st wireless communication terminal, and the wireless communication slave units 131 and 132 correspond to the 2 nd wireless communication terminal (n is 1 and m is 2).

Therefore, in the wireless receiving unit 22 of the wireless communication master 112, the timing for receiving the response frame from the wireless communication slave unit 133 is the 1 st communication timing, and the timing for receiving the response frame from the wireless communication slave units 131 and 132 is the 2 nd communication timing.

The process performed by the radio receiving unit 22 is also referred to as a radio reception process.

The switching control unit 23 controls switching of the connection destination of the wireless connection of the 2 nd wireless communication terminal when the wireless reception unit 22 receives the response frame from the 2 nd wireless communication terminal at the 2 nd communication timing.

That is, in the wireless communication base unit 111, when the wireless receiving unit 22 receives the response frame from the wireless communication slave unit 133 at the 2 nd communication timing, the switching control unit 23 performs control for switching the connection destination of the wireless connection of the wireless communication slave unit 133 from the wireless communication base unit 112 to the wireless communication base unit 111.

In the wireless communication base unit 112, when the wireless receiving unit 22 receives the response frame from the wireless communication slave unit 131 (or the wireless communication slave unit 132) at the 2 nd communication timing, the switching control unit 23 performs control for switching the connection destination of the wireless connection of the wireless communication slave unit 131 (or the wireless communication slave unit 132) from the wireless communication base unit 111 to the wireless communication base unit 112.

The process performed by the switching control unit 23 is also referred to as a switching control process.

Next, an outline of the functional configuration of the wireless communication slave units 131 to 133 according to the present embodiment will be described.

Fig. 3 shows an outline of the functional configuration of the wireless communication slave units 131 to 133 according to the present embodiment.

The radio receiving unit 31 repeatedly receives a broadcast frame from an existing radio communication apparatus as a connection destination of the current radio connection.

The wireless receiving unit 31 of the wireless communication slave units 131 and 132 repeatedly receives the broadcast frame from the wireless communication master unit 111 which is the active wireless communication device.

The wireless receiving unit 31 of the slave wireless communication unit 133 repeatedly receives the broadcast frame from the master wireless communication unit 112, which is the active wireless communication device.

When it is necessary to switch the connection destination of the wireless connection, the wireless reception unit 31 receives the broadcast frame from the switching-destination wireless communication apparatus that is the switching destination of the wireless connection.

The case where the connection destination of the radio connection needs to be switched is, for example, a case where the reception power of the radio frame from the existing radio communication apparatus is lower than a threshold value.

For example, when it is necessary to switch the connection destination of the wireless connection, the wireless receiving unit 31 of the wireless communication slave units 131 and 132 receives the broadcast frame from the wireless communication master 112, which is a wireless communication device of the switching destination.

When it is necessary to switch the connection destination of the wireless connection, the wireless receiving unit 31 of the wireless communication slave unit 133 receives the broadcast frame from the wireless communication master unit 111, which is a switching destination wireless communication device.

The communication timing detecting unit 32 detects the arrival of the current communication timing, which is a timing for repeatedly transmitting the radio frame to the current wireless communication apparatus.

More specifically, the communication timing detecting unit 32 detects the arrival of the current communication timing with reference to the time when the radio receiving unit 31 receives the radio frame from the current radio communication apparatus.

When it is necessary to switch the connection destination of the wireless connection, the communication timing detecting unit 32 detects the arrival of the communication timing of the switching destination, which is the timing for repeatedly transmitting the wireless frame to the wireless communication device of the switching destination.

More specifically, the communication timing detecting unit 32 detects the arrival of the switching destination communication timing with reference to the time when the wireless receiving unit 31 receives the wireless frame from the switching destination wireless communication apparatus.

The 1 st communication timing and the 2 nd communication timing are classified into communication timings recognized by the wireless communication master units 111 and 112, and the current communication timing and the switching destination communication timing are classified into communication timings recognized by the wireless communication slave units 131 to 133.

For example, the communication timing allocated for the wireless communication slave unit 131 to transmit the response frame to the wireless communication master unit 111 is recognized as the 1 st communication timing in the wireless communication master unit 111 and recognized as the active communication timing in the wireless communication slave unit 131.

On the other hand, the communication timing allocated for the wireless communication slave unit 133 to transmit the response frame to the wireless communication master unit 111 is recognized as the 2 nd communication timing in the wireless communication master unit 111, and is recognized as the switching destination communication timing in the wireless communication slave unit 133.

The process performed by the communication timing detecting unit 32 is also referred to as a communication timing detecting process.

The radio transmission unit 33 transmits a response frame to the incumbent radio communication device at the incumbent communication timing detected by the communication timing detection unit 32.

When it is necessary to switch the connection destination of the wireless connection, the wireless transmission unit 33 transmits a response frame to the switching destination wireless communication apparatus at the switching destination communication timing detected by the communication timing detection unit 32.

After the response frame is transmitted from the wireless transmission unit 33 at the switching destination communication timing, the switching destination wireless communication apparatus starts the switching operation of the connection destination of the wireless connection when receiving the response frame.

The process performed by the radio transmission unit 33 is also referred to as a radio transmission process.

Summary of actions

Next, an outline of the operation of the wireless communication master units 111 and 112 shown in fig. 2 will be described.

Fig. 4 is a flowchart showing an outline of the operation of the wireless communication master 111, 112.

The following description will be given with reference to an operation example of the wireless communication master 111, but the operation of the wireless communication master 112 is also the same as the operation described below.

Next, after transmitting the response request frame (broadcast frame), the wireless communication master 111 waits for the reception of the response frame from the wireless communication slave units 131 and 132 as the 1 st wireless communication terminal, and waits for the reception of the response frame from the wireless communication slave unit 133 as the 2 nd wireless communication terminal.

The steps shown in fig. 4 correspond to examples of the wireless communication method and the wireless communication program.

When the transmission timing of the response request frame arrives, the radio transmission unit 21 broadcasts the transmission response request frame (S401).

Next, the radio receiving unit 22 determines the type of the current communication timing (S402).

If the current communication timing is the 1 st communication timing, that is, the timing at which the response frame is received from the 1 st radio communication terminal, the radio reception unit 22 performs the process of S403.

On the other hand, if the current communication timing is the 2 nd communication timing, that is, the timing at which the response frame is received from the 2 nd wireless communication terminal, the wireless reception unit 22 performs the process of S408.

In S403, the radio receiving unit 22 determines whether or not a response frame is received from the 1 st radio communication terminal.

When the response frame is received (yes in S403), the wireless reception unit 22 transfers the received response frame to an element (not shown in fig. 2) in the wireless communication master 111 that processes the response frame (S404).

On the other hand, when the response frame is not received (no in S403), the wireless transmission unit 21 retransmits the response request frame (S405).

When the response frame is not received even after the 1 st communication timing ends (yes in S406), the radio receiving unit 22 performs an error process (S407).

In the error processing, the wireless reception unit 22 notifies, for example, an element (not shown in fig. 2) that manages the state of the wireless communication slave unit in the wireless communication master unit 111 that the response frame is not received.

In S408, the radio receiving unit 22 determines whether or not a response frame is received from the 2 nd radio communication terminal.

When the response frame is not received (no in S408), the radio receiving unit 22 performs the operation in S410.

On the other hand, when the response frame is received at the 2 nd communication timing (yes in S408), the radio reception unit 22 notifies the switching control unit 23 of the radio communication slave unit that is the sender of the response frame, and the switching control unit 23 performs the switching process (S409).

In the system configuration of fig. 1, when the wireless receiving unit 22 of the wireless communication base unit 111 receives the response frame from the wireless communication slave unit 133 at the 2 nd communication timing, the wireless communication base unit 111 performs a process of switching the connection destination of the wireless connection of the wireless communication slave unit 133 from the wireless communication base unit 112 to the wireless communication base unit 111.

In S410, the radio receiving unit 22 determines whether or not there is an unprocessed communication timing.

If the unprocessed communication timing is present (yes in S410), the radio reception unit 22 performs the operation from S402 onward with respect to the unprocessed communication timing.

When there is no unprocessed communication timing (no in S410), the radio transmission unit 21 transmits a response request frame (S401).

Next, an outline of the operation of the wireless communication slave units 131 to 133 shown in fig. 3 will be described.

Fig. 5 and 6 are flowcharts showing an outline of the operation of the wireless communication slave units 131 to 133.

Fig. 5 is a flowchart showing an operation when each slave wireless communication device transmits a response frame to a master wireless communication device (active wireless communication device) which is a connection destination of the current wireless connection.

Fig. 6 is a flowchart showing an operation when each wireless communication slave unit transmits a response frame to a wireless communication master unit (switching destination wireless communication apparatus) as a switching destination to switch the wireless communication master unit as a connection destination of wireless connection.

The steps shown in fig. 5 and 6 correspond to examples of the wireless communication method and the wireless communication program.

In fig. 5, when the radio receiving unit 31 receives a response request frame transmitted from a wireless communication master as a connection destination of a wireless connection (yes in S501), the communication timing detecting unit 32 determines whether or not a communication timing (current communication timing) has arrived (S502).

The communication timing detecting unit 32 determines that the communication timing has come when a predetermined waiting time has elapsed from the reception timing of the response request frame.

When the communication time arrives (yes in S502), the wireless transmission unit 33 transmits a response frame to the response request frame to the wireless communication master as the connection destination of the wireless connection (S503).

In the wireless communication slave units 131 and 132, the wireless reception unit 31 receives the response request frame broadcast and transmitted from the wireless communication master unit 111 (S501).

In the wireless communication slave unit 131, the communication timing detection unit 32 determines that the communication timing of the wireless communication slave unit 131 has arrived at the point in time when the predetermined waiting time for the wireless communication slave unit 131 has elapsed from the reception timing of the response request frame (yes in S502).

Then, the wireless transmitter 33 transmits the response frame to the wireless communication master 111 (S503).

Similarly, in the wireless communication slave unit 132, the communication timing detection unit 32 determines that the communication timing of the wireless communication slave unit 132 has come when a predetermined waiting time has elapsed for the wireless communication slave unit 132 since the reception timing of the response request frame (yes in S502).

Then, the wireless transmitter 33 transmits the response frame to the wireless communication master 111 (S503).

In the slave wireless communication unit 133, the wireless reception unit 31 receives the response request frame broadcast and transmitted from the master wireless communication unit 112 (S501).

In the wireless communication slave unit 133, the communication timing detection unit 32 determines that the communication timing of the wireless communication slave unit 133 has arrived at the point in time when the predetermined waiting time for the wireless communication slave unit 133 has elapsed from the reception timing of the response request frame (yes in S502).

Then, the wireless transmitter 33 transmits the response frame to the wireless communication master 112 (S503).

In fig. 6, when it is necessary to switch the wireless communication master (yes in S601), the wireless reception unit 31 determines the wireless communication master to which the wireless connection is to be switched (S602).

Then, when the radio receiver 31 receives the response request frame from the radio communication master as the switching destination (yes in S603), the communication timing detector 32 determines whether or not the communication timing (switching destination communication timing) has arrived (S604).

The communication timing detecting unit 32 determines that the communication timing has come when a predetermined waiting time has elapsed from the reception timing of the response request frame.

When the communication time arrives (yes in S604), the radio transmission unit 33 transmits a response frame to the response request frame to the switching-destination radio communication master (S605).

When the wireless communication slave units 131 and 132 need to switch the wireless communication master unit (yes in S601), the wireless reception unit 31 determines the switching destination of the wireless connection as the wireless communication master unit 112, and receives the response request frame broadcast and transmitted from the wireless communication master unit 112 as the switching destination (S602 and S603).

In the wireless communication slave unit 131, the communication timing detection unit 32 determines that the communication timing of the wireless communication slave unit 131 has arrived at the point in time when the predetermined waiting time for the wireless communication slave unit 131 has elapsed from the reception timing of the response request frame (yes in S604).

Then, the wireless transmitter 33 transmits the response frame to the wireless communication master 112 (S605).

Similarly, in the wireless communication slave unit 132, the communication timing detecting unit 32 determines that the communication timing of the wireless communication slave unit 132 has come when a predetermined waiting time has elapsed for the wireless communication slave unit 132 since the reception timing of the response request frame (yes in S604).

Then, the wireless transmitter 33 transmits the response frame to the wireless communication master 112 (S605).

When the wireless communication master unit needs to be switched in the wireless communication slave unit 133 (yes in S601), the wireless reception unit 31 determines the switching destination of the wireless connection as the wireless communication master unit 111, and receives the response request frame broadcast and transmitted from the wireless communication master unit 111 as the switching destination (S602, S603).

In the wireless communication slave unit 133, the communication timing detection unit 32 determines that the communication timing of the wireless communication slave unit 133 has arrived at the point in time when the predetermined waiting time for the wireless communication slave unit 133 has elapsed from the reception timing of the response request frame (yes in S604).

Then, the wireless transmitter 33 transmits the response frame to the wireless communication master 111 (S605).

Detailed description of the functional structures

Next, the functional configuration of the wireless communication master units 111 and 112 will be described in detail.

Fig. 7 shows the details of the functional configuration of the wireless communication master 111, 112.

In addition, although the functional configuration of the wireless communication base unit 111 is described below, the following description is also applicable to the wireless communication base unit 112.

In fig. 7, the master management table 201 manages identification information of a mobile station of a wireless communication slave unit in the wireless communication system, identification information of a fixed station connected to the wireless communication master unit 111, communication timing, and a connection state.

The wired frame receiving unit 202 receives a wired frame.

The wired frame analyzing unit 203 analyzes the wired frame received by the wired frame receiving unit 202, and determines whether the wired frame received by the wired frame receiving unit 202 is a wired frame from the master station 101 or a wired frame from another wireless communication master 112.

In the case of the wired frame from the master station 101, the wired frame analyzing unit 203 notifies the wireless frame generating unit 204 of data included in the wired frame.

In the case of a wired frame from another wireless communication master 112, the wired frame analysis unit 203 notifies the connection management unit 210 of data included in the wired frame.

The wireless frame generation unit 204 generates a wireless frame for notifying the wireless communication slave unit of the data notified from the wired frame analysis unit 203.

The radio frame generator 204 generates a radio frame to which the retransmission instruction unit 212 instructs retransmission.

The radio frame transmitting unit 205 wirelessly transmits the radio frame generated by the radio frame generating unit 204.

The wireless frame transmitting unit 205 notifies the communication timing control unit 211 of the timing at which the wireless frame is transmitted.

The wireless frame receiving unit 206 receives a wireless frame from the wireless communication slave unit.

The wireless frame analyzing unit 207 analyzes the wireless frame received by the wireless frame receiving unit 206, and determines from which wireless communication slave unit the wireless frame received by the wireless frame receiving unit 206 is.

When the radio frame receiving unit 206 does not receive the radio frame, the radio frame analyzing unit 207 notifies the communication timing control unit 211 that the radio frame is not received.

When receiving a wireless frame from a wireless communication slave unit wirelessly connected to the wireless communication master unit 111, the wireless frame analyzing unit 207 notifies the wired frame generating unit 208 of data included in the wireless frame.

When receiving a wireless frame from a wireless communication slave unit wirelessly connected to the wireless communication master unit 111, the wireless frame analysis unit 207 notifies the connection management unit 210 of the wireless communication slave unit as a wireless frame transmission source.

The wired frame generating unit 208 generates a wired frame for notifying the master station 101 of the data notified from the wireless frame analyzing unit 207.

The wired frame generating unit 208 generates a wired frame for notifying the other wireless communication base unit 112 of the change in the connection state of the wireless communication slave unit, in accordance with an instruction from the connection managing unit 210.

The wired frame transmitting unit 209 transmits the wired frame generated by the wired frame generating unit 208 in a wired manner.

The connection management unit 210 updates the connection state managed by the master management table 201 based on the data notified from the wired frame analysis unit 203 and the data notified from the wireless frame analysis unit 207.

Then, the connection management unit 210 notifies the communication timing control unit 211 of the updated connection state.

The communication timing control unit 211 generates a communication timing for each wireless communication slave unit based on the transmission timing notified from the wireless frame transmission unit 205.

When the wireless frame is not received from the wireless communication slave unit 131 or the wireless communication slave unit 132, the communication timing control unit 211 instructs the retransmission instruction unit 212 to retransmit the wireless frame.

When a retransmission instruction is given from the communication timing control unit 211, the retransmission instruction unit 212 instructs the radio frame generation unit 204 to retransmit the radio frame.

In the configuration of fig. 7, the radio frame generation unit 204 and the radio frame transmission unit 205 correspond to the radio transmission unit 21 shown in fig. 2.

That is, the radio frame generator 204 generates a response request frame, and the radio frame transmitter 205 transmits the response request frame.

The radio frame receiving unit 206, the radio frame analyzing unit 207, and the communication timing control unit 211 correspond to the radio receiving unit 22 shown in fig. 2.

That is, the wireless frame receiving unit 206 receives the response frame, and the wireless frame analyzing unit 207 determines from which wireless communication slave unit the response frame received by the wireless frame receiving unit 206 was transmitted.

Then, the communication timing control section 211 determines whether the current communication timing is the 1 st communication timing or the 2 nd communication timing.

The connection management unit 210 corresponds to the switching control unit 23 shown in fig. 2.

That is, the connection management unit 210 updates the connection state managed by the master management table 201, thereby switching the connection destination of the wireless connection of the 2 nd wireless communication slave unit.

Next, the functional configuration of the wireless communication slave units 131 to 133 will be described in detail.

Fig. 8 shows the functional configuration of the wireless communication slave units 131 to 133 in detail.

In fig. 8, a slave unit management table 301 manages identification information, connection state, and communication timing of a wireless communication master unit of a connection candidate in a wireless communication system.

The wired frame receiving unit 302 receives a wired frame from a slave station.

The wireless frame generation unit 303 generates a wireless frame for notifying data included in the wired frame received by the wired frame reception unit 302.

When the response control unit 308 instructs transmission of a response, the wireless frame generation unit 303 generates a wireless frame for notifying of the response.

The radio frame transmitting unit 304 wirelessly transmits the radio frame generated by the radio frame generating unit 303.

The radio frame transmitting unit 304 switches the frequency of the transmission radio frame when instructed to switch the frequency by the radio frequency switching unit 309.

The wireless frame receiving unit 305 receives a wireless frame from a wireless communication master.

The radio frame receiving unit 305 transfers the received radio frame to the radio frame analyzing unit 306.

The radio frame reception unit 305 then notifies the response control unit 308 of the reception power of the radio frame.

The radio frame receiving unit 305 switches the frequency of the received radio frame when instructed to switch the frequency by the radio frequency switching unit 309.

The radio frame analyzing unit 306 analyzes the radio frame transferred from the radio frame receiving unit 305, and determines whether to notify the slave station of data included in the radio frame.

When the slave station is notified of data included in the wireless frame, the slave station notifies the wired frame transmission unit 307 of the data.

When the radio frame transferred from the radio frame receiving unit 305 is analyzed and, as a result, it is determined that the radio frame is a response request frame from the wireless communication master, the radio frame analyzing unit 306 notifies the response control unit 308 that the response request frame is received.

The wired frame transmitting unit 307 transmits a wired frame for notifying the slave station of the data notified from the wireless frame analyzing unit 306.

When the reception of the response request frame from the wireless communication master is notified by the wireless frame analysis unit 306, the response control unit 308 detects the arrival of the communication timing assigned to the wireless communication slave unit.

Then, when detecting the arrival of the communication timing, the response control unit 308 instructs the wireless frame generation unit 303 to transmit a response.

The response control unit 308 determines whether or not the frequency needs to be switched based on the received power reported from the radio frame receiving unit 305, and instructs the radio frequency switching unit 309 to switch the frequency when the frequency needs to be switched.

The radio frequency switching unit 309 instructs the radio frame transmitting unit 304 to switch the transmission frequency of the radio frame and instructs the radio frame receiving unit 305 to switch the reception frequency of the radio frame, in response to the instruction of switching the frequency from the response control unit 308.

In the configuration of fig. 8, the radio frame receiving unit 305 and the radio frequency switching unit 309 correspond to the radio receiving unit 31 shown in fig. 3.

That is, the wireless frame receiving unit 305 receives a wireless frame from a wireless communication master that is a connection destination of the current wireless connection.

When the wireless communication master needs to be switched, the wireless frequency switching unit 309 controls the switching of the reception frequency to search for the wireless communication master to which the wireless connection is to be switched, and the wireless frame receiving unit 305 receives the wireless frame from the wireless communication master to which the wireless connection is to be switched.

The response control unit 308 corresponds to the communication timing detection unit 32 shown in fig. 3.

That is, the response control unit 308 detects the arrival of a communication timing to transmit the wireless frame to the wireless communication master that is the connection destination of the current wireless connection.

When the wireless communication master needs to be switched, the response control unit 308 detects the arrival of communication timing for transmitting a wireless frame to the wireless communication master as a switching destination of wireless connection.

The radio frame transmitting unit 304 and the radio frequency switching unit 309 correspond to the radio transmitting unit 33 shown in fig. 3.

That is, the radio frequency switching unit 309 matches the transmission frequency with the frequency of the wireless communication master as the switching destination of the wireless connection so that the radio frame transmitting unit 304 can transmit the radio frame to the wireless communication master as the switching destination of the wireless connection.

Then, the wireless frame transmitting unit 304 transmits the wireless frame to the wireless communication master as the switching destination of the wireless connection at the communication timing with the wireless communication master as the switching destination of the wireless connection detected by the response control unit 308.

Next, the master management table 201 shown in fig. 7 will be described.

The master management table 201 includes the wireless communication slave unit type, wireless communication slave unit identification information, communication timing, and connection state.

The column of the wireless communication slave unit type shows the type of whether the wireless communication slave unit is a mobile station or a fixed station.

The column of the wireless communication slave unit identification information shows identification information of the wireless communication slave unit.

The column of the connection state shows whether or not the wireless communication slave unit is wirelessly connected.

As described above, the column of the communication timing shows the timing at which the slave wireless communication unit transmits the response frame to the response request frame transmitted by the master wireless communication unit.

The order of transmission of the response frames is specified for each wireless communication slave unit, and if the response frames transmitted by all the wireless communication slave units are of a fixed length, the communication timing of each wireless communication slave unit can be estimated from the order of transmission of the response frames.

In addition, when the response frame length differs depending on the wireless communication slave unit, the wireless communication timing of each wireless communication slave unit can be estimated from the time required for transmission of each response frame.

Next, assuming that the response frames transmitted by all the wireless communication slave units are of a fixed length, the communication timing of each wireless communication slave unit is estimated based on the transmission order of the response frames.

The transmission sequence of the response frame of the slave wireless communication unit is described in the column of the communication timing of the master management table 201.

Fig. 9 shows an example of the master management table 201 of the wireless communication master 111.

Since the wireless communication slave units 131 and 132 are currently connected to the wireless communication master unit 111, the wireless communication slave units 131 and 132 are connected to each other, and the wireless communication slave unit 133 is not connected to each other.

Fig. 10 shows an example of the master management table 201 of the wireless communication master 112.

Currently, since the wireless communication slave unit 133 is connected to the wireless communication master unit 112, the connection state with the wireless communication slave unit 133 is connected, and the connection state with the wireless communication slave unit 132 is not connected.

Since the wireless communication slave unit 131 is a fixed station connected to the wireless communication master unit 111, the master unit management table of the wireless communication master unit 112 does not include information of the wireless communication slave unit 131.

Fig. 11 shows an example of the slave unit management table 301 of the wireless communication slave unit 131.

Fig. 12 shows an example of the slave unit management table 301 of the wireless communication slave unit 132.

Fig. 13 shows an example of the slave unit management table 301 of the wireless communication slave unit 133.

Since the wireless communication slave unit 131 is a fixed station, only the wireless communication master unit 111 is a connection candidate in fig. 11.

On the other hand, since the wireless communication slave units 132 and 133 are mobile stations, the connection candidates are the wireless communication master unit 111 and the wireless communication master unit 112 in fig. 12 and 13.

Since the wireless communication slave unit 132 is connected to the wireless communication master unit 111, the connection state with the wireless communication master unit 111 is connected, and the connection state with the wireless communication master unit 112 is not connected.

Since the wireless communication slave unit 133 is connected to the wireless communication master unit 112, the connection state with the wireless communication master unit 111 is disconnected, and the connection state with the wireless communication master unit 112 is connected.

Detailed description of the actions

Next, the operation of the wireless communication master unit shown in fig. 7 and the wireless communication slave unit shown in fig. 8 will be described in detail.

First, operations of the wireless communication master 111 and the wireless communication slave units 131 to 133 when the wireless communication master 111 transmits a broadcast frame (response request frame) will be described based on the example of the communication schedule shown in fig. 14.

In fig. 14, the wireless communication master unit 111 transmits a broadcast frame (response request frame) in a time slot 901, the wireless communication slave unit 132 transmits a response frame to the wireless communication master unit 111 in a time slot 902, and the wireless communication slave unit 131 transmits a response frame to the wireless communication master unit 111 in a time slot 904.

The time slot 903 is a communication timing for the wireless communication slave unit 133 to transmit the response frame to the wireless communication master unit 111, but since the wireless communication slave unit 133 is wirelessly connected to the wireless communication master unit 112, the wireless communication slave unit 133 does not transmit the response frame to the wireless communication master unit 111 in the time slot 903 in normal times (when it is not necessary to switch the connection destination of the wireless connection).

In fig. 14, a time slot 902 is a communication timing for the wireless communication base unit 111 to receive a response frame from the wireless communication slave unit 132 wirelessly connected to the wireless communication base unit 111, and corresponds to the 1 st communication timing.

The time slot 902 is a communication timing for the slave radio communication unit 132 to transmit a response frame to the master radio communication unit 111 to which the current radio connection is to be connected, and corresponds to the current communication timing.

The time slot 903 is a communication timing for the wireless communication master 111 to receive a response frame from the wireless communication slave unit 133 wirelessly connected to the wireless communication master 112, and corresponds to the 2 nd communication timing.

The time slot 903 is a communication timing for the wireless communication slave unit 133 to transmit a response frame to the wireless communication master unit 111 to which the wireless connection is switched, and corresponds to a switching communication timing.

The time slot 904 is a communication timing at which the wireless communication master 111 receives a response frame from the wireless communication slave unit 131 wirelessly connected to the wireless communication master 111, and corresponds to the 1 st communication timing.

The time slot 904 is a communication timing for transmitting the response frame to the wireless communication master 111 to which the wireless communication slave unit 131 is connected in the current wireless connection, and corresponds to the current communication timing.

First, a procedure in which the wireless communication master 111 transmits a broadcast frame (response request frame) in the time slot 901 will be described.

In the wireless communication master 111, the wired frame receiving unit 202 receives a broadcast frame transmitted from the master station 101 by wired communication.

Next, the wired frame analyzing unit 203 analyzes the broadcast frame, and generates a wireless frame (response request frame) by the wireless frame generating unit 204.

Then, the radio frame transmitting unit 205 performs radio transmission of the radio frame (response request frame) generated by the radio frame generating unit 204.

At this time, the wireless frame transmitting unit 205 notifies the communication timing control unit 211 of the transmission timing of the wireless frame (response request frame).

The communication timing control unit 211 generates a communication timing for receiving a response frame for each wireless communication slave unit, based on the transmission timing of the wireless frame (response request frame) notified from the wireless frame transmitting unit 205 and the transmission sequence described in the column of the communication timing of the master unit management table 201 (fig. 9).

Then, the communication timing control unit 211 waits for the reception of the response frame from the wireless communication slave unit.

Next, a procedure in which the wireless communication slave unit 132 connected to the wireless communication master unit 111 transmits a response frame in the time slot 902 will be described.

In the wireless communication slave unit 132, the wireless frame receiving unit 305 receives the wireless frame (response request frame) from the wireless communication master unit 111 in the time slot 901.

Then, the wireless frame analyzing unit 306 analyzes the wireless frame received by the wireless frame receiving unit 305, and transfers data included in the wireless frame to the wired frame transmitting unit 307.

Then, the wired frame transmitting unit 307 transmits a wired frame including data included in the wireless frame to the slave station 122.

The wireless frame analysis unit 306 notifies the response control unit 308 that the wireless frame has been received.

The response control unit 308 refers to the slave unit management table 301 (fig. 10), and instructs the wireless frame generation unit 303 to transmit a response frame when the communication timing described in the slave unit management table 301 arrives.

The response control unit 308 detects the arrival of the communication timing of the wireless communication slave unit 132 in the transmission order described in the column of the communication timing of the slave unit management table 301 with reference to the reception timing of the wireless frame (response request frame) from the wireless communication master unit 111.

The radio frame generator 303 generates a response frame, and the radio frame transmitter 304 wirelessly transmits the response frame to the wireless communication master 111.

As a result, the wireless communication slave unit 132 transmits a response frame to the wireless communication master unit 111 in time slot 902 of fig. 14.

When the radio frame is received, the radio frame reception unit 305 notifies the response control unit 308 of the reception power of the radio frame, but here, the response control unit 308 determines that the reception power of the radio frame is sufficiently large and determines that it is not necessary to switch the radio connection destination.

The wireless communication slave unit 133 is not connected to the wireless communication master unit 111, and the reception frequency of the wireless frame receiving unit 305 of the wireless communication slave unit 133 does not match the frequency of the wireless communication master unit 111.

Therefore, the wireless communication slave unit 133 does not receive the wireless frame (response request frame) from the wireless communication master unit 111 in the time slot 901.

Therefore, the wireless communication slave unit 133 does not transmit the response frame to the wireless communication master unit 111 in the time slot 903.

The wireless communication slave unit 131 operates in the same manner as the wireless communication slave unit 132, and the wireless communication slave unit 131 transmits a response frame to the wireless communication master unit 111 in time slot 904.

Next, an operation when the wireless communication master 111 receives a response frame from the wireless communication slave unit will be described.

In the wireless communication master 111, the wireless frame receiving unit 206 receives a response frame from the wireless communication slave unit 132 in the time slot 902.

The wireless frame analyzing unit 207 analyzes the response frame received by the wireless frame receiving unit 206, and recognizes that the response frame is received from the wireless communication slave unit 132.

The wireless frame analysis unit 207 notifies the communication timing control unit 211 of the reception of the response frame from the wireless communication slave unit 132.

The communication timing control unit 211 confirms that the response frame from the wireless communication slave unit 132 has been received in the time slot 902, and waits for the wireless communication slave unit 133 to receive the response frame.

When the wireless frame receiving unit 206 cannot receive the response frame from the wireless communication slave unit 132 in the time slot 902, the communication timing control unit 211 notifies the retransmission instructing unit 212 that the response frame from the wireless communication slave unit 132 cannot be received.

Then, the retransmission instructing unit 212 notifies the wireless frame generating unit 204 of retransmission of the response request frame to the wireless communication slave unit 132.

The wireless frame generation unit 204 outputs the response request frame to the wireless frame transmission unit 205, and the wireless frame transmission unit 205 retransmits the response request frame to the wireless communication slave unit 132 by unicast.

As described above, since the slave wireless communication unit 133 is connected to the master wireless communication unit 112 at present, the response frame is not transmitted in the time slot 903.

Therefore, the wireless communication master 111 does not receive the response frame in the time slot 903.

The communication timing control unit 211 does not receive the response frame in the time slot 903, and thus refers to the master management table 201.

The communication timing control unit 211 checks that the wireless communication slave unit 133 to which the time slot 903 is allocated is not connected to the wireless communication master unit 111 by referring to the master unit management table 201.

Then, the communication timing control unit 211 determines not to retransmit the response request frame to the wireless communication slave unit 133, and waits for reception of a response frame of the next wireless communication slave unit 131.

In the wireless communication master 111, the wireless frame receiving unit 206 receives a response frame from the wireless communication slave unit 131 in a time slot 904.

The operation of the wireless communication master 111 in the time slot 904 is the same as the operation of the wireless communication master 111 in the time slot 902, and therefore, the description thereof is omitted.

Next, operations of the wireless communication master 112 and the wireless communication slave units 131 to 133 when the wireless communication master 112 transmits a broadcast frame (response request frame) will be described based on an example of a communication schedule shown in fig. 15.

In fig. 15, the wireless communication master 112 transmits a broadcast frame (response request frame) in a time slot 1001, and the wireless communication slave unit 133 transmits a response frame to the wireless communication master 112 in a time slot 1003.

The time slot 1002 is a communication timing for the wireless communication slave unit 132 to transmit the response frame to the wireless communication master unit 112, but since the wireless communication slave unit 132 is wirelessly connected to the wireless communication master unit 111, the wireless communication slave unit 132 does not transmit the response frame to the wireless communication master unit 112 in the time slot 1002 in a normal case (when it is not necessary to switch the connection destination of the wireless connection).

The wireless communication slave unit 131 is a fixed station wirelessly connected to the wireless communication master unit 111, and is not wirelessly connected to the wireless communication master unit 112, and therefore, the communication timing for the wireless communication slave unit 131 is not set in the wireless communication master unit 112.

Therefore, the wireless communication master 112 does not cause a delay due to waiting for a response frame from the wireless communication slave unit 131.

In fig. 15, a time slot 1002 is a communication timing at which the wireless communication base unit 112 receives a response frame from the wireless communication slave unit 132 wirelessly connected to the wireless communication base unit 111, and corresponds to the 2 nd communication timing.

The time slot 1002 is a communication timing for the wireless communication slave unit 132 to transmit a response frame to the wireless communication master unit 112 as a switching destination of the wireless connection, and corresponds to a switching communication timing.

The time slot 1003 is a communication timing for the wireless communication base unit 112 to receive a response frame from the wireless communication slave unit 133 wirelessly connected to the wireless communication base unit 112, and corresponds to the 1 st communication timing.

The time slot 1003 is a communication timing for the slave wireless communication unit 133 to transmit the response frame to the master wireless communication unit 112, which is the connection destination of the current wireless connection, and corresponds to the current communication timing.

The operation of the wireless communication master 112 when receiving the response frame from the wireless communication slave unit 133 in the time slot 1003 is the same as the operation of the wireless communication master 111 when receiving the response frame from the wireless communication slave unit 132 in the time slot 902 of fig. 14.

The operation of the wireless communication master 112 when the response frame from the wireless communication slave unit 133 is not received in the time slot 1003 is the same as the operation of the wireless communication master 111 when the response frame from the wireless communication slave unit 132 is not received in the time slot 902 of fig. 14.

Next, an operation of the wireless communication slave unit 133 being handed over from the wireless communication master unit 111 to the wireless communication master unit 112 will be described.

In the wireless communication slave unit 133, the response control unit 308 is notified of the received power of the response request frame from the wireless communication master unit 112 by the wireless frame receiving unit 305, and then compares the notified received power with the threshold.

Then, when the reception power of the response request frame from the master radio communication unit 112 is lower than the threshold value and the radio frame transmitting unit 304 and the radio frame receiving unit 305 do not communicate with each other, the response control unit 308 instructs the radio frequency switching unit 309 to search for another master radio communication unit.

The radio frequency switching unit 309 sequentially switches the reception frequency of the radio frame receiving unit 305.

Then, when the wireless frame receiving unit 305 receives the response request frame from the wireless communication master 111 with the reception power equal to or higher than the threshold, the wireless frame transmitting unit 304 transmits the response frame to the wireless communication master 111 at the communication timing for the wireless communication slave unit 133 to transmit the response frame to the wireless communication master 111.

Fig. 16 shows a communication schedule in a case where the wireless communication slave unit 133 transmits a response frame to the wireless communication master unit 111.

In fig. 16, a slot 1101 is a communication timing for transmitting a response request frame by the master radio communication unit 111.

The slot 1102 is a communication timing for the wireless communication slave unit 132 to transmit a response frame to the wireless communication master unit 111.

The time slot 1103 is a communication timing for the wireless communication slave unit 133 to transmit the response frame to the wireless communication master unit 111.

The time slot 1104 is a communication timing for the wireless communication slave unit 131 to transmit a response frame to the wireless communication master unit 111.

The wireless communication slave unit 133 transmits a response frame to the wireless communication master unit 111 at time slot 1103, thereby switching the connection destination of the wireless connection from the wireless communication master unit 112 to the wireless communication master unit 111.

At this time, the response control unit 308 of the wireless communication slave unit 133 changes the connection state of the slave unit management table 301 to the connection state of the wireless communication master unit 111 and the disconnection state of the wireless communication master unit 112.

In the wireless communication master 111, when receiving the response frame from the wireless communication slave unit 133 at time slot 1103, the wireless frame analysis unit 306 notifies the connection management unit 210 of the wireless communication slave unit 133 as the sender of the response frame.

The connection management unit 210 changes the connection state of the wireless communication slave unit 133 in the master unit management table 201 to connection.

The connection management unit 210 instructs the wired frame generation unit 208 to generate a connection notification frame for notifying the wireless communication master 112 that the wireless communication slave unit 133 is connected to the wireless communication master 111.

The wired frame generation unit 208 generates a connection notification frame.

Then, the wired frame transmitting unit 209 broadcasts and transmits a connection notification frame.

Further, the connection management unit 210 broadcasts and transmits the virtual frame of the wireless communication slave unit 133 via the wired frame generation unit 208 and the wired frame transmission unit 209 in order for the L2SW141, 142 to learn the path of the unicast frame of the wireless communication slave unit 133.

The connection management unit 210 may transmit a wired frame in which the connection notification frame and the virtual frame are integrated.

In the wireless communication master 112, the wired frame receiving unit 202 receives the connection notification frame transmitted from the wireless communication master 111.

The wired frame analyzing unit 203 analyzes the connection notification frame and determines that the connection notification frame is a wired frame from the wireless communication master 111.

Then, the wired frame analysis unit 203 notifies the connection management unit 210 of the data included in the connection notification frame (data to the effect that the wireless communication slave unit 133 has connected to the wireless communication master unit 111).

The connection management unit 210 changes the connection state of the wireless communication slave unit 133 in the master unit management table 201 to unconnected state.

The connection management unit 210 notifies the communication timing control unit 211 that the wireless communication slave unit 133 is not connected to the wireless communication master unit 112.

Since the communication timing control unit 211 is notified that the wireless communication slave unit 133 is not connected, the retransmission instructing unit 212 does not instruct the wireless communication slave unit 133 to retransmit the response request frame even if the response frame is not received from the wireless communication slave unit 133.

Description of effects of embodiments

As described above, in the present embodiment, the wireless communication master unit has a communication timing for receiving a response frame from a wireless communication slave unit connected to the wireless communication master unit, and a communication timing for receiving a response frame from a wireless communication slave unit connected to another wireless communication master unit.

Therefore, according to the present embodiment, the wireless communication master can perform switching control when receiving a response frame from a wireless communication slave unit connected to another wireless communication master unit, and can complete handover at high speed.

Attached with

The above describes the procedure in which the wireless communication slave unit 133 transmits the response frame to the wireless communication master unit 111 to which the wireless connection is switched.

Alternatively, the slave wireless communication unit 133 may transmit the disconnection frame to the master wireless communication unit 112 and then transmit the response frame to the master wireless communication unit 111.

When the reception power of the response request frame received from the wireless communication master 112 is lower than the threshold, the wireless frequency switching unit 309 of the wireless communication slave unit 133 sequentially switches the reception frequency of the wireless frame receiving unit 305, and searches for another wireless communication master.

When the received power from the wireless communication master 111 is stronger than the received power from the wireless communication master 112, the response control unit 308 of the wireless communication slave unit 133 causes the wireless frame generation unit 303 to generate a disconnection frame and causes the wireless frame transmission unit 304 to transmit the disconnection frame at a communication timing for transmitting a response frame to the wireless communication master 112.

Fig. 17 shows a communication schedule in a case where the wireless communication slave unit 133 transmits the disconnection frame to the wireless communication master unit 112.

In fig. 17, a time slot 1201 is a communication timing for transmitting a response request frame by the master radio communication unit 112.

The time slot 1202 is a communication timing for the wireless communication slave unit 132 to transmit a response frame to the wireless communication master unit 112.

The time slot 1203 is a communication timing for the wireless communication slave unit 133 to transmit a response frame to the wireless communication master unit 112.

The wireless communication slave unit 133 transmits a disconnection frame to the wireless communication master unit 112 in a time slot 1203.

The disconnection frame is a wireless frame requesting the master radio communication device 112 to switch the wireless connection to the master radio communication device 111.

After the transmission of the disconnection frame, the radio frequency switching unit 309 of the wireless communication slave unit 133 changes the transmission frequency of the wireless frame transmitting unit 304 and the reception frequency of the wireless frame receiving unit 305 to the frequency used by the wireless communication master unit 111.

Then, the response control unit 308 waits for reception of the wireless frame from the wireless communication master 111.

In the wireless communication master 112 that has received the disconnection frame from the wireless communication slave unit 133, the connection management unit 210 changes the connection state of the wireless communication slave unit 133 in the master management table 201 to unconnected.

Further, the connection management unit 210 transmits a handover notification frame for notifying the wireless communication master unit 111 of handover of the wireless communication slave unit 133 via the wired frame generation unit 208 and the wired frame transmission unit 209.

Upon receiving the handover notification frame from the wireless communication master 112, the connection management unit 210 causes the wireless communication slave unit 133 in the master management table 201 to establish a connection state in the wireless communication master 111.

The connection management unit 210 notifies the communication timing control unit 211 that the response request frame is retransmitted to the wireless communication slave unit 133 when the response frame is not received from the wireless communication slave unit 133.

The connection management unit 210 broadcasts and transmits the virtual frame of the wireless communication slave unit 133 via the wired frame generation unit 208 and the wired frame transmission unit 209 in order for the L2SW141, 142 to learn the path of the unicast frame of the wireless communication slave unit 133.

Further, the connection management unit 210 instructs the wireless frame generation unit 204 to generate a virtual frame addressed to the wireless communication slave unit 133 to confirm whether or not the wireless communication slave unit 133 is connected to the wireless communication master unit 111.

The wireless frame generation unit 204 generates a virtual frame in response to an instruction from the connection management unit 210, and the wireless frame transmission unit 205 unicast-transmits the virtual frame to the wireless communication slave unit 133.

As described above, the slave wireless communication unit notifies the currently connected master wireless communication unit of disconnection of the wireless connection and the master wireless communication unit to which the wireless connection is to be switched.

In this case, since the retransmission control of the slave wireless communication unit can be performed by the master wireless communication unit as the handover destination, the frame arrival rate of the master wireless communication unit as the handover destination is improved.

Description of hardware structural examples

Finally, an example of the hardware configuration of the wireless communication master units 111 and 112 and the wireless communication slave units 131 to 133 will be described with reference to fig. 18.

The wireless communication master units 111 and 112 and the wireless communication slave units 131 to 133 are computers.

The wireless communication master units 111 and 112 and the wireless communication slave units 131 to 133 include hardware such as a processor 1901, an auxiliary storage device 1902, a memory 1903, a communication device 1904, an input interface 1905, and a display interface 1906.

The processor 1901 is connected to other hardware via signal lines 1910 and controls these other hardware.

The input interface 1905 is connected to an input device 1907.

The display interface 1906 interfaces with a display 1908.

The processor 1901 is an Integrated Circuit (IC) that performs processing.

The Processor 1901 is, for example, a CPU (Central Processing Unit), a DSP (digital signal Processor), or a GPU (Graphics Processing Unit).

The auxiliary storage device 1902 is, for example, a ROM (Read Only Memory), a flash Memory, an HDD (hard disk Drive).

The Memory 1903 is, for example, a RAM (Random Access Memory).

The communication device 1904 includes a receiver 19041 for receiving data and a transmitter 19042 for transmitting data.

The communication device 1904 is, for example, a communication chip or an NIC (Network Interface Card).

The input interface 1905 is a port for connecting a cable 1911 of the input device 1907.

The display interface 1906 is a port for a cable 1912 connecting the display 1908.

The input device 1907 and the display 1908 are, for example, a touch panel.

The auxiliary storage device 1902 stores a program for realizing the functions of the units shown in fig. 2, 3, 7, and 8.

The program is loaded into the memory 1903, read into the processor 1901, and executed by the processor 1901.

Further, the auxiliary storage device 1902 stores an OS (Operating System).

Then, at least a part of the OS is loaded into the memory 1903, and the processor 1901 executes the OS and executes a program that realizes the function of the "-" section ".

Although one processor 1901 is illustrated in fig. 18, the wireless communication master units 111 and 112 and the wireless communication slave units 131 to 133 may have a plurality of processors 1901.

The processors 1901 may cooperate with each other to execute a program that realizes the functions of the units.

Information, data, signal values, and variable values representing the processing results of the units are stored in a register or a cache in the memory 1903, the auxiliary storage device 1902, or the processor 1901.

Further, a program for realizing the functions of the units is stored in a storage medium such as a magnetic disk, a flexible disk, an optical disk, a compact disk, a blu-ray (registered trademark) disk, or a DVD.

The "section" may also be provided by "processing circuitry".

Further, the "units" may be rewritten into "circuits" or "processes" or "steps" or "processes".

The term "Circuit" and "processing circuitry" are used to encompass not only the processor 1901 but also other types of processing circuits such as a logic IC (logic Array) or an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

Description of the reference symbols

21: a wireless transmission unit; 22: a wireless receiving unit; 23: a switching control unit; 31: a wireless receiving unit; 32: a communication timing detecting section; 33: a wireless transmission unit; 101: a master station; 111: a wireless communication master; 112: a wireless communication master; 121: a slave station; 122: a slave station; 123: a slave station; 131: a wireless communication sub machine; 132: a wireless communication sub machine; 133: a wireless communication sub machine; 141: l2 SW; 142: l2 SW; 201: a master management table; 202: a wired frame receiving unit; 203: a wired frame analyzing section; 204: a wireless frame generation unit; 205: a wireless frame transmitting section; 206: a wireless frame receiving section; 207: a wireless frame analysis unit; 208: a wired frame generating unit; 209: a wired frame transmitting unit; 210: a connection management unit; 211: a communication timing control unit; 212: a retransmission instruction unit; 301: a sub machine management table; 302: a wired frame receiving unit; 303: a wireless frame generation unit; 304: a wireless frame transmitting section; 305: a wireless frame receiving section; 306: a wireless frame analysis unit; 307: a wired frame transmitting unit; 308: a response control unit; 309: a radio frequency switching unit.

Claims (9)

1. A wireless communication apparatus, wherein the wireless communication apparatus has:

a radio receiving unit configured to receive a radio frame by setting a 1 st mobile radio communication timing, a 2 nd mobile radio communication timing, and a 1 st fixed radio communication timing such that the 1 st mobile radio communication timing and the 2 nd mobile radio communication timing are before the 1 st fixed radio communication timing, the 1 st mobile radio communication timing being a timing for receiving a radio frame from a 1 st mobile radio communication terminal among a plurality of radio communication terminals as a mobile radio communication terminal wirelessly connected to the radio communication apparatus, the 2 nd mobile radio communication timing being a timing for receiving a radio frame from a 2 nd mobile radio communication terminal among the plurality of radio communication terminals as a mobile radio communication terminal wirelessly connected to a radio communication apparatus other than the radio communication apparatus, and the 1 st fixed radio communication timing being a timing for receiving a radio frame from the plurality of radio communication terminals as a mobile radio communication terminal wirelessly connected to the radio communication apparatus Timing of a radio frame of a 1 st fixed wireless communication terminal of the fixed wireless communication terminals connected wirelessly; and

and a switching control unit that controls switching of a connection destination of a radio connection of the 2 nd mobile radio communication terminal when the radio reception unit receives a radio frame from the 2 nd mobile radio communication terminal at the 2 nd mobile radio communication timing.

2. The wireless communication apparatus of claim 1,

the radio receiving unit receives radio frames by repeating a communication cycle including a 1 st mobile radio communication timing corresponding to the number of the 1 st mobile radio communication terminals, a 2 nd mobile radio communication timing corresponding to the number of the 2 nd mobile radio communication terminals, and a 1 st fixed radio communication timing corresponding to the number of the 1 st fixed radio communication terminals.

3. The wireless communication apparatus of claim 1,

the switching control unit performs control of switching a connection destination of the wireless connection of the 2 nd mobile wireless communication terminal from the other wireless communication apparatus to the wireless communication apparatus when the wireless reception unit receives a wireless frame from the 2 nd mobile wireless communication terminal at the 2 nd mobile wireless communication timing.

4. The wireless communication apparatus of claim 1,

the wireless communication device further includes a wireless transmission unit that transmits a response request frame, which is a wireless frame for requesting a response, before the 1 st mobile wireless communication timing and the 2 nd mobile wireless communication timing start,

the radio reception unit receives a response frame, which is a radio frame responding to the response request frame, from the 1 st mobile radio communication terminal at the 1 st mobile radio communication timing,

the radio receiving unit does not receive the response frame from the 2 nd mobile radio communication terminal when the 2 nd mobile radio communication terminal does not need to switch the connection destination of the radio connection at the 2 nd mobile radio communication timing, and receives the response frame from the 2 nd mobile radio communication terminal when the 2 nd mobile radio communication terminal needs to switch the connection destination of the radio connection.

5. The wireless communication apparatus of claim 4,

the radio transmitter does not retransmit the response request frame even when the radio receiver does not receive the response frame from the 2 nd mobile radio communication terminal at the 2 nd mobile radio communication timing, and retransmits the response request frame even when the radio receiver does not receive the response frame from the 1 st mobile radio communication terminal at the 1 st mobile radio communication timing.

6. The wireless communication apparatus of claim 1,

the switching control unit controls switching of the connection destination of the wireless connection of the 1 st mobile wireless communication terminal when the wireless reception unit receives a wireless frame requesting switching of the connection destination of the wireless connection from the 1 st mobile wireless communication terminal at the 1 st mobile wireless communication timing.

7. The wireless communication apparatus of claim 1,

the wireless reception unit does not set a timing for receiving a wireless frame from a 2 nd fixed wireless communication terminal, which is a fixed wireless communication terminal wirelessly connected to the other wireless communication device, among the plurality of wireless communication terminals.

8. A method of wireless communication, wherein,

the wireless communication device as a computer sets a 1 st mobile wireless communication timing, a 2 nd mobile wireless communication timing, and a 1 st fixed wireless communication timing such that the 1 st mobile wireless communication timing and the 2 nd mobile wireless communication timing are before the 1 st fixed wireless communication timing, and receives a wireless frame, wherein the 1 st mobile wireless communication timing is a timing for receiving a wireless frame from a 1 st mobile wireless communication terminal of a plurality of wireless communication terminals as a mobile wireless communication terminal wirelessly connected to the wireless communication device, the 2 nd mobile wireless communication timing is a timing for receiving a wireless frame from a 2 nd mobile wireless communication terminal of the plurality of wireless communication terminals as a mobile wireless communication terminal wirelessly connected to another wireless communication device other than the wireless communication device, and the 1 st fixed wireless communication timing is a timing for receiving a wireless frame from the plurality of wireless communication terminals as a mobile wireless communication terminal wirelessly connected to the wireless communication device And a control unit configured to control switching of a connection destination of a wireless connection of the 2 nd mobile wireless communication terminal when the wireless frame of the 1 st fixed wireless communication terminal to which the wire communication device is wirelessly connected receives the wireless frame from the 2 nd mobile wireless communication terminal at the 2 nd mobile wireless communication timing.

9. A computer-readable recording medium having a wireless communication program recorded thereon, wherein the wireless communication program causes a wireless communication apparatus as a computer to execute:

a wireless reception process of setting a 1 st mobile wireless communication timing, a 2 nd mobile wireless communication timing, and a 1 st fixed wireless communication timing such that the 1 st mobile wireless communication timing and the 2 nd mobile wireless communication timing are before the 1 st fixed wireless communication timing, and receiving a wireless frame, wherein the 1 st mobile wireless communication timing is a timing for receiving a wireless frame from a 1 st mobile wireless communication terminal among a plurality of wireless communication terminals as a mobile wireless communication terminal wirelessly connected to the wireless communication apparatus, the 2 nd mobile wireless communication timing is a timing for receiving a wireless frame from a 2 nd mobile wireless communication terminal among the plurality of wireless communication terminals as a mobile wireless communication terminal wirelessly connected to a wireless communication apparatus other than the wireless communication apparatus, and the 1 st fixed wireless communication timing is a timing for receiving a wireless frame from the plurality of wireless communication terminals as a mobile wireless communication terminal wirelessly connected to the wireless communication apparatus Timing of a radio frame of a 1 st fixed wireless communication terminal of the fixed wireless communication terminals connected wirelessly; and

and a handover control process of controlling handover of a connection destination of a radio connection of the 2 nd mobile radio communication terminal when the 2 nd mobile radio communication timing receives a radio frame from the 2 nd mobile radio communication terminal.

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