JP2010245746A - Radio communication system, and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accelerate channel switching of a radio terminal device. <P>SOLUTION: This radio communication system includes: a repeater having a first communicating section for performing broadcasting on a reference radio channel, a second communicating section for performing radio communication on a radio channel other than the reference radio channel, and a first control section for selecting a radio channel on the basis of communicating states of a plurality of radio channels, setting the selected radio channel to a radio channel of the second communicating section and transmitting information of the set radio channel by the first communicating section when a communicating state of the radio channel of the second communicating section deteriorates; and a radio terminal device having a third communicating section for performing radio communication with the repeater, and a second control section for setting a radio channel of the third communicating section to the reference radio channel to acquire information of a radio channel transmitted from the repeater if the radio communication is disconnected, and changing the radio channel of the third communicating section on the basis of information of the acquired radio channel. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication system and a wireless communication method.

  In recent years, a wireless communication system constituting a star network defined in IEEE 802.15.4 has a relay device (coordinator) serving as the center of the network and a plurality of wireless terminal devices (ends) located around the relay device. Device).

  The relay device selects a channel having the best radio wave condition with the least interference wave among the radio frequency bands that are divided in advance into a plurality of channels when the network is started up. The wireless terminal device performs channel scanning, checks the channel used by the relay device, and tries to join the network.

  The channel used by the relay device can be changed during network operation. For example, when the interference wave increases in the channel being used and the communication quality is deteriorated, the relay device can change to a channel having a better communication quality than the channel being used.

However, when the channel used by the relay device is changed, the wireless terminal device must perform channel scanning again to find a new channel used by the relay device.
In general, a wireless terminal device performs an intermittent operation that enters a sleep state at regular intervals to save power. Moreover, a certain time is required for the channel scan. For this reason, it has been difficult to quickly switch all wireless terminal devices connected to the network to a new channel.

  Therefore, in a wireless communication network system having a tree structure with the parent station at the top, the parent station performs ED scan (Energy Detect Scan), measures information indicating communication quality such as LQI (Link Quality Indicator), and the like. The quality of the communication status is determined based on the measurement result. When the communication status of the frequency channel being used deteriorates, the master station transmits a frequency change notification to the slave station by broadcasting, and changes the frequency channel to be used after broadcasting. When the slave station receives the frequency change notification, the slave station changes the frequency of its own communication. Is disclosed (see Patent Document 1).

JP 2008-187603 A

  However, in Cited Document 1, when a frequency change notification is broadcasted to a slave station (wireless terminal device), a channel whose communication status is deteriorated is used. Therefore, depending on the communication status of the channel, the frequency change notification is used. May not be received by the wireless terminal device. A wireless terminal device that cannot receive a frequency change notification needs to scan all channels to obtain new channel information. Therefore, when the channel used by the relay device is changed, it is still difficult to speed up the channel switching process of the wireless terminal device.

  In view of the above problems, an object of the present invention is to speed up channel switching of a wireless terminal device.

  In order to solve the above problems, the invention according to claim 1 is a wireless communication system including a plurality of wireless terminal devices and a relay device that performs wireless communication with the plurality of wireless terminal devices. A first communication unit that broadcasts to the plurality of wireless terminal devices using a preset wireless channel among the plurality of wireless channels, and a plurality of wireless channels other than the wireless channel set in the first communication unit Any one of the wireless channels is set, a second communication unit that performs wireless communication with the plurality of wireless terminal devices using the set wireless channel, and communication of the wireless channel set in the second communication unit When the situation deteriorates, the communication status of the plurality of wireless channels is detected by the second communication unit, and based on the detected plurality of communication statuses One of the plurality of radio channels is selected, the selected radio channel is set as the radio channel of the second communication unit, and information on the radio channel set in the second communication unit is set in the first communication channel. A first control unit for transmission by one communication unit, wherein the wireless terminal device has any one of the plurality of wireless channels set, and the relay is performed on the set wireless channel. When wireless communication between the third communication unit that performs wireless communication with the device and the third communication unit and the second communication unit of the relay device is interrupted, the wireless channel set in the third communication unit is A wireless channel set in advance in one communication unit is set, information on the wireless channel set in the second communication unit is acquired by the third communication unit, and the acquired wireless channel is acquired. It is characterized by having a second control unit for changing a radio channel set to the third communication unit based on the information of the panel, the.

  According to a second aspect of the present invention, in the wireless communication system according to the first aspect, the first control unit has an electric field strength of a wireless channel set in the second communication unit equal to or greater than a preset threshold value. In this case, it is determined that the communication status of the wireless channel set in the second communication unit has deteriorated.

  According to a third aspect of the present invention, in the wireless communication system according to the first or second aspect, when the communication state of a wireless channel set in the second communication unit deteriorates, the first control unit The two communication units detect the electric field strengths of a plurality of radio channels excluding the radio channel set in the first communication unit as the communication status, and correspond to the smallest electric field strength among the detected plurality of electric field strengths. It is characterized by selecting a radio channel.

  Invention of Claim 4 is a radio | wireless communications system as described in any one of Claim 1 to 3. WHEREIN: The said 2nd control part is transmitted from the said 2nd communication part of the said relay apparatus by the said 3rd communication part. When the beacon signal to be received cannot be received, it is determined that the wireless communication is interrupted.

  The invention described in claim 5 excludes a first communication unit that broadcasts to a plurality of wireless terminal devices using a preset wireless channel among a plurality of wireless channels, and a wireless channel set in the first communication unit. A relay device having a second communication unit in which any one of the plurality of wireless channels is set and wirelessly communicates with the plurality of wireless terminal devices on the set wireless channel; One of the wireless channels is a wireless communication method with a wireless terminal device in which one wireless channel is set and has a third communication unit that performs wireless communication with the relay device on the set wireless channel, When the communication status of the wireless channel set in the second communication unit of the relay device deteriorates, the communication status of the plurality of wireless channels A step of detecting by the second communication unit; a step of selecting any one of the plurality of wireless channels based on the detected plurality of communication states; and A step of setting a wireless channel of the communication unit, a step of transmitting information of the wireless channel set in the second communication unit by the first communication unit, a step of transmitting the third communication unit of the wireless terminal device and the relay device When wireless communication with the second communication unit is interrupted, the step of setting the wireless channel of the third communication unit to the preset wireless channel, and the information of the wireless channel set to the second communication unit A step of acquiring by the third communication unit, and a step of changing the wireless channel set in the third communication unit based on the acquired wireless channel information It is characterized in that it comprises a.

  According to the present invention, it is possible to speed up channel switching of a wireless terminal device.

It is a schematic block diagram of a radio | wireless communications system. It is a schematic block diagram of a relay apparatus. It is a figure which shows the example of a beacon frame. It is a schematic block diagram of a radio | wireless terminal apparatus. It is a flowchart of a wireless channel switching process. It is a flowchart of a wireless channel change process. It is a sequence diagram which shows the operation example with a relay apparatus and a radio | wireless terminal apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. The embodiment of the present invention shows the most preferable mode of the present invention, and the terminology of the present invention is not limited to this.

First, the configuration will be described.
FIG. 1 shows a schematic configuration diagram of a wireless communication system A in the present embodiment.

  As shown in FIG. 1, a wireless communication system A includes a relay device 1 connected to another relay device or an external device via a communication network N, and a plurality of wireless terminals connected to the relay device 1 via a radio The apparatus 2 is provided.

  The wireless communication system A in the present embodiment is based on the IEEE 802.15.4 standard. In this case, the relay device 1 corresponds to a coordinator, and the wireless terminal device 2 corresponds to an end device.

In FIG. 2, the schematic block diagram of the relay apparatus 1 is shown.
As shown in FIG. 2, the relay device 1 includes a control unit 10, a storage unit 11, a terminal information memory 12, a beacon transmission timer 13, a first communication unit 14, a second communication unit 15, and a wired I / F (InterFace). The unit 16 and the buffer 17 are provided, and each unit is electrically connected.

  The control unit 10 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The control unit 10 reads various programs stored in the storage unit 11 and the terminal information memory 12, programs, tables, and data specified from various tables and data, and stores them in the work area of the RAM or the storage unit 11. Expands and executes various processes in cooperation with the program, stores the processing results in the RAM or a predetermined area of the storage unit 11 or the terminal information memory 12, and instructs each unit in the relay device 1 Thus, the overall operation of the relay device 1 is comprehensively controlled.

  The control unit 10 generates a beacon signal for broadcasting, and periodically transmits the generated beacon signal to the first communication unit 14 using a preset wireless channel (reference wireless channel).

  As the reference radio channel, for example, in IEEE 802.15.4, any one of the 16 radio channels of ch11 to ch26 obtained by dividing the 2.4 [GHz] band into 16 is one of the radio channels such as an interference wave. It is preferable that the wireless channel be least susceptible to the influence of the above. In the present embodiment, description will be given using ch 26 as an example of a preset wireless channel.

The control unit 10 switches the radio channel of the second communication unit 15 according to the communication status of the radio channel set in the second communication unit 15. Moreover, the control part 10 produces | generates a beacon signal and a data signal, and transmits the produced | generated beacon signal regularly.
The wireless channel that can be set in the second communication unit 15 is any one of a plurality of wireless channels excluding the reference wireless channel set in the first communication unit 14.

  The beacon signal is packet data transmitted from the relay device 1 at regular intervals, and is for synchronizing the wireless terminal device 2 connected to the wireless communication system A and the relay device 1.

FIG. 3 shows an example of a beacon frame in the present embodiment.
As shown in FIG. 3, the beacon signal has an MHR (MAC (Media Access Control) header) area B1, a MAC payload area B2, and an MFR (MAC Footer) area B3, and is based on the IEEE 802.15.4 standard. It is based on.

  The MHR area B1 includes a frame control B11, an address area B12, and the like. The MAC payload area B2 includes an SS (Superframe Specification) B21, a GTS (Guaranteed Time Slot) field B22, a PA (Pending Address) field B23, a beacon payload B24, and the like.

  The SSB 21 is a detailed information field of a superframe, and defines a beacon transmission interval and a beacon communication method for performing time management when a beacon is received. The GTS field B22 includes information on a communication method (for example, GTS) guaranteed by the wireless terminal device. When there is data to be transmitted to the wireless terminal device, the PA field B23 includes terminal identification information (node address) for identifying the wireless terminal device that transmits the data.

The beacon payload B24 includes a payload area of about 50 bytes.
When the beacon signal is used when broadcasting, the beacon payload B24 includes a DATE area B24a, a COM_NCH area B24b, and a CH area B24c. Date / time information is stored in the DATE area B24a. In the COM_NCH area B24b, a command ID indicating information on a radio channel currently used by the second communication unit 15 is stored in the next area. The CH area B24c stores radio channel information.

  In addition, when the communication status of the wireless channel set in the second communication unit 15 deteriorates, the control unit 10 reads the wireless channel switching processing program and various data from the storage unit 11 and executes the wireless channel switching processing. 1 functions as a control unit.

  In the wireless channel switching process, when the communication state of the wireless channel set in the second communication unit 15 deteriorates, the second communication unit 15 detects the communication state of a plurality of wireless channels, and the detected plurality of One of the plurality of wireless channels is selected based on the communication status. Then, the selected radio channel is set as the radio channel of the second communication unit 15, and information on the radio channel set in the second communication unit 15 is transmitted by broadcast using the beacon signal by the first communication unit 14.

  The control unit 10 causes the second communication unit 15 to periodically scan the electric field strength of the wireless channel currently set in the second communication unit 15. Since it is known that the throughput changes in accordance with the electric field strength, the communication status can be determined by scanning the electric field strength. Thus, the control unit 10 determines that the communication status of the wireless channel set in the second communication unit 15 has deteriorated when the result obtained by the scan is equal to or greater than a preset threshold value.

  When the communication state of the wireless channel set in the second communication unit 15 deteriorates, the control unit 10 selects the first communication channel from the plurality of wireless channels, and the first communication unit 15 The field strength of a plurality of wireless channels excluding the wireless channel set in the communication unit 14 is detected as a communication status, and the wireless channel corresponding to the smallest field strength is selected from the detected plurality of field strengths.

  The storage unit 11 is composed of a magnetic or optical recording medium or a non-volatile memory that can be electrically erased and rewritten, such as a semiconductor. The storage unit 11 is fixedly attached to the relay device 1 or is detachably mounted. It is what is done. The storage unit 11 stores in advance a wireless channel switching program executed by the control unit 10, various programs, various tables and data used in these programs, and the like.

  The terminal information memory 12 is composed of a memory that can be electrically erased and rewritten. The terminal information memory 12 stores information such as the node address of the wireless terminal device 2 existing within the communicable area of the relay device 1 itself.

  The beacon transmission timer 13 is a timer that times the beacon transmission interval, and outputs a beacon transmission timing signal indicating that the time has reached the transmission interval to the control unit 10.

  The first communication unit 14 includes a modulation circuit, a demodulation circuit, an RF (Radio Frequency) circuit, an antenna 14a, and the like, and broadcasts on a reference wireless channel.

  The first communication unit 14 adjusts the transmission power of the packet, encodes data to be transmitted in accordance with an instruction from the control unit 10, forms a packet, modulates the formed packet, and performs antenna 14a. The packet is transmitted to the wireless terminal device 2 via The first communication unit 14 adjusts the reception sensitivity of the packet, demodulates the packet received via the antenna 14a, and outputs data obtained by analyzing the demodulated packet to the control unit 10. To do.

  The second communication unit 15 includes a modulation circuit, a demodulation circuit, an RF (Radio Frequency) circuit, an antenna 15a, and the like, and performs wireless communication using any one of a plurality of wireless channels excluding the reference wireless channel.

  Similar to the first communication unit 14, the second communication unit 15 also adjusts the transmission power and reception sensitivity of the packet. The second communication unit 15 encodes data to be transmitted according to an instruction from the control unit 10 to form a packet, modulates the formed packet, and transmits the packet to the wireless terminal device 2 via the antenna 14a. Is transmitted, the packet received via the antenna 14a is demodulated, and the data obtained by analyzing the demodulated packet is output to the control unit 10.

  In addition, the second communication unit 15 scans the electric field strength of a plurality of radio channels (for example, all 16 channels), and outputs the result obtained by the scan to the storage unit 11.

  The wired I / F 16 performs communication control for communicating with another relay device 1 or an external device connected via the communication network N by a predetermined communication method.

  The buffer 17 temporarily stores data received via the wired I / F 16.

FIG. 4 shows a schematic configuration diagram of the wireless terminal device 2.
As shown in FIG. 4, the wireless terminal device 2 includes a control unit 20, a storage unit 21, an address memory 22, an activation timer 23, a power supply control unit 24, a display control unit 25 a, a display unit 25 b, and a third communication unit 26. Etc., and each part is electrically connected. The wireless terminal device 2 includes a battery B, and power is supplied from the battery B to each unit in response to a control signal from the power supply control unit 24.

  The control unit 20 includes a CPU, a ROM, a RAM, and the like, reads out various programs stored in the storage unit 21, various programs and tables and data specified from various tables and data, and stores them in the RAM or the storage unit 21. In the work area, execute various processes in cooperation with the above program, store the processing results in a predetermined area of the RAM or storage unit 21, and instruct each unit in the wireless terminal device 2, The overall operation of the wireless terminal device 2 is comprehensively controlled.

  When the wireless communication with the relay device is interrupted, the control unit 20 functions as a second control unit that reads out the wireless channel change processing program and various data from the storage unit 21 and executes the wireless channel change processing.

  In the wireless channel change process, the reference wireless channel is set as the wireless channel of the third communication unit 26 when wireless communication with the relay device is interrupted. And the information of the wireless channel set in the 2nd communication part 15 transmitted by broadcast from the 1st communication part 14 of the relay apparatus 1 is acquired by the 3rd communication part 26, The said 2nd communication part 15 is acquired. The wireless channel of the third communication unit is changed based on the set wireless channel information.

  The storage unit 21 is composed of a non-volatile memory that can be electrically erased and rewritten, such as a magnetic or optical recording medium or a semiconductor, and is provided in the wireless terminal device 2 or is detachable. It is to be attached. The storage unit 21 stores in advance various programs executed by the control unit 20 and various tables and data used in these programs.

  The address memory 22 is composed of a nonvolatile memory that can be electrically erased and rewritten. The address memory 22 stores terminal identification information (node address) for identifying the wireless terminal device 2 itself.

  The activation timer 23 is a timer for timing the activation timing (activation time) of the third communication unit 26 calculated by the control unit 20, and outputs an activation timing signal indicating that the activation timing has been reached to the control unit 20. .

  The power control unit 24 controls the power supply of the entire wireless terminal device 2 in accordance with an instruction from the control unit 20, and supplies power from the battery B to each unit in the wireless terminal device 2.

  The battery B is, for example, a primary battery such as an alkaline battery or a manganese battery, or a secondary battery such as a nickel cadmium battery, a nickel hydrogen battery, or a lithium ion battery.

  The display control unit 25a displays various information on the display unit 25b in accordance with the display instruction input from the control unit 20.

  The display unit 25b is configured by an LCD (Liquid Crystal Display), an EL (Electro Luminescence) display, or the like, and displays various screens on the display according to a signal input from the display control unit 25a.

  The third communication unit 26 includes a wireless transmission unit 26a, a wireless reception unit 26b, a SW (switching unit) 26c, an antenna 26d, and the like, and performs wireless communication with the relay device 1.

  The wireless transmission unit 26a includes a modulation circuit, an RF (Radio Frequency) circuit, and the like, adjusts the transmission power of the packet, encodes the data to be transmitted according to an instruction from the control unit 20, and transmits the packet. The packet is modulated, and the packet is transmitted to the relay apparatus 1 via the antenna 26d.

  The radio reception unit 26b includes a demodulation circuit, an RF circuit, and the like, and is obtained by adjusting the reception sensitivity of the packet, demodulating the packet received via the antenna 26d, and analyzing the demodulated packet. The data is output to the control unit 20.

  The SW 26c is provided between the antenna 26d and the wireless transmission unit 26a or the wireless reception unit 26b. According to an instruction from the control unit 20, the SW 26c transmits a packet from the wireless transmission unit 26a or receives a packet from the antenna 26d. Switch.

  The antenna 26d transmits a packet according to the set transmission power or receives a packet according to the set reception sensitivity.

Next, the operation of the present embodiment will be described.
FIG. 5 shows a flowchart of the radio channel switching process executed in the relay apparatus 1. Note that the processing shown in FIG. 5 is executed in cooperation with the control unit 10 and each unit in the relay apparatus 1 and is executed while power is being supplied to the relay apparatus 1.

  The control unit 10 detects the communication status of the wireless channel set in the second communication unit 15 (step S1). In step S1, according to the instruction from the control unit 10, for example, the second communication unit 15 detects the electric field strength per unit time of the wireless channel currently set in itself. That is, the electric field strength is detected as the communication status. The detection result is stored in the storage unit 11.

  The control unit 10 determines whether or not the communication status detected in step S1 has deteriorated (step S2). In step S2, it is determined whether or not the electric field strength detected in step S1 is greater than or equal to a preset threshold value. If the detected electric field strength is greater than or equal to the threshold value, it is determined that the communication status has deteriorated.

  If the communication status has not deteriorated (step S2; NO), the control unit 10 returns to the process of step S1. When the communication state deteriorates (step S2; YES), the control unit 10 causes the second communication unit to perform a radio band scan (step S3).

  The control unit 10 changes the setting of the radio channel of the second communication unit 15 based on the result of the radio band scan in step S3 (step S4).

  As an example of steps S3 and S4, the electric field strength for every wireless channel in the wireless band is detected, and the electric field strength of each wireless channel is stored in the storage unit 11 (step S3). In step S4, the wireless channel with the lowest electric field strength among the electric field strengths stored in the storage unit 11 is set as the wireless channel of the second communication unit 15 (step S4). It is good.

  As another example of steps S3 and S4, the electric field strength for every radio channel in the radio band is detected by the second communication unit 15 a plurality of times continuously in a preset cycle, and each cycle for each radio channel is detected. The electric field strength is stored in the storage unit 11 in time series (step S3). Then, the moving average value of the latest electric field strength among the electric field strengths of a plurality of periods is calculated for each wireless channel, and the wireless channel corresponding to the smallest moving average value among the calculated moving average values of each wireless channel is It is set as the radio channel of the second communication unit 15 (step S4). It is good. Instead of the moving average value, an average value of the electric field strengths of a plurality of periods may be calculated.

  The control unit 10 notifies the first communication unit 14 of the wireless channel information of the second communication unit 15 set in step S4 (step S5).

  The control unit 10 causes the first communication unit 14 to update the information on the radio channel of the second communication unit 15 notified to the beacon payload of the beacon signal broadcast from the first communication unit 14, and updates the information from the first communication unit 14. The transmitted beacon signal is broadcasted (step S6), and the process returns to step S1.

  FIG. 6 shows a flowchart of the wireless channel change process executed in the wireless terminal device 2. The process shown in FIG. 6 is executed by the cooperation of the control unit 20 and each unit in the wireless terminal device 2 and is executed while power is supplied to the wireless terminal device 2. is there.

  After establishing communication with the relay device 1, the wireless terminal device 2 performs an intermittent operation according to a beacon signal transmitted from the relay device 1 at regular intervals. The wireless terminal device 2 performs an operation of reducing power consumption as much as possible by turning off its own power supply when communication is not necessary. However, the wireless terminal device 2 wakes up to receive a beacon signal, and sends a beacon signal to itself. When there is a data transmission / reception request, an operation according to the request is performed.

  The control unit 20 determines whether or not the beacon signal has been received from the relay device 1 in the wireless channel currently set in the third communication unit 26 (step S11).

  In step S11, for example, the IEEE 802.15.4 MAC layer has a function of communicating an error “BEACON LOST”, and is determined using this function. Since “BEACON LOST” occurs when a beacon signal cannot be received for a certain period, the control unit 20 determines whether or not “BEACON LOST” is communicated from the third communication unit 26. The “certain period” is defined in IEEE 802.15.4 as a period represented by the product of the beacon transmission interval and the number of times the beacon has failed to be received.

  When the beacon signal can be received (step S11; YES), the control unit 20 executes a beacon reception process (step S12) and returns to the process of step S11.

  When the beacon signal cannot be received (step S11; NO), the wireless channel set in the third communication unit 26 is changed to the reference wireless channel (step S13), and the beacon signal can be received from the relay device 1 on the reference wireless channel. It is determined whether or not (step S14). In step S14, the determination is made using “BEACON LOST” as in step S11.

  When the beacon signal can be received (step S14; YES), the control unit 20 acquires information on the wireless channel included in the beacon payload of the received beacon signal (step S15). The control unit 20 changes the wireless channel of the third communication unit 26 based on the acquired wireless channel information (step S16), and returns to the process of step S11.

  When the beacon signal cannot be received (step S14; NO), the control unit 20 causes the third communication unit 26 to scan all wireless channels. A wireless channel connectable to the relay device 1 is searched (step S17). Then, the control unit 20 changes the radio channel of the third communication unit 26 to the radio channel found in step S17 (step S18), and returns to the process of step S11.

FIG. 7 shows a sequence diagram showing an operation example of relay apparatus 1 and wireless terminal apparatus 2 in the present embodiment.
It is assumed that ch26 is set as the reference radio channel in the first communication unit of the relay apparatus 1, and ch11 is initially set in the second communication unit. It is assumed that the wireless terminal device 2 is performing wireless communication with the second communication unit of the relay device 1 at ch11.
In addition, the first communication unit periodically transmits a beacon signal, and the second communication unit periodically transmits a beacon signal.

When receiving the beacon signal transmitted in ch11, the wireless terminal device 2 executes a beacon reception process.
As the beacon reception processing here, a data request signal is transmitted from the third communication unit of the wireless terminal device 2 to the second communication unit of the relay device 1. And a 3rd communication part receives the ACK signal transmitted from the 2nd communication part of the relay apparatus 1, and receives a data signal. Then, an ACK signal is transmitted from the third communication unit to the second communication unit of the relay device 1 (step S21).

  When the relay device 1 determines that the communication information of the radio channel of the second communication unit has deteriorated, the relay device 1 performs a radio band scan to change the setting of the radio channel of the second communication unit. Here, it is assumed that the radio channel of the second communication unit is changed from ch11 to ch13 (step S22). Also, the beacon signal transmitted from the first communication unit is updated, and the information on the radio channel of the second communication unit included in the beacon signal is rewritten (step S23). The updated beacon signal is broadcast from the first communication unit.

  Since the wireless channel of the second communication unit of the relay device 1 has been changed, the wireless terminal device 2 cannot receive the beacon signal at ch11 (step S24). Therefore, the wireless terminal device 2 changes and sets the wireless channel of the third communication unit from ch11 to ch26 (step S25), and waits for reception of a beacon signal transmitted from the relay device 1 at ch26.

  When the wireless terminal device 2 receives the beacon signal from the relay device 1 in ch26, the wireless terminal device 2 acquires information on the wireless channel (in this case, information indicating ch13) included in the received beacon signal (step S26), and the acquired wireless channel The wireless channel of the third communication unit is changed according to the information. Here, the radio channel of the third communication unit is changed from ch26 to ch13 (step S27).

  After that, when receiving the beacon signal transmitted from the relay device 1 at ch13, the wireless terminal device 2 executes a beacon reception process (step S28).

  In addition to the second communication unit 15 in which the relay device 1 performs wireless communication with the wireless terminal device 2, the relay device 1 includes a first communication unit 14 dedicated to broadcast transmission of information on the wireless channel of the second communication unit 15. When the communication status of the wireless channel performing the wireless communication deteriorates and the communication is interrupted when the first second communication unit 15 and the third communication unit 26 of the wireless terminal device 2 perform the wireless communication, The wireless terminal device 2 switches the wireless channel set in the third communication unit 26 to the wireless channel (reference wireless channel) set in the first communication unit 14 of the relay device 1 and sets the first communication unit. 14 acquires the information of the wireless channel newly set in the second communication unit 15 from the beacon signal transmitted from 14, and changes the wireless channel of the third communication unit 26 to the acquired wireless channel. Kill.

  Therefore, when the communication status of the wireless channel being used deteriorates, the relay device 1 can immediately change the wireless channel regardless of whether or not the wireless terminal device 2 is connected. When the wireless communication with 1 is interrupted, the information on the new wireless channel of the relay device 1 can be acquired without scanning all the channels. Accordingly, it is possible to speed up channel switching of the wireless terminal device 2.

  Moreover, the relay apparatus 1 deteriorates the communication status when the electric field strength of the wireless channel set in the second communication unit 15 is equal to or higher than a preset threshold value as the determination of the communication status of the second communication unit 15. Can be determined.

  When the communication status of the radio channel of the second communication unit 15 deteriorates, the relay device 1 supports the smallest electric field strength among the electric field strengths of a plurality of radio channels excluding the radio channel set in the first communication unit 14 The wireless channel to be selected can be selected as a new wireless channel of the second communication unit 15, and the wireless channel with the best communication status (throughput) can be selected.

  Further, the wireless terminal device 2 cannot receive the beacon signal transmitted from the second communication unit 15 of the relay device 1 by the third communication unit 26 (when “BEACON LOST” is communicated from the third communication unit 26). It can be determined that the wireless communication has been interrupted.

DESCRIPTION OF SYMBOLS 1 Relay apparatus 2 Radio | wireless terminal apparatus 10 Control part 11 Memory | storage part 12 Terminal information memory 13 Beacon transmission timer 14 1st communication part 14a Antenna 15 2nd communication part 15a Antenna 16 Wired I / F
17 Buffer 20 Control unit 21 Storage unit 22 Address memory 23 Startup timer 24 Power supply control unit 25a Display control unit 25b Display unit 26 Third communication unit 26a Wireless transmission unit 26b Wireless reception unit 26c SW
26d Antenna A Wireless communication system B1 MHR area B2 MAC payload area B3 MFR area B11 Frame control B12 Address area B21 SS
B22 GTS field B23 PA field B24 Beacon payload B24a DATE area B24b COM_NCH area B24c CH area N Communication network

Claims (5)

In a wireless communication system comprising a plurality of wireless terminal devices and a relay device that performs wireless communication with the plurality of wireless terminal devices,
The relay device is
A first communication unit that broadcasts to the plurality of wireless terminal devices on a preset wireless channel among the plurality of wireless channels;
One of the plurality of wireless channels excluding the wireless channel set in the first communication unit is set, and wireless communication is performed with the plurality of wireless terminal devices using the set wireless channel. A second communication unit;
When the communication status of the radio channel set in the second communication unit is deteriorated, the communication status of the plurality of radio channels is detected by the second communication unit, and based on the detected plurality of communication statuses One of the plurality of radio channels is selected, the selected radio channel is set as the radio channel of the second communication unit, and information on the radio channel set in the second communication unit is set in the first channel. A first control unit to be transmitted by the communication unit;
Have
The wireless terminal device
Any one of the plurality of wireless channels is set, and a third communication unit that performs wireless communication with the relay device using the set wireless channel;
When wireless communication between the third communication unit and the second communication unit of the relay device is interrupted, a wireless channel set in the third communication unit is set to a wireless channel preset in the first communication unit Then, the wireless channel information set in the second communication unit is acquired by the third communication unit, and the wireless channel set in the third communication unit is changed based on the acquired wireless channel information. A second control unit;
Having
A wireless communication system. The first controller is
When the electric field strength of the wireless channel set in the second communication unit is equal to or greater than a preset threshold, it is determined that the communication status of the wireless channel set in the second communication unit has deteriorated;
The wireless communication system according to claim 1. The first controller is
When the communication status of the radio channel set in the second communication unit deteriorates, the electric field strengths of a plurality of radio channels excluding the radio channel set in the first communication unit by the second communication unit are Detecting a situation and selecting a radio channel corresponding to the smallest electric field strength among the detected electric field strengths;
The wireless communication system according to claim 1, wherein The second controller is
When the third communication unit cannot receive a beacon signal transmitted from the second communication unit of the relay device, it is determined that the wireless communication has been interrupted;
The wireless communication system according to any one of claims 1 to 3, wherein: Any one of a first communication unit that broadcasts to a plurality of wireless terminal devices using a preset wireless channel among a plurality of wireless channels, and a plurality of wireless channels excluding the wireless channel set in the first communication unit A relay device having a second communication unit configured to wirelessly communicate with the plurality of wireless terminal devices through the set wireless channel, and one of the plurality of wireless channels is one A wireless communication method with a wireless terminal device having a third communication unit in which a wireless channel is set and wireless communication is performed with the relay device using the set wireless channel,
A step of causing the second communication unit to detect a communication state of the plurality of wireless channels when a communication state of the wireless channel set in the second communication unit of the relay device deteriorates;
Selecting any one of the plurality of wireless channels based on the detected plurality of communication conditions;
Setting the selected wireless channel as the wireless channel of the second communication unit;
Transmitting the information of the wireless channel set in the second communication unit by the first communication unit;
When wireless communication between the third communication unit of the wireless terminal device and the second communication unit of the relay device is interrupted, setting a wireless channel of the third communication unit to the preset wireless channel;
Acquiring the information of the wireless channel set in the second communication unit by the third communication unit;
Changing the wireless channel set in the third communication unit based on the acquired wireless channel information;
Including,
A wireless communication method characterized by the above.

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