JP2019216301A - Beacon transmission terminal, beacon reception terminal, and radio communication system - Google Patents

Abstract

To implement a communication system that avoids increase in a communication delay time and a communication disabled state being caused by radio wave interference with another radio communication system installed in the same vehicle and another vehicle.SOLUTION: A radio communication system, every time a communication channel is changed over, takes, in predetermined order, one of a plurality of radio terminals as a beacon transmission terminal and takes the remaining radio terminals as a beacon reception terminal. The beacon transmission terminal makes a start beacon include interference channel skip information on a communication channel in which interference has occurred and reset information for resetting a timer unit of the beacon reception terminal; makes an end beacon include the interference channel skip information on the communication channel in which interference has occurred and channel changeover information representing timing for changing over the communication channel; and, when no end beacon can be received from the other beacon transmission terminals, makes the interference channel skip information include communication channel information on a communication channel for the end beacon.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a beacon transmitting terminal, a beacon receiving terminal, and a wireless communication system that avoid an increase in communication delay time and a communication disabled state due to radio wave interference with another wireless communication system mounted in the same vehicle and another vehicle.

  2. Description of the Related Art Conventionally, a method has been proposed for avoiding the occurrence of radio wave interference with a wireless device of another wireless communication system.

For example, Patent Literature 1 proposes a method in which a control device is arranged in a wireless network including one or more terminal devices, and the control device controls wireless communication using a plurality of frequency channels.
The control device includes a wireless reception unit, a quality determination unit, and a beacon generation unit. The wireless receiving unit is capable of receiving wireless signals of a plurality of frequency channels, and based on the reception state of the wireless signal received by the wireless receiving unit, the quality determining unit determines an available frequency channel, and Determine the order of use.
Then, the beacon generation unit generates a beacon including the use order information of the frequency channel, and transmits the beacon to the terminal device. The channel setting unit of the terminal device that has received the beacon sets the frequency channel to be used according to the use order information (see FIG. 23 (FIG. 14 of Patent Document 1)).
In a superframe period including an active period in which wireless communication can be performed and an inactive period in which wireless communication is not performed, the active period is divided into a plurality of beacon transmission periods, and beacons are periodically transmitted during the beacon transmission period. It is transmitted (see FIG. 20 (FIG. 4 of Patent Document 1), FIG. 21 (FIG. 6 of Patent Document 1), and FIG. 22 (FIG. 6 of Patent Document 1)).

In addition, for example, Patent Literature 2 proposes a system using a system in which communication is performed by temporarily using a frequency band that is not allocated to itself. That is, this is a system in which communication is performed by sharing a part of a license band assigned to a wireless communication system different from the own system. Specifically, before starting communication, the first carrier sense is performed on predetermined L (L ≧ 2) frequency bands, and M frequency bands are selected from among them, and the time slot is selected. , The second carrier sense is performed on M (L ≧ M ≧ 2) frequency bands, and a frequency band to be used for transmission is determined from unused frequency bands. (See FIG. 24 (FIG. 7 of Patent Document 2) and FIG. 25 (FIG. 8 of Patent Document 2)). At this time, if the previously used frequency band is among the final candidates, that frequency band is used. Alternatively, a frequency band that is frequently used is preferentially used.
Note that the wireless terminal includes a matched filter or the like, calculates a correlation value between the same signal sequence as a known sequence stored in advance and a leading sequence of a received signal, and specifies a frequency band used for transmission. (See FIG. 26 (FIG. 9 of Patent Document 2)).

Also, for example, in Patent Document 3, in a distributed autonomous wireless communication network that does not require a specific control station, a specific channel is periodically changed in a communication environment in which a plurality of channels are prepared. A method has been proposed in which communication can be performed on another communication channel even if the communication condition of the channel is poor.
In other words, if communication is performed while staying on the same channel, communication will not be possible if the channel is in poor communication conditions due to interference, etc.By switching between multiple channels and communicating, the effects of channels with poor communication conditions can be avoided. it can.
Therefore, at the transmission timing of each wireless terminal, a beacon is transmitted before data transmission to synchronize the wireless terminals. Immediately after transmitting the beacon, the wireless terminal that transmitted the beacon is given a communication priority assignment section, and after a certain period of time, other wireless terminals can transmit (FIG. 27 (see FIG. 3 of Patent Document 3)). ), FIG. 28 (see FIG. 7 of Patent Document 3)).
In addition, since the channel is changed regularly, a mechanism for determining and notifying a communication channel between terminals is not required, and the operation is simplified (see FIG. 29 (FIG. 13 of Patent Document 3)).

International Publication No. 2010/007738 JP-A-2007-30421 JP 2005-079985 A

However, according to the disclosures of Patent Literature 1, Patent Literature 2 and Patent Literature 3, it is possible to independently avoid the frequency band receiving the interference, increase the communication delay time when radio wave interference occurs for a long time, and disable communication. In some cases, it is difficult to avoid the state, and an object of the present invention is to provide means for solving such a problem.

In order to solve the above problems, the present invention employs the following configuration.
That is, the invention according to claim 1 provides a beacon of a wireless communication system in which one of a plurality of wireless terminals is a beacon transmitting terminal in a predetermined order each time a communication channel is switched, and the remaining wireless terminals are beacon receiving terminals. A transmitting terminal,
A beacon generator for generating a start beacon and an end beacon,
A communication unit for transmitting and receiving the start beacon, data information and the end beacon,
A timer unit that measures a communication channel switching cycle of the communication unit,
A channel switching unit that switches the communication channel of the communication unit according to a predetermined rule in accordance with the switching cycle of the communication channel,
The beacon generation unit, the start beacon includes interference channel skip information including communication channel information of the communication channel that has caused interference, and reset information for resetting a timer unit of a beacon receiving terminal that receives the start beacon. In the termination beacon, interference channel skip information including communication channel information of the communication channel that caused the interference, and channel switching information indicating the timing of switching the communication channel are included, and the termination beacon is transmitted from another beacon transmitting terminal. If reception is not possible, the communication channel information of the communication channel of the end beacon is included in the interference channel skip information,
The interference channel skip information of the start beacon includes interference channel skip information of the own wireless terminal and interference channel skip information received from another beacon transmitting terminal,
The interference channel skip information of the end beacon includes interference channel skip information of the start beacon and interference channel skip information of the own wireless terminal,
The communication unit transmits the start beacon before the start of a specified time that is the transmission and reception period of the data information, and transmits the end beacon when the specified time ends,
The channel switching unit, at the end of the switching cycle of the communication channel from the timing of starting transmission of the start beacon to the timing of completion of the transmission of the end beacon, the interference channel skip information included in the end beacon, The communication channel is switched based on the predetermined rule, and the timer unit is reset.

According to the above configuration, the beacon transmission terminal switches the communication channel based on the interference channel skip information included in the end beacon and a predetermined rule at the end of the communication channel switching cycle, The communication channel that is a band can be avoided independently. Further, it is possible to synchronize with the beacon receiving terminal that has received the interference channel skip information included in the end beacon and avoid a communication channel that is a frequency band that is receiving interference. Furthermore, even when radio interference occurs on a specific communication channel for a long time and the beacon transmitting terminal cannot transmit an end beacon on the specific communication channel, interference channel skip information for skipping the specific communication channel on another communication channel. , The beacon transmitting terminal can switch the communication channel by skipping the specific communication channel in synchronization with the beacon receiving terminal. Therefore, by avoiding a communication channel in which radio wave interference has been occurring for a long time, it is possible to avoid an increase in communication delay time and a state in which communication is disabled.
Also, even if the timing of the transmission frame of the beacon receiving terminal is shifted by a predetermined period, the reset information for resetting the timer unit of the beacon receiving terminal included in the first start beacon of the transmission frame and the reset information included in the last end beacon of the transmission frame Re-synchronization with the beacon receiving terminal can be performed with the channel switching information.
Furthermore, when the timing of switching the communication channel of the beacon transmitting terminal is advanced, the beacon receiving terminal receives the end beacon transmitted at the advanced switching timing, and the beacon receiving terminal switches the communication channel, thereby transmitting the beacon. The terminal can resynchronize with the beacon receiving terminal.

In order to solve the above problem, the invention according to claim 2 is the beacon transmission terminal according to claim 1, wherein the communication unit is transmitted from the beacon reception terminal between the start beacon and the end beacon. Receive further intermediate beacons,
The communication unit further includes a beacon analysis unit that analyzes the interference channel skip information included in the intermediate beacon received,
If the communication channel information of the communication channel having the interference included in the interference channel skip information analyzed by the beacon analysis unit is not included in the interference channel skip information of the start beacon, the beacon generation unit is The communication channel information is included in the interference channel skip information of the end beacon.
If a specific beacon receiving terminal receives interference without interference from the beacon transmitting terminal even on the same communication channel due to an installation location or the like, the beacon transmitting terminal cannot transmit an end beacon including the interference information. However, according to the above configuration, the next beacon transmitting terminal recognizes the interference information of the previous communication channel by the intermediate beacon of the beacon receiving terminal that has received the interference, and transmits the end beacon including the interference information. Will be able to do it. Therefore, the beacon transmitting terminal and the beacon receiving terminal included in the wireless communication system can skip the interference channel and continue to synchronize.

In order to solve the above problem, the invention according to claim 3 is the beacon transmission terminal according to claim 1 or 2, wherein the communication unit receives the end beacon transmitted by another beacon transmission terminal. The channel switching unit switches the communication channel based on the interference channel skip information included in the end beacon and the predetermined rule at the end of receiving the channel switching information included in the end beacon, The timer unit is reset.
If the switching timing of the communication channel of the beacon transmitting terminal is delayed within the length of the transmission frame that is the data information transmission / reception period, the beacon receiving terminal that has already switched the communication channel cannot receive the end beacon. Therefore, the beacon transmitting terminal cannot be synchronized with the beacon receiving terminal. However, according to the above configuration, when the beacon transmitting terminal receives an end beacon from another beacon communication terminal on the switched communication channel, it switches the communication channel at the reception end timing of the end beacon and resets the timer. As a result, the beacon communication terminal can re-synchronize with another beacon communication terminal and the beacon receiving terminal.

According to a fourth aspect of the present invention, in the beacon transmitting terminal according to any one of the first to third aspects, the start beacon further includes transmission request information, and the transmission request information is activated. If the transmission request information is not activated, the beacon transmitting terminal is provided with a priority processing period for transmitting data information preferentially after transmitting the start beacon, and if the transmission request information is not activated, The transmission of data information by the beacon receiving terminal becomes possible without providing a priority processing period.
According to the above configuration, only when there is a transmission request to the beacon transmission terminal, the priority processing period is assigned. Therefore, when there is no transmission request to the beacon transmission terminal, other wireless terminals can communicate efficiently. .

According to a fifth aspect of the present invention, in the beacon transmission terminal according to any one of the first to fourth aspects, the interference channel skip information includes communication channel information of a communication channel having interference. In the case where the communication channel of the switching destination is in the order of the communication channel having the interference, the communication channel before the communication channel having the interference is maintained, and at the timing when the maintained communication channel is switched, A rule for switching the communication channel to a communication channel next to the communication channel having the interference is set as the predetermined rule.
According to the above configuration, instead of using the communication channel having the interference, the beacon transmitting terminal uses the communication channel before the communication channel having the interference again, and then uses the communication channel in the next order of the communication channel having the interference. Switch to the communication channel of. Therefore, re-synchronization with another beacon receiving terminal that failed to receive the start beacon and the end beacon can be performed early.

In order to solve the above problem, the invention according to claim 6 is configured such that each time a communication channel is switched, one of a plurality of wireless terminals is a beacon transmitting terminal in a predetermined order, and the remaining wireless terminals are a beacon receiving terminal. A beacon receiving terminal of a wireless communication system,
A communication unit that transmits and receives a start beacon, data information, and an end beacon,
A timer unit that measures a communication channel switching cycle of the communication unit,
A channel switching unit that switches the communication channel of the communication unit according to a predetermined rule in accordance with the switching cycle of the communication channel,
A determination unit that determines the presence or absence of the interference of the communication channel, and records the communication channel information of the communication channel having the interference in the interference channel skip information of the beacon receiving terminal,
Beacon analysis for analyzing the interference channel skip information included in the start beacon and the end beacon received by the communication unit and adding the communication channel information included in the interference channel skip information to the interference channel skip information of the beacon receiving terminal Part,
The timer unit terminates reception of reset information included in the start beacon in the communication unit, or resets when the channel switching unit switches the communication channel, and receives channel switching information included in the end beacon. Time the switching cycle of the communication channel up to the point where it should be completed,
The channel switching unit,
When receiving the end beacon, when the reception of the channel switching information included in the end beacon is completed, the communication channel is set based on the interference channel skip information included in the end beacon and the predetermined rule. switching,
When not receiving the end beacon, the determination unit records the communication channel information of the communication channel of the end beacon in the interference channel skip information of the beacon receiving terminal, and the timer unit switches the channel included in the end beacon. The communication channel is switched based on the interference channel skip information of the beacon receiving terminal and the predetermined rule when indicating a time point at which reception of information is to be completed.

According to the above configuration, the beacon receiving terminal can change the communication channel regularly even if a specific communication channel cannot be used due to a long interference wave. An increase in delay time can be prevented.
Further, according to the above configuration, the beacon receiving terminal can skip the communication channel that has been receiving interference by using the interference channel skip information included in the end beacon of the communication channel that does not have interference. Can be prevented.
Further, according to the above configuration, when the beacon receiving terminal cannot receive the end beacon, the communication channel of the end beacon can be skipped by adding the communication channel of the end beacon to the interference channel skip information. An increase in delay time can be prevented.
Further, according to the above configuration, even if the timing of the transmission frame is shifted within the length of the transmission frame in which the data information is transmitted, the beacon receiving terminal receives the first start beacon or the last end beacon of the transmission frame. Thus, the shifted timing can be reset. Therefore, resynchronization with the beacon transmitting terminal and other beacon receiving terminals can be achieved.

In order to solve the above problem, according to the invention according to claim 7, in the beacon receiving terminal according to claim 6, before receiving the start beacon, the communication channel may have been interfered by another wireless communication system. Nevertheless, if the start beacon does not include the interference channel skip information of the communication channel, the communication device further includes a beacon generation unit that generates an intermediate beacon including the interference channel skip information of the communication channel, A unit transmitting the intermediate beacon.
If the beacon transmitting terminal does not interfere with the same communication channel due to the installation location and the like, and the specific beacon receiving terminal receives the interference, the beacon transmitting terminal terminates including the interference channel skip information of the communication channel. Cannot send beacons. However, according to the above configuration, the beacon receiving terminal that has recognized that the interference channel skip information is not included in the start beacon transmits an intermediate beacon that includes the interference channel skip information. Can recognize the interference information of the previous communication channel and transmit the end beacon including the interference channel skip information. Therefore, the beacon transmitting terminal and the beacon receiving terminal included in the wireless communication system can skip the interference channel and continue to synchronize.

In order to solve the above problem, the invention according to claim 8 is the beacon receiving terminal according to claim 6 or 7, wherein the start beacon further includes transmission request information, and the transmission request information is activated. If the transmission request information is not activated, a priority processing period in which the beacon transmitting terminal transmits data information preferentially after transmission of the start beacon is provided. Is provided, and the beacon receiving terminal can transmit data information.
According to the above configuration, only when there is a transmission request to the beacon transmission terminal, the priority processing period is assigned, so that when there is no transmission request to the beacon transmission terminal, other wireless terminals can efficiently use the communication channel. Will be possible.

In order to solve the above problem, the invention according to claim 9 is the beacon receiving terminal according to any one of claims 6 to 8, wherein the communication unit is continuously connected to all communication channels, When the end beacon is not received, the channel switching unit waits for reception of the start beacon or the end beacon on the communication channel set first in the communication channel switching order.
If the timing of the beacon receiving terminal is out of the predetermined time or the change order of the communication frame is out of alignment, the beacon receiving terminal cannot completely synchronize with the beacon transmitting terminal and other beacon receiving terminals. May be lost. However, according to the above configuration, the beacon receiving terminal waits on the communication channel set at the beginning of the communication channel switching order, so that after a lapse of time, the beacon transmitting terminal and other beacon receiving terminals can be synchronized. Become like

In order to solve the above problem, an invention according to claim 9 is a wireless communication system, wherein the beacon transmitting terminal according to any one of claims 1 to 5, the beacon receiving terminal according to any one of claims 6 to 9, , Is included.
According to the above configuration, the beacon receiving terminal can change the communication channel regularly even if a specific communication channel cannot be used due to a long interference wave. An increase in delay time and a communication disabled state can be avoided.

  ADVANTAGE OF THE INVENTION According to this invention, while avoiding the communication channel which is a frequency band which is receiving interference autonomously, it is possible to avoid an increase in communication delay time and a communication disabled state when radio wave interference occurs for a long time.

It is an example of the wireless communication network which comprises a wireless communication system. FIG. 3 is a block diagram illustrating a configuration example of hardware of a wireless terminal. FIG. 5 is a diagram illustrating a beacon transmission timing and a communication channel switching timing in the embodiment. It is a figure showing composition of a start beacon. It is a figure showing composition of an end beacon. FIG. 3 is a diagram illustrating a configuration example of a data frame. It is an example of a transmission frame when there is a request for priority transmission. It is an example of a transmission frame when there is no request for priority transmission. 5 is a flowchart illustrating an initial operation after the wireless terminal is activated. It is the flowchart which showed the process after switching a communication channel. It is a flowchart at the time of a radio | wireless terminal operating as a beacon transmission terminal. It is a flowchart at the time of a radio | wireless terminal operating as a beacon transmission terminal. It is a flowchart at the time of a radio | wireless terminal operating as a beacon receiving terminal. It is a flowchart at the time of a radio | wireless terminal operating as a beacon receiving terminal. FIG. 3A is a diagram illustrating an example of a channel switching order when interference does not occur in a communication channel. FIG. 4B is a diagram illustrating an example of a channel switching order when interference occurs in the communication channel 2; (A) Basic frame without interference. (B) An example of interference channel skip determination criteria. (C) An example of an interference channel skip determination criterion. (D) An example of an interference channel skip determination criterion. (E) An example of interference channel skip determination criteria. (F) An example of an interference channel skip determination criterion. FIG. 4 is a schematic diagram when a beacon transmitting terminal detects interference. It is a schematic diagram when a beacon receiving terminal detects interference. It is a schematic diagram which shows resynchronization of a beacon receiving terminal by beacon reception. It is a schematic diagram which shows resynchronization of a beacon transmission terminal. It is another example of the wireless communication network which comprises a wireless communication system. 13 is a drawing for explaining Patent Document 1 as a conventional technique. 13 is a drawing for explaining Patent Document 1 as a conventional technique. 13 is a drawing for explaining Patent Document 1 as a conventional technique. 13 is a drawing for explaining Patent Document 1 as a conventional technique. 11 is a diagram for explaining Patent Document 2 which is a conventional technique. 11 is a diagram for explaining Patent Document 2 which is a conventional technique. 11 is a diagram for explaining Patent Document 2 which is a conventional technique. 13 is a drawing for explaining Patent Document 3 which is a conventional technique. 13 is a drawing for explaining Patent Document 3 which is a conventional technique. 13 is a drawing for explaining Patent Document 3 which is a conventional technique.

(Overview of wireless communication system)
In the wireless network composed of a plurality of wireless terminals according to the present embodiment, each wireless terminal performs communication by regularly switching two or more communication channels (frequency bands) to thereby perform interference in a frequency band receiving interference. Communication can be avoided independently. Each wireless terminal transmits a beacon at the beginning and end of a transmission frame in a preset beacon transmission order, and synchronizes with other wireless terminals. The channel switching cycle is determined in advance, and as soon as the switching time comes, each wireless terminal autonomously switches the frequency. In addition to switching the frequency, the wireless terminal that transmits the beacon also switches according to the beacon transmission order. Even if the synchronization signal by the beacon cannot be received, as described above, since each wireless terminal can independently switch the frequency, all wireless terminals can communicate on the same channel. Further, when interference occurs, the interference channel skip information is shared by all wireless terminals by transmitting and receiving beacons, so that all wireless terminals can communicate while avoiding the channel in which interference occurs. As a basic operation of the wireless terminal, except for data transmission, Ack (Acknowledgment) transmission, and beacon transmission operation, the wireless terminal always waits in a reception state and detects reception intensity. Further, it is determined from the detected reception strength whether the received data is data, a beacon, an Ack, or the like, or interference.

  FIG. 1 shows a configuration example of a wireless communication network constituting the wireless communication system of the present embodiment. In FIG. 1, the wireless terminals 1 to 10 form a wireless communication network. As a wireless communication system, a CSMA / CA (Carrier Sense Multiple Access / Collision Aidance) system is assumed.

  FIG. 2 illustrates an example of a hardware block diagram of the wireless terminal 200 according to the present embodiment. The beacon transmitting terminal and the beacon receiving terminal described in the claims are realized as the wireless terminal 200. The wireless terminal 200 is a general computer including a communication unit 210, a determination unit 220, a control unit 230, an I / F (interface) unit 240, and an information recording unit 250. A general computer executes the communication program to realize the functions shown in FIG. The control unit 230 is a CPU (Central Processing Unit). The control unit 230 executes processing in the wireless terminal 200 by reading and writing data stored in the information recording unit 250, and inputting and outputting data to and from the communication unit 210.

  The communication unit 210 includes a transmission / reception switching unit 211, a radio transmission unit 212, and a radio reception unit 213. When the radio terminal 200 is in the transmission mode, the transmission / reception switching unit 211 connects the antenna and the radio transmission unit 212. When the wireless terminal 200 is in the reception mode, the transmission / reception switching unit 211 connects the antenna and the wireless reception unit 213.

  The transmission / reception switching unit 211 switches the wireless terminal 200 to the transmission mode when transmitting data or a beacon, and switches the wireless terminal 200 to the reception mode otherwise.

  The wireless transmission unit 212 has a function of transmitting wireless signals such as data, a start beacon, an intermediate beacon, and an end beacon.

  The wireless reception unit 213 has a function of performing reception processing of wireless signals such as data received from another wireless terminal 200 by an antenna, a start beacon, an intermediate beacon, and an end beacon.

  Determination section 220 includes a reception strength determination section 221 and an interference determination section 222.

  The reception intensity determination unit 221 has a function of determining whether the power of the received signal has exceeded a threshold level.

  The interference determination unit 222 has a function of determining whether a received signal exceeding the threshold level is from the own wireless communication system or from another wireless communication system. If the received signal is from another wireless communication system, it is determined that interference has occurred in the current communication channel. When the interference pattern shown in FIG. 14 occurs in the communication channel, the interference determination unit 222 determines the communication channel as the interference channel, and records the communication channel information of the communication channel in the interference channel skip information. I do.

  The control unit 230 includes a beacon generation unit 231, a data generation unit 232, a beacon analysis unit 233, a channel switching unit 234, a data processing unit 235, and a timer unit 236. Then, the control unit 230 transmits and receives data to and from the I / F (interface) unit 240, transmits and receives information to and from the information recording unit 250, transmits data and beacon information to the wireless transmission unit 212, and transmits data to the wireless reception unit 213. It receives data and beacon information.

  The beacon generation unit 231 starts the beacon when the own wireless terminal 200 transmits a beacon as a beacon transmission terminal based on the beacon transmission order information, the channel switching period information, and the timer information stored in the information recording unit 250. Alternatively, it has a function of generating and transmitting an end beacon. In some cases, an intermediate beacon is generated, but conditions for generating the intermediate beacon will be described later.

  The start beacon includes interference channel skip information for skipping the communication channel when there is interference in a communication channel in the wireless communication network, transmission request information indicating the presence or absence of priority transmission processing, and time reset information. . Also, at the beginning of the start beacon, address information of the beacon transmitting terminal that transmitted the start beacon is added.

  The interference channel skip information of the start beacon includes interference channel skip information of the end beacon received on another communication channel before transmission of the start beacon and interference channel skip information recorded in the information recording unit 250 of the own wireless terminal 200. It is.

  The interference channel skip information includes, for example, bits for the number of communication channels used by the wireless communication system. Each bit and the communication channel are associated in advance, and when the bit is “1”, it indicates that the communication channel corresponding to the bit should be skipped, and when the bit is “0”, the communication channel corresponds to the bit. It indicates that the corresponding communication channel should be skipped.

  The end beacon includes interference channel skip information for skipping a communication channel in a wireless communication network when there is interference, and channel switching information indicating channel switching timing. Also, at the head of the end beacon, address information of the beacon transmitting terminal that transmitted the end beacon is added.

  The interference channel skip information of the end beacon includes the interference channel skip information of the start beacon transmitted on the communication channel of the end beacon and the interference channel skip information recorded in the information recording unit 250 of the own wireless terminal 200.

  The data generation unit 232 has a function of generating data to be transmitted when a transmission request is issued from the I / F unit 240.

  The beacon analysis unit 233 has a function of extracting the above-described various beacon information included in the start beacon or the end beacon from the received start beacon or the end beacon, and recording the extracted information in the information recording unit 250. The control unit 230 resets the timer unit based on the time reset information extracted from the start beacon, and records the time measured by the timer unit as timer information of the information recording unit 250. In addition, the beacon analysis unit 233 may set the timer information of the information recording unit 250 to an initial value such as “0” based on the time reset information.

  The channel switching unit 234 switches the communication channel at the timing when the reception of the channel switching information included in the termination beacon is terminated. If the end beacon has not been received, the timer information stored in the information recording unit 250 is read out, and the communication channel is switched when the timer information reaches the timing to end the reception of the channel switching information. When switching the communication channel, the communication channel to be changed next is specified based on the channel switching order information and the interference channel skip information stored in the information recording unit 250, and the communication channel is switched.

  The data processing unit 235 has a function of performing data processing on the received data and transmitting the data to the I / F unit 240. If the received signal is determined to be an interference signal, the data processing unit 235 records information indicating that the communication channel of the received signal has interference in the interference information of the information recording unit 250.

  The timer unit 236 counts the time from when the communication channel is switched and the timer is reset to when the transmission and reception of the channel switching information included in the end beacon ends as the channel switching period. Also, the time from receiving the time reset information included in the start beacon to the timing at which transmission and reception of the channel switching information included in the end beacon ends is counted as the channel switching period. Since the transmission frame period for transmitting and receiving data information from the start beacon to the end beacon, the transmission and reception period of the start beacon, and the transmission and reception period of the end beacon are fixed during the operation of the wireless communication system, the channel switching period is determined.

  The I / F unit 240 has an interface function with an external device. The external device can be any electronic device.

  The information recording unit 250 stores various information including timer information, interference information, channel switching cycle information, interference channel skip information, beacon transmission order information, and channel switching order information. Transmitting and receiving.

  The timer information records the elapsed time from the beginning of the channel switching period as time information in real time, based on the time measured by the timer unit 236, using a predetermined channel switching period as a unit. In addition, when the time reset information is extracted from the received start beacon, the time information is reset and synchronized with another wireless terminal 200. Further, even after switching the channel, the time information is reset to synchronize with another wireless terminal 200 (see FIG. 10). All wireless terminals 200 keep time in units of the predetermined channel switching period, and automatically change communication channels at the channel switching period.

  In the interference information, information of a communication channel determined to have interference by the interference determination unit 222 is recorded. In addition, interference information in the wireless communication network analyzed by the beacon analyzer 233 is also recorded. For example, bits corresponding to the number of communication channels used in the wireless communication system are prepared in advance, and the order of the bits is made to correspond to the communication channel. If interference occurs in the communication channel, the control unit 230 sets the corresponding bit to “1”. Set. If no interference has occurred in the communication channel, control section 230 sets the corresponding bit to “0”.

  In the channel switching cycle information, information indicating a switching cycle of a plurality of communication channels defined in advance is recorded. That is, the time from the timing at which the transmission / reception of the time reset information of the start beacon is completed or the timing at which the switching of the communication channel is completed to the timing at which the transmission / reception of the channel switching information included at the end of the end beacon is completed is recorded. I have.

  The interference channel skip information records and updates the interference channel skipped by the control unit 230 from the accumulated interference information. When the end beacon is received or when the channel switching timing comes due to the timer information, the control unit 230 transmits the interference channel skip information to the channel switching unit 234.

  In the channel switching order information, a switching order of a plurality of communication channels defined in advance is recorded. That is, when no interference occurs in the communication channel, the wireless terminal 200 switches the communication channel in the channel switching order. For example, as shown in FIG. 13A, the channel switching order is set so that all communication channels prepared in one cycle are used once. When one cycle of the channel switching order ends, the wireless terminal 200 selects a communication channel again from the head of the channel switching order.

  The beacon transmission order information records the order in which the wireless terminal 200 becomes the beacon transmission terminal. For example, if the identification information of the wireless terminals 200 is sequentially recorded in the beacon transmission order information, the wireless terminal 200 can recognize which wireless terminal 200 will be the beacon transmission terminal every time the communication channel is switched. All wireless terminals 200 included in the wireless communication system become beacon transmitting terminals in turn. When one cycle of the beacon transmission order ends, the wireless terminal 200 to be the beacon transmission terminal is determined again from the beginning of the beacon transmission order.

  FIG. 3 is a diagram schematically illustrating a transmission cycle of a start beacon and an end beacon and a channel switching cycle.

  First, as a beacon transmitting terminal, the wireless terminal 1 transmits a start beacon on CH (Channel: Channel) 1, which is an initial communication channel arranged at the head of channel switching order information, and transmits an end beacon after Tms. At this time, the wireless terminals 2 to 10 receive the start beacon and the end beacon on CH1 as beacon receiving terminals. Tms is a transmission frame period which is a transmission / reception period of data information, and is a fixed period while the wireless communication system is operating.

  After the wireless terminal 1 transmits the end beacon, all wireless terminals switch to CH2, and the wireless terminal 2 that is the next wireless terminal after the wireless terminal 1 becomes a beacon transmitting terminal and transmits a start beacon. Hereinafter, similarly, transmission and reception of the start beacon and the end beacon and switching of the communication channel are repeated.

  In FIG. 3, a start beacon and an end beacon are transmitted in a Tms cycle. The communication channel is changed at the timing when the transmission and reception of the end beacon is completed, and the start beacon is transmitted after the communication channel is switched. As described above, the cycle time T is a transmission frame period, and is defined in advance in the wireless communication system. Also, the wireless communication system cannot change the specified period time T while the wireless terminal is operating.

  Further, in FIG. 3, ten wireless terminals from the wireless terminal 1 to the wireless terminal 10 are used, and the number of wireless terminals does not change during the operation of the wireless terminals. That is, the wireless terminal is basically a fixed station, and does not consider a mobile station. Therefore, the increase or decrease in the number of wireless terminals in the wireless communication network is not considered, and the wireless terminals to be assigned as the wireless terminals 10 from the wireless terminal 1 must be defined first. All wireless terminals in the wireless communication system become beacon transmitting terminals in turn.

  However, when the wireless terminal is not operating, the wireless communication system can add a new wireless terminal or reduce the number of wireless terminals. For example, when the wireless communication system adds one new wireless terminal, the wireless communication system assigns the newly added wireless terminal as the wireless terminal 11 in the next order of the wireless terminal 10 and the beacon of all wireless terminals. Information such as transmission order information is also updated.

  FIG. 3 shows a basic communication channel switching cycle. With the initial channel set to CH1, all terminals simultaneously switch in the order of CH1, CH2, and CH3 in a cycle obtained by adding the transmission and reception periods of the start beacon and the end beacon to Tms. In addition, the beacon transmitting terminal that transmits the beacon also switches from the wireless terminal 1 to the wireless terminal 10 in order at a period obtained by adding the transmission and reception periods of the start beacon and the end beacon to Tms.

  In this case, it is desirable that all wireless terminals can be synchronized by beacons. However, even when the beacon cannot be received, the communication channel is automatically switched at an interval obtained by adding the transmission and reception periods of the start beacon and the end beacon to Tms, so that it is possible to synchronize the wireless terminals.

  That is, if the beacon receiving terminal can receive the end beacon, the beacon receiving terminal switches the communication channel when the reception of the channel switching information of the end beacon is completed. When the end beacon has not been received, the communication channel is switched based on the timer information of the information recording unit 250.

  FIG. 4 shows a configuration diagram of the start beacon. The start beacon includes a source address, interference channel (CH) skip information, source transmission request information, and time reset information. The start beacon is transmitted at the beginning of a transmission frame period during which the wireless terminal 200 as a beacon transmitting terminal that transmits a beacon transmits and receives data.

  The source address is the address of the wireless terminal 200 that transmitted the start beacon. The interference channel (CH) skip information is interference channel skip information when the control unit 230 determines to skip the interference channel based on the interference state of the communication channel in the wireless communication network. All wireless terminals 200 perform an interference channel skip operation according to the interference channel (CH) skip information.

  The transmission request information is information indicating whether or not there is a data transmission request to the beacon transmitting terminal that transmitted the beacon. If there is a transmission request, the transmission request information is in the active state, and priority transmission processing and priority reception processing, which will be described in detail later, are executed. For example, the transmission request information is represented by one bit. When there is a transmission request, the bit is set to “1” to indicate an active state, and when there is no transmission request, the bit is set to “0” and the inactive state is set. Is shown.

  The time reset information is information for all the wireless terminals 200 to reset the time at the same time so that all the wireless terminals 200 synchronize. If there is a deviation in the synchronization between the wireless terminals 200, resynchronization between the wireless terminals 200 is enabled by the time reset information.

  That is, the beacon receiving terminal that has received the time reset information resets the timer unit 236 and sets the timer information of the information recording unit 250 to an initial value, for example, “0”.

  FIG. 5 shows a configuration diagram of the end beacon. The end beacon includes a source address, interference channel (CH) skip information, and channel (CH) switching information. The end beacon is transmitted by the beacon transmitting terminal after the end of the transmission frame.

  The transmission source address is the address of the wireless terminal 200 as the beacon transmitting terminal that transmitted the end beacon. The interference channel (CH) skip information is the interference channel skip information when it is determined that the interference channel is skipped based on the interference state in the wireless communication network. All wireless terminals 200 perform an interference channel skip operation according to the interference channel (CH) skip information.

  The channel (CH) switching information is channel switching start information for switching to the next communication channel. At the timing when transmission and reception of the channel (CH) switching information are completed, all wireless terminals 200 simultaneously switch the communication channel to the next communication channel. Switch.

  When there is a deviation in the synchronization between the wireless terminals 200, resynchronization between the wireless terminals 200 is enabled by the channel (CH) switching information. That is, if the beacon receiving terminal can receive the end beacon, it switches the communication channel at the reception completion timing of the channel (CH) switching information of the end beacon, so that the start timing of the communication channel is synchronized. Further, at the timing when the communication channel is switched, the timer unit 236 is reset.

  FIG. 6 shows a configuration example of a data frame. At the beginning of the data frame, there is a bit synchronization signal for synchronizing in bit units, followed by a frame synchronization signal for synchronizing in frame units, and then an ID unique to the wireless communication system. There is a header that contains Following the header, there is a payload that is the main body of data, and finally, there is an error detection and correction code for detecting and correcting data errors.

  As shown in FIG. 6, since the data frame includes an ID unique to the wireless communication system, whether the wireless signal received by wireless terminal 200 is a wireless signal of the wireless communication system is determined by identifying the unique ID. It can be determined based on whether or not reception was successful.

  FIG. 7 shows a transmission frame when a transmission request is issued to the wireless terminal X that is the beacon transmitting terminal that has transmitted the beacon. When there is a transmission request for transmitting data to the wireless terminal X, the wireless terminal X includes information indicating that there is a transmission request in the transmission request information of the transmission source in the start beacon, and transmits the start beacon. . For example, as described above, the transmission request information may be a 1-bit signal. If the transmission request bit is “1”, there is a transmission request, and if the transmission request bit is “0”, the transmission request is transmitted. It can indicate that there is no request.

  After the start beacon is transmitted, the wireless terminal X is given a data transmission priority, so that data can be transmitted preferentially. After the completion of the priority data transmission, all terminals can make a transmission request in a transmission frame using CSMA / CA or the like.

  FIG. 8 shows a transmission frame when there is no transmission request to the wireless terminal X. If there is no transmission request to the wireless terminal X, after transmitting the start beacon, all terminals are given a transmission right, and all terminals make transmission requests by CSMA / CA or the like.

  FIG. 9 is a flowchart illustrating an initial operation when the wireless terminal 200 is activated.

  In step S901, when the wireless terminals 200 are activated, each wireless terminal 200 sets a communication channel to an initial channel predetermined in the wireless communication system. This is performed by each wireless terminal 200 referring to the channel switching order information of the information recording unit 250 and setting the first communication channel of the channel switching order information as the initial channel. Next, the wireless terminal 200 proceeds to step S902.

  In step S902, it is determined whether or not the wireless terminal 200 is the initial wireless terminal 200 in the preset beacon transmission order. Since the beacon transmission order information is stored in the information recording unit 250, the wireless terminal 200 recognizes the identification information of the first wireless terminal 200 in the beacon transmission order information, and determines whether the wireless terminal 200 is the initial wireless terminal 200. Can be determined. When the wireless terminal 200 is the initial wireless terminal 200 (step S902: YES), the wireless terminal 200 proceeds to step S903, and when it is not the initial wireless terminal 200 (step S902: NO), the process proceeds to step S910.

  In step S903, before the beacon transmitting terminal that is the initial wireless terminal 200 transmits the start beacon, the reception intensity determination unit 221 determines whether the reception intensity is detected. If the reception intensity is detected (step S903: YES), the initial radio terminal 200 proceeds to step S904, and if the reception intensity is not detected (step S903: NO), the process proceeds to step S905.

  In step S904, if the reception strength is detected, the initial wireless terminal 200 cannot transmit the start beacon. Therefore, the initial wireless terminal 200 proceeds to step S903 again to wait on the initial channel until the reception strength is no longer detected. During the period in which the initial wireless terminal 200 communicates, the other wireless terminals 200 are not to communicate. Therefore, if the reception strength is detected, the initial radio terminal 200 can determine that the received signal is a radio signal from another radio communication system and that interference has occurred in the communication channel.

  In step S905, since the reception strength has not been detected, the initial wireless terminal 200 transmits a start beacon, and proceeds to step S906.

  In step S906, the initial wireless terminal 200 waits until a transmission frame period, which is a preset specified time, elapses, and then proceeds to step S907.

  In step S907, before the initial wireless terminal 200 transmits the end beacon, the reception intensity determination unit 221 determines whether the reception intensity is detected. If the reception intensity is detected (step S907: YES), the initial wireless terminal 200 proceeds to step S909, and if the reception intensity is not detected (step S907: NO), the process proceeds to step S908.

  In step S908, since the reception strength has not been detected, the initial wireless terminal 200 includes the necessary information in the end beacon and transmits the end beacon. Then, the channel switching unit 234 performs a process of switching the communication channel to the next channel based on the channel switching order information.

  If the reception strength is detected in step S909, the initial wireless terminal 200 cannot transmit the end beacon, so that the interference channel skip information records that there is interference in the initial channel. Then, the channel switching unit 234 performs communication based on the interference channel skip information and the channel switching order information at the end of the communication channel switching period from the timing of starting transmission of the start beacon to the timing of completing transmission of the end beacon. Switch channels.

  In step S910, since the initial wireless terminal 200 is a beacon receiving terminal, it waits in a receiving state and determines whether a beacon has been received. If the initial wireless terminal 200 has received a beacon (step S910: YES), the initial wireless terminal 200 proceeds to step S912, and if not (step S910: NO), proceeds to step S911.

  In step S911, the initial wireless terminal 200 that is the beacon receiving terminal proceeds to step S910 to wait on the initial channel until receiving a beacon.

  In step S912, the initial wireless terminal 200 that has received the beacon analyzes whether the received beacon is a start beacon. If the received beacon is a start beacon (step S912: YES), the initial wireless terminal 200 proceeds to step S913. If the received beacon is not the start beacon (step S912: NO), the received beacon is the end beacon, so the channel switching unit 234 of the initial wireless terminal 200 switches the communication channel to the next channel and ends the process. I do. The start beacon and the end beacon include beacon identification information.

  In step S913, since the received beacon is the start beacon, the initial wireless terminal 200 resets the timer unit 236 based on the start beacon time reset information, and waits in the reception state until the transmission frame period ends. Next, the initial wireless terminal 200 proceeds to step S914.

  In step S914, the initial wireless terminal 200 determines whether an end beacon has been received. If the initial wireless terminal 200 does not receive the end beacon (step S914: NO), the initial wireless terminal 200 proceeds to step S915. If the initial wireless terminal 200 receives the end beacon (step S914: YES), the communication channel is changed to the next. Switch to the channel and end the process. That is, when the reception of the channel switching information of the end beacon is completed, the communication channel is switched to the next channel based on the channel switching order information, and the process ends.

  Since step S915 is a case where the initial wireless terminal 200 has not received the end beacon, the initial wireless terminal 200 determines that there is interference in the communication channel, updates the interference channel skip information, switches the communication channel to the next channel, and performs processing. To end.

  That is, when timer section 236 indicates a point in time at which reception of the channel switching information included in the end beacon should be completed, initial radio terminal 200 switches the communication channel based on the interference channel skip information and the channel switching order information.

  The above operation is the initial operation when the wireless terminal 200 is activated, and the specified time, which is the transmission frame period, has elapsed. At the time of the initial operation, transmission operations other than the beacon are not performed.

  FIG. 10 is a flowchart showing the processing after switching the communication channel. The communication channel to which the wireless terminal 200 switches can be determined by referring to the channel switching order information of the information recording unit 250.

  In step S1001, the wireless terminal 200 resets the timer unit 236, sets the timer information of the information recording unit 250 to an initial value, and proceeds to step S1002.

  In step S1002, it is determined whether or not the order in which the wireless terminals 200 transmit beacons has come. When the order in which the wireless terminals 200 transmit beacons has come (step S1002: YES), the process proceeds to process A, and when it is not in the order to transmit beacons (step S1002: NO), the process proceeds to process B. . Whether or not the order in which the wireless terminals 200 transmit beacons can be determined by referring to the beacon transmission order information of the information recording unit 250.

  11A and 11B show a flowchart of the process A. Process A is a process flow when the wireless terminal 200 transmits a beacon and functions as a beacon transmitting terminal.

  In step S1101, before the wireless terminal 200 transmits the start beacon, it is determined whether or not the reception intensity is detected by the reception intensity determination unit 221. When the reception intensity is detected (step S1101: YES), the process proceeds to step S1107, and when the reception intensity is not detected (step S1101: NO), the process proceeds to step S1102.

  In step S1102, since the reception strength has not been detected, the wireless terminal 200 transmits a start beacon, and proceeds to step S1103. In this case, the interference channel skip information recorded in the information recording unit 250 and the interference channel skip information of the end beacon received immediately before are transmitted as the interference channel skip information of the start beacon.

  In step S1103, if the wireless terminal 200 that transmitted the start beacon in step S1102 has set the transmission request information included in the start beacon to a transmission request (step S1103: YES), the process proceeds to step S1104. If the wireless terminal 200 has set the transmission request information included in the start beacon to no transmission request (step S1103: NO), the process proceeds to step S1108 and skips the priority transmission process.

  In step S1104, before the wireless terminal 200 performs priority transmission, it is determined whether or not the reception strength determination unit 221 detects the reception strength. When the reception intensity is detected (step S1104: YES), the wireless terminal 200 proceeds to step S1116, and when the reception intensity is not detected (step S1104: NO), the process proceeds to step S1105.

  In step S1105, the wireless terminal 200 preferentially transmits the data information, and proceeds to step S1106.

  In step S1106, wireless terminal 200 determines whether or not an Ack signal for the preferentially transmitted data information has been received. If wireless terminal 200 has received the Ack signal (step S1106: YES), wireless terminal 200 proceeds to step S1108, and if it has not received the Ack signal (step S1106: NO), proceeds to step S1115. The priority transmission processing ends in step S1106.

  In step S1107, the wireless terminal 200 updates the interference information, and proceeds to step S1108. That is, since interference occurs in the communication channel and the wireless terminal 200 cannot transmit the start beacon, the wireless terminal 200 records information indicating that interference has occurred in the communication channel in the interference information of the information recording unit 250.

  In step S1108, since the wireless terminal 200 is in the reception mode, the reception intensity determination unit 221 determines whether the reception intensity is detected. If the reception intensity is detected (step S1108: YES), the wireless terminal 200 proceeds to step S1109. If the reception intensity is not detected (step S1108: NO), the process proceeds to step S1113.

  In step S1109, since the reception strength has been detected, the wireless terminal 200 determines whether an ID unique to the wireless communication system is detected from the received signal. If the unique ID is detected (step S1109: YES), the wireless terminal 200 proceeds to step S1110, and if the unique ID is not detected (step S1109: NO), the process proceeds to step S1116.

  In step S1110, wireless terminal 200 determines whether data information has been successfully received from the received signal. If the wireless terminal 200 has successfully received the data information (step S1110: YES), the wireless terminal 200 proceeds to step S1111. If the wireless terminal 200 has not been able to receive the data information normally (step S1110: NO), the process proceeds to step S1116. Proceed to.

  In step S1111, the wireless communication determines whether the data received in step S1110 is an intermediate beacon. If the received data is an intermediate beacon (step S1111: YES), wireless terminal 200 proceeds to step S1116, and if the received data is not an intermediate beacon (step S1111: NO), the process proceeds to step S1112.

  Since step S1112 is a case where the wireless terminal 200 has successfully received the data information, the wireless terminal 200 transmits an Ack signal to the wireless terminal 200 that transmitted the data information, and proceeds to step S1117.

  Step S1113 is a case in which the reception intensity based on the received signal is not detected even though the wireless terminal 200 is in the reception mode. Therefore, it is determined whether the wireless terminal 200 has a data information transmission request. If there is a data information transmission request (step S1113: YES), the wireless terminal 200 proceeds to step S1114. If there is no data information transmission request (step S1113: NO), the wireless terminal 200 proceeds to step S1117. move on.

  Step S1114 is a state where there is data information to be transmitted to the wireless terminal 200, so the wireless terminal 200 transmits the data information, and proceeds to step S1115.

  In step S1115, wireless terminal 200 determines whether or not an Ack signal for the transmitted data information has been received. If the wireless terminal 200 has received the Ack signal (step S1115: YES), the wireless terminal 200 proceeds to step S1117, and if not received (step S1115: NO), proceeds to step S1116.

In step S1116, the wireless terminal 200 determines that the interference information of the communication channel in which the interference occurred has interference, updates the interference information, and proceeds to step S1117. When the interference information corresponds to the interference patterns 1401 to 1405 in FIG. 14, a communication channel corresponding to the interference channel skip information is recorded in order to skip the corresponding communication channel.
When the intermediate beacon is received, the communication channel included in the interference channel skip information of the intermediate beacon is recorded in addition to the interference channel skip information of the information recording unit 250.

  In step S1117, the wireless terminal 200 checks the elapsed time. That is, the wireless terminal 200 checks whether or not a specified time, which is a data frame period in which data information can be transmitted and received, has elapsed since the transmission of the start beacon. If the specified time has expired (step S1117: YES), the wireless terminal 200 proceeds to step S1118. If the specified time has not ended (step S1117: NO), the wireless terminal 200 transmits and receives data information. The process advances to step S1108 to perform the process.

  In step S1118, wireless terminal 200 determines whether reception strength is detected by reception strength determination section 221 or not. If the reception intensity is detected (step S1118: YES), the wireless terminal 200 proceeds to step S1120, and if the reception intensity is not detected (step S1118: NO), the process proceeds to step S1119.

  In step S1119, since there is no interference in the communication channel, the wireless terminal 200 transmits an end beacon, and then performs a channel change process.

  In step S1120, the wireless terminal 200 determines that the interference information of the channel in which the interference occurred has interference, updates the interference information, and then performs a channel change process. In this case, since the wireless terminal 200 cannot transmit the end beacon, it corresponds to the interference pattern 1401 in FIG. Therefore, the wireless terminal 200 records the communication channel corresponding to the interference channel skip information in order to skip the corresponding communication channel. The above is the processing flow of the processing A.

  12A and 12B show a flowchart of the process B. Process B is a process flow when the wireless terminal 200 functions as a beacon receiving terminal.

  Since step S1201 is immediately after the wireless terminal 200 switches the channel, the wireless terminal 200 determines whether a start beacon has been received from the beacon transmitting terminal. If the wireless terminal 200 has received the start beacon (step S1201: YES), the wireless terminal 200 proceeds to step S1202, and if not received (step S1201: NO), proceeds to step S1208.

  In step S1202, the wireless terminal 200 analyzes the interference channel skip information included in the start beacon, and updates the interference channel skip information in the information recording unit 250 when there is a communication channel that is interfering, and proceeds to step S1203. .

  In step S1203, the wireless terminal 200 analyzes whether the transmission request information of the start beacon is active. If the transmission request is active (step S1203: YES), the wireless terminal 200 proceeds to step S1204, and if the transmission request is not active (step S1203: NO), the process proceeds to step S1209. The state in which the transmission request is active is a state in which there is data information to be transmitted to the wireless terminal 200 that has transmitted the start beacon, and the wireless terminal 200 is requesting priority transmission processing.

  In step S1204, wireless terminal 200 waits for reception of the data information, and determines whether or not reception intensity is detected by reception intensity determination section 221. When the reception intensity is detected (step S1204: YES), the wireless terminal 200 proceeds to step S1205, and when the reception intensity is not detected (step S1204: NO), the process proceeds to step S1217.

  In step S1205, wireless terminal 200 determines whether or not an ID unique to the wireless communication system is detected from the received signal. When a unique ID is detected (step S1205: YES), the wireless terminal 200 proceeds to step S1206, and when a unique ID is not detected (step S1205: NO), the process proceeds to step S1217.

  In step S1206, wireless terminal 200 determines whether or not the data information has been successfully received. If the wireless terminal 200 has successfully received the data information (step S1206: YES), the wireless terminal 200 proceeds to step S1207. If the wireless terminal 200 has not been able to receive the data information normally (step S1206: NO), step S1217 is performed. Proceed to.

  In step S1207, since the wireless terminal 200 has successfully received the data information, the wireless terminal 200 transmits an Ack signal to the wireless terminal 200 that transmitted the data information, and proceeds to step S1221.

  In step S1208, since the wireless terminal 200 could not receive the start beacon, the wireless terminal 200 records information indicating that the current communication channel has interference in the interference information, and proceeds to step S1209.

  In step S1209, the wireless terminal 200 enters the reception mode, and the reception intensity determination unit 221 determines whether the reception intensity is detected. When the reception intensity is detected (step S1209: YES), the process proceeds to step S1210, and when the reception intensity is not detected (step S1209: NO), the process proceeds to step S1214.

  In step S1210, since the reception intensity has been detected, wireless terminal 200 determines whether or not an ID unique to the wireless communication system is detected from the received signal. If a unique ID is detected (step S1210: YES), the wireless terminal 200 proceeds to step S1211, and if a unique ID is not detected (step S1210: NO), the process proceeds to step S1217.

  In step S1211, the wireless terminal 200 determines whether the data information has been successfully received. If the wireless terminal 200 has successfully received the data information (step S1211: YES), the wireless terminal 200 proceeds to step S1212. If the wireless terminal 200 has not been able to normally receive the data information (step S1211: NO), step S1217. Proceed to.

  In step S1212, the wireless terminal 200 determines whether the wireless signal received in step S1211 is an intermediate beacon. If the received wireless signal is an intermediate beacon (step S1212: YES), the wireless terminal 200 proceeds to step S1217. If the received wireless signal is not an intermediate beacon (step S1212: NO), the wireless terminal 200 proceeds to step S1213. move on.

  In step S1213, since the wireless terminal 200 has successfully received the data information, the wireless terminal 200 transmits an Ack signal to the wireless terminal 200 that has transmitted the data information, and proceeds to step S1221.

  Step S1214 is a case where the reception intensity has not been detected, and thus it is determined whether or not the wireless terminal 200 has a request for transmitting data information. If there is a data information transmission request (step S1214: YES), the wireless terminal 200 proceeds to step S1215. If there is no data information transmission request (step S1214: NO), the wireless terminal 200 proceeds to step S1218.

  In step S1215, since there is data information to be transmitted to the wireless terminal 200, the wireless terminal 200 transmits data information, and proceeds to step S1216.

  In step S1216, wireless terminal 200 determines whether or not an Ack signal for the transmitted data information has been received. If wireless terminal 200 has received the Ack signal (step S1216: YES), wireless terminal 200 proceeds to step S1221, and if not received (step S1216: NO), proceeds to step S1217.

  In step S1217, the wireless terminal 200 determines that there is interference in the interference information of the communication channel in which interference has occurred, updates the interference information, and proceeds to step S1221. When the interference information corresponds to the interference patterns 1401 to 1405 in FIG. 14, a communication channel corresponding to the interference channel skip information of the information recording unit 250 is recorded in order to skip the corresponding communication channel. When the intermediate beacon is received, the communication channel included in the interference channel skip information of the intermediate beacon is recorded in addition to the interference channel skip information of the information recording unit 250.

  In step S1218, wireless terminal 200 determines whether there is a transmission request for an intermediate beacon. That is, even though interference has occurred in the wireless terminal 200 on the communication channel before receiving the start beacon, there is a case where there is no information on the communication channel in the interference channel skip information of the received start beacon. In this case, a transmission request of the intermediate beacon is generated. If there is an intermediate beacon transmission request (step S1218: YES), the wireless terminal 200 proceeds to step S1219. If there is no intermediate beacon transmission request (step S1218: NO), the wireless terminal 200 proceeds to step S1221.

  In step S1219, the wireless terminal 200 determines whether it is time to transmit an intermediate beacon. The timing at which the intermediate beacon can be transmitted is determined in advance in the wireless communication system, and the wireless communication system can set an arbitrary section of the transmission frame as a transmission / reception period of the intermediate beacon. If the current timing is a timing at which an intermediate beacon can be transmitted (step S1219: YES), the wireless terminal 200 proceeds to step S1220. If the current timing cannot transmit an intermediate beacon (step S1219: NO), the wireless terminal 200 proceeds to step S1221. .

  In step S1220, the wireless terminal 200 transmits an intermediate beacon, and proceeds to step S1221. The intermediate beacon includes information on the communication channel that is being interfered, which is not included in the interference channel skip information of the received start beacon.

  In step S1221, the wireless terminal 200 checks the elapsed time. That is, the wireless terminal 200 checks whether or not the specified time, which is the transmission frame period, has elapsed from the reception of the start beacon or the time at which the start beacon should have been received. If the specified time has elapsed (step S1221: YES), the wireless terminal 200 proceeds to step S1222. If the specified time has not ended (step S1221: NO), the wireless terminal 200 transmits and receives data information. The process advances to step S1209 to perform.

  In step S1222, wireless terminal 200 determines whether an end beacon has been received. If an end beacon has been received (step S1222: YES), the wireless terminal 200 proceeds to step S1223. If an end beacon has not been received (step S1222: NO), the wireless terminal 200 proceeds to step S1224.

  In step S1223, the wireless terminal 200 analyzes the interference channel skip information included in the end beacon, and adds the communication channel to be skipped included in the interference channel skip information of the end beacon to the interference channel skip information of the information recording unit 250. Next, a channel change process is performed.

  That is, since the wireless terminal 200 receives the end beacon, when the reception of the channel switching information included in the end beacon is completed, the wireless terminal 200 performs the communication based on the interference channel skip information and the channel switching order information included in the end beacon. Switch channels.

  In step S1224, the wireless terminal 200 performs an update to record the communication channel information of the communication channel in which the interference has occurred in the interference channel skip information, and then performs a channel change process. In this case, since the wireless terminal 200 cannot receive the end beacon, the wireless terminal 200 corresponds to the interference pattern 1401 in FIG. Therefore, the wireless terminal 200 records the communication channel corresponding to the interference channel skip information in order to skip the corresponding communication channel. Then, the communication channel is changed.

  That is, since the end beacon could not be received, the determination unit 220 records the communication channel information of the communication channel of the end beacon in the interference channel skip information of the beacon receiving terminal. Then, when the timer unit 236 indicates a point in time at which the reception of the channel switching information included in the end beacon should be completed, the timer unit 236 switches the communication channel based on the interference channel skip information and the channel switching order information of the beacon receiving terminal. The above is the processing flow of the processing B.

(Overview of channel switching order)
Next, an outline of the channel switching order will be described with reference to FIG.

  FIG. 13 is a diagram showing the switching order indicated by the channel switching order information. FIG. 13A shows the basic order, in which the channels are switched in the order of CH1 → CH2 → CH3. The number of channels may be any number as long as it is two or more. Further, the channel switching order only needs to be uniformly defined for all wireless terminals 200, and the channel switching order can be arbitrarily set by the wireless communication system. Similarly, the initial channel only needs to be uniformly defined for all wireless terminals 200, and any channel may be the initial channel. The channel switching order is stored in the information recording unit 250 as channel switching order information.

  FIG. 13B shows a channel switching order when CH2 is interfered. When CH2 is interfered, the next switching to CH2 is skipped, and switching from CH1 to CH3 is performed. Similarly, when another communication channel is interfered, the next switching operation to that communication channel is skipped, and the next communication channel that has been interfered is switched. When two communication channels interfere at the same time, switching to the two communication channels in which the interference has occurred is skipped. The communication channel to be skipped is transmitted to the other wireless terminals 200 using the interference channel skip information of the start beacon, the intermediate beacon, and the end beacon, is recorded in the interference channel skip information of the information recording unit 250, and is shared between the wireless terminals 200. Is done.

  In FIG. 13B, the interfered channel is skipped only once, but may be skipped two or more times continuously. However, the number of skips needs to be defined in advance in the wireless communication system. Each wireless terminal 200 is set to wait until a beacon can be received on the initial channel when beacons cannot be continuously received on all channels. Therefore, even if the synchronization between the wireless terminals 200 cannot be completely achieved, the synchronization can be achieved again by waiting on the initial channel. In addition, when the skip of the interfered communication channel ends, the information of the communication channel of the interference channel skip information is cleared.

  These interference communication channel skipping methods are shared among all wireless terminals 200 as a predetermined rule. Further, another skip method may be shared among all wireless terminals 200 as a predetermined rule.

(Interference channel skip determination criteria)
Next, the skip channel criterion of the interference channel will be described with reference to FIG.

  Each wireless terminal is always in a reception state except for the transmission operation, and each wireless terminal detects the reception intensity. If the reception strength exceeds the threshold value, it is determined whether the received wireless signal is from the network of the own wireless communication system or from another wireless communication system. If the received wireless signal is from another wireless communication system, it indicates that interference has occurred. Also, when the beacon transmitting terminal detects the reception strength in the start beacon transmission period and the start beacon transmission period, it also indicates that interference has occurred in the communication channel. The wireless terminal determines whether or not to perform a skip operation on the interference channel depending on the situation in which wireless interference is occurring.

FIG. 14 shows an interference pattern of the interference channel skip determination criterion.
FIG. 14A shows a basic frame, in which no interference occurs. In the basic frame of FIG. 14A, after transmitting and receiving the start beacon, each wireless terminal performs standby or communication on the same channel for Tms, then transmits and receives the end beacon, and switches the channel to the next channel. .

  FIGS. 14B to 14F show interference patterns for determining whether to skip an interference channel.

  FIG. 14B shows an interference pattern 1401. If the end beacon cannot be transmitted / received, the length of the interference is not known. Therefore, the wireless terminal determines that there is interference in the communication channel on which the end beacon could not be transmitted / received. The communication channel is recorded in the skip information.

  For example, as interference channel skip information, bits for the number of communication channels used in the wireless communication system are prepared in advance, and if interference occurs in the communication channel, the control unit 230 sets the corresponding bit to “1”. If no interference has occurred in the communication channel, control section 230 sets the corresponding bit to “0”. The communication channel and the order of the bits are determined in advance by the wireless communication system. As an example, the communication channel to be skipped can be recognized by associating the order of the communication channel of the channel switching information from the most significant bit or the least significant bit of the interference channel skip information bit.

  FIG. 14C shows an interference pattern 1402. The wireless communication system defines the interference length of the interference determination standard as Ims in advance. If the length of the interference tms is longer than the specified Ims (t> I), the wireless terminal determines that there is interference in the communication channel, and the interference is skipped by the interference channel skip information of the information recording unit 250. Record that there is.

  FIG. 14D shows an interference pattern 1403. The interference pattern 1403 indicates a case where the wireless terminal failed to transmit data information and was unable to retransmit, or a case where data transmission was possible but an Ack signal was not received. In this case, the wireless terminal determines that there is interference in the channel, and records that there is interference in the communication channel in the interference channel skip information of the information recording unit 250.

  FIG. 14E shows an interference pattern 1404. The interference pattern 1404 is a case where the wireless terminal has failed to receive data information, or has succeeded in receiving data information but failed to transmit an Ack signal. In this case, the wireless terminal determines that there is interference in the channel, and records that there is interference in the communication channel in the interference channel skip information of the information recording unit 250.

  FIG. 14F shows an interference pattern 1405. Even if the length of the interference is shorter than Ims indicated by the interference pattern 1402 in FIG. 14C (t <I), if the specified number of interferences or more is confirmed, the communication channel has no interference. The wireless terminal determines that there is, and records that interference exists in the communication channel in the interference channel skip information of the information recording unit 250. Then, based on the interference channel skip information, the interference channel is skipped at the next channel switching timing. If interference is confirmed at a rate equal to or greater than the rate specified for the transmission frame, the wireless terminal determines that there is interference in the communication channel, and updates the interference channel skip information of the information recording unit 250. The wireless communication system determines the specified number and the ratio in advance to arbitrary values.

(Transmission and reception timing of interference information)
Next, the transmission / reception timing of the interference information will be described.
Since it is conceivable that the state of occurrence of interference is different for each wireless terminal, there is a possibility that the channel switching procedure may not match between wireless terminals. Therefore, the transmission and reception timing of interference information when interference is confirmed will be described below.

  FIG. 15 illustrates a case where the wireless terminal 2 that is the beacon transmitting terminal detects the interference. Since the wireless terminal 2 which is the beacon transmitting terminal is receiving interference on CH2, the wireless terminal 2 cannot transmit the start beacon and the end beacon on CH2. Therefore, wireless terminals other than the wireless terminal 2 cannot receive the start beacon and the end beacon. As a result, wireless terminals other than the wireless terminal 2 cannot receive the start beacon and the end beacon, and thus determine that there is interference on CH2.

  In such a case, the wireless terminal 3 that is the next beacon transmitting wireless terminal and the beacon transmitting wireless terminal 4 that is next to the wireless terminal 3 perform interference channel skip including information indicating that interference has occurred on CH2. Information is transmitted by start and end beacons. All wireless terminals that have received the beacon can share the skip information of CH2. The wireless terminals skip CH2 at the timing when the channel is switched from CH1 to CH2, and switch from CH1 to CH3 next to CH2. Even when a wireless terminal other than the wireless terminal 2 receives interference at CH2 at the same timing, each wireless terminal determines CH2 from the interference channel skip information included in the beacon transmitted at the timing of performing communication with CH3 and CH1. Information to be skipped can be received. As described above, basically, the channel skip processing is performed according to the information included in the start beacon and the end beacon.

  FIG. 16 shows a case where a wireless terminal that is a beacon receiving wireless terminal detects interference from another wireless communication system.

  In FIG. 16, the wireless terminals 6, 9 and 10 which are beacon receiving wireless terminals are receiving interference on CH2. However, the wireless terminal 2 that is a beacon transmitting wireless terminal can transmit a beacon because it is not receiving interference on CH2. Also, since other wireless terminals are not receiving interference on CH2, they can receive beacons.

  Therefore, in this case, the wireless terminals other than the wireless terminal 6, the wireless terminal 9, and the wireless terminal 10 cannot recognize that the wireless terminal 6, the wireless terminal 9, and the wireless terminal 10 are receiving interference on CH2. . For this reason, if this situation continues, each wireless terminal cannot skip CH2.

  In addition, since the wireless terminal 6, the wireless terminal 9, and the wireless terminal 10 cannot receive the beacon, they cannot recognize the interference information of other wireless terminals.

  However, when the wireless terminals 6, 9, and 10 receive the start beacon of the wireless terminal 3 after switching to CH3, the start beacon of the wireless terminal 3 does not include interference channel skip information indicating that CH2 is skipped. Therefore, it is possible to recognize that another wireless terminal is not receiving interference on CH2. When recognizing that the start beacon of CH3 does not include the interference information of CH2, the wireless terminals 6, 9 and 10 transmit an intermediate beacon including CH2 interference information (information indicating that CH2 should be skipped) to CH3. Transmit between start and end beacons.

  The transmission timing can be determined at any timing by the wireless communication system. For example, an intermediate beacon transmission section may be provided, or an intermediate beacon may be transmitted at an appropriate time at a transmittable timing. In addition, as shown in FIG. 16, when the wireless terminal 6 first transmits the intermediate beacon, the wireless terminals 9 and 10 do not transmit the intermediate beacon. By doing so, the transmission / reception period of the data information can be effectively used.

  In FIG. 15 and FIG. 16, only CH2 is interfered. However, even when both CH2 and CH3 are interfered, each wireless terminal transmits and receives the interference information by the start beacon and the end beacon on CH1. It can be carried out. If the beacon cannot be transmitted and received on all channels, as described above, each wireless terminal waits on the initial channel until a beacon can be received.

(How to correct the synchronization gap)
Next, a method of correcting a synchronization shift will be described.
Since each wireless terminal has the timer unit 236, the frequency channel can be switched regularly at a cycle obtained by adding a transmission / reception period of the start beacon and a transmission / reception period of the end beacon to Tms defined in advance. However, synchronization is basically achieved by receiving a start beacon and an end beacon.

  On the other hand, in addition to the case where the wireless terminal cannot receive the beacon due to interference or the like, there is a possibility that the channel switching timing may be too early or too late due to the clock frequency shift of the timer unit 236 or the like.

  FIG. 17 shows a procedure of resynchronization by receiving a beacon.

  The beacon receiving terminal 1701 in FIG. 17 is a diagram illustrating a case where the timing of switching channels from CH1 to CH2 is too early. In this case, the beacon receiving terminal 1701 can receive a start beacon at a normal timing on the channel switching destination CH2 and reset the timer unit 236 of the beacon receiving terminal 1701 to resynchronize with another wireless terminal. . That is, since the time reset information is included at the end of the start beacon, the beacon receiving terminal 1701 can reset the timer unit 236 upon completion of the reception of the start beacon.

  The beacon receiving terminal 1702 in FIG. 17 is a diagram illustrating a case where the channel switching timing from CH1 to CH2 is too late. In this case, the beacon receiving terminal 1702 can receive the end beacon at normal timing on the channel switching destination CH2. Therefore, based on the CH switching information included at the end of the end beacon, beacon receiving terminal 1702 can switch to CH3 upon completion of reception of the end beacon and resynchronize with another wireless terminal.

  As shown in FIG. 17, when a shift within Tms, which is the length of a predetermined transmission frame, occurs, the wireless terminal receives a start beacon or an end beacon on the channel to which the wireless terminal has switched. , It is possible to resynchronize with another wireless terminal. If the synchronization is lost for a time equal to or longer than Tms, as described above, the wireless terminal waits in the initial channel until a beacon can be received.

  FIG. 18 is a diagram illustrating a state in which resynchronization is performed when the beacon transmitting terminal is out of synchronization.

  In FIG. 18, the wireless terminal 2 that is a beacon transmitting terminal transmits an end beacon at intervals of Tms or more. However, the wireless terminals other than the wireless terminal 2 automatically switch the communication channel to CH3 at a timing including the reception period of the end beacon that should have been received after the elapse of Tms from the reception of the start beacon. Therefore, the timing of switching the channel to the wireless terminal 2 is later than that of the other wireless terminals. However, when receiving the end beacon from the wireless terminal 3 on CH3, the wireless terminal 2 switches from CH3 to CH1, and can re-synchronize with another wireless terminal on CH1.

  In this case, since wireless terminals other than the wireless terminal 2 cannot receive the end beacon on CH2, it is determined that there is interference on CH2, and the CH2 skip operation is performed. That is, at the next timing when the wireless terminal switches from CH1 to CH2, the wireless terminal switches from CH1 to CH3 without switching from CH1 to CH2. Further, when receiving the end beacon from the wireless terminal 3 on CH3, it is determined that there is interference on CH2, and the skip operation of CH2 can be performed.

  Next, when the wireless terminal 4 is a beacon transmitting wireless terminal, the wireless terminal 4 transmits an end beacon at a timing equal to or less than Tms from the transmission of the start beacon, and performs channel switching. The wireless terminal 4 transmits the end beacon when the transmission frame length is equal to or less than the specified transmission frame length Tms, and the other wireless terminals that have received the end beacon also switch channels at the same timing as the wireless terminal 4. As described above, when each wireless terminal receives the end beacon, it performs a channel switching operation, so that synchronization can be established between the wireless terminals.

  As shown in FIG. 18, if the deviation is within the prescribed transmission frame length Tms, the wireless terminal that is the beacon transmitting terminal can resynchronize with another wireless terminal. If the synchronization is shifted by Tms or more, as described above, the wireless terminal waits on the initial channel until a beacon can be received.

As described above, according to the present embodiment. Each wireless terminal can operate independently without installing a control station.
Further, since all wireless terminals regularly communicate by changing the frequency channel, there is no need to wait for a long time on the same frequency channel, and there is no need to carry out carrier sensing in all frequency bands before starting communication.
Furthermore, since the frequency band used is unified for all wireless terminals, it is not necessary to estimate the frequency band used for transmission by correlation.
Furthermore, the priority processing section is assigned only when there is a transmission request to the beacon transmission terminal, so that when there is no transmission request to the beacon transmission terminal, other wireless terminals can efficiently use the transmission frame.
Furthermore, even if only a specific wireless terminal receives interference, the channel is automatically switched, so that the beacon at the channel switching destination can receive interference information and synchronize with another wireless terminal.
Furthermore, since synchronization is performed between the first and last two beacons of a transmission frame, any deviation within the transmission frame length can be re-synchronized with the beacon. Further, even when synchronization is completely lost, the mobile station waits on the initial channel, so that re-synchronization with another wireless terminal becomes possible.

(Modification 1)
In the above-described embodiment, when a particular channel is interfered, the next switching to that channel is skipped and the next channel after the interfered channel is switched. For example, when CH2 is interfered, the communication channel switches from CH1 to CH3 to CH1 to CH2 to CH3. However, after switching to the channel before the interfered channel, the interfered channel may be skipped. For example, when CH2 is interfered, the communication channel switches from CH1 to CH1 to CH3 to CH1 to CH2 to CH3. It is also possible to set such a skip rule of the interference channel as a predetermined rule.

(Modification 2)
In FIG. 1, all wireless terminals are included in the wireless communication network. However, as shown in FIG. 19, there may be wireless terminals that cannot directly communicate with each other. In this case, a wireless communication network can be formed by using the relay transmission.

For example, a case where the wireless terminal 1 belonging to the wireless communication network 1901 is a beacon transmitting terminal will be described. The wireless terminal 4 that has received the start beacon and / or the end beacon transmitted by the wireless terminal 1 relays the start beacon and / or the end beacon to the wireless terminals 5 to 10 that do not belong to the wireless communication network 1901. Alternatively, the wireless terminal 2 or 3 that has received the start beacon and / or the end beacon transmitted by the wireless terminal 1 relays and transmits to the wireless terminals 5 to 7, and the wireless terminal 7 transmits the start beacon and / or Relay the end beacon.
In this way, by using the relay transmission, one wireless communication network can be formed by the wireless communication network 1901, the wireless communication network 1902, and the wireless communication network 1903.

(Modification 3)
When establishing a wireless communication network in a vehicle, the above-described communication control method can be adopted for all wireless terminals in the vehicle. As a result, it is possible to construct a wireless communication network that can cope with interference from another wireless communication system outside the vehicle and interference from other wireless terminals and wireless devices brought into the same vehicle. In addition, the above-described communication control method can be similarly applied to wireless devices such as factories regardless of the inside of a vehicle. In addition, a method other than the CSMA / CA method can be adopted as the wireless communication method.

  Although various embodiments have been described above, some or all of the embodiments may be combined into a new embodiment.

  INDUSTRIAL APPLICABILITY The present invention is extremely useful when used in a wireless network that performs communication control for avoiding an increase in communication delay time due to radio wave interference with another wireless communication system and a communication disabled state.

200 wireless terminal 210 communication unit 211 transmission / reception switching unit 212 wireless transmission unit 213 wireless reception unit 220 determination unit 221 reception intensity determination unit 222 -Interference determination unit 230 ... control unit 231 ... beacon generation unit 232 ... data generation unit 233 ... beacon analysis unit 234 ... channel switching unit 235 ... data processing unit 236 ... timer Unit 240: I / F (interface) unit 250: Information recording unit

Claims (10)

A beacon transmission terminal for a wireless communication system in which one of a plurality of wireless terminals is a beacon transmission terminal in a predetermined order each time a communication channel is switched and the remaining wireless terminals are beacon reception terminals,
A beacon generator for generating a start beacon and an end beacon,
A communication unit for transmitting and receiving the start beacon, data information and the end beacon,
A timer unit that measures a communication channel switching cycle of the communication unit,
A channel switching unit that switches the communication channel of the communication unit according to a predetermined rule in accordance with the switching cycle of the communication channel,
The beacon generation unit includes the start beacon including interference channel skip information including communication channel information of a communication channel that has caused interference, and reset information for resetting a timer unit of a beacon receiving terminal that receives the start beacon. The termination beacon includes interference channel skip information including communication channel information of a communication channel that has caused interference, and channel switching information indicating a timing of switching the communication channel, and transmits the termination beacon from another beacon transmitting terminal. If reception is not possible, the communication channel information of the communication channel of the end beacon is included in the interference channel skip information,
The interference channel skip information of the start beacon includes interference channel skip information of the own wireless terminal and interference channel skip information received from another beacon transmitting terminal,
The interference channel skip information of the end beacon includes interference channel skip information of the start beacon and interference channel skip information of the own wireless terminal,
The communication unit transmits the start beacon before the start of a specified time that is the transmission and reception period of the data information, and transmits the end beacon when the specified time ends,
The channel switching unit, at the end of the communication channel switching cycle from the timing of starting transmission of the start beacon to the timing of completion of transmission of the end beacon, the interference channel skip information included in the end beacon, A beacon transmission terminal, wherein the communication channel is switched based on the predetermined rule and the timer unit is reset. The communication unit further receives an intermediate beacon transmitted from the beacon receiving terminal between the start beacon and the end beacon,
The communication unit further includes a beacon analysis unit that analyzes the interference channel skip information included in the intermediate beacon received,
If the communication channel information of the communication channel having the interference included in the interference channel skip information analyzed by the beacon analysis unit is not included in the interference channel skip information of the start beacon, the beacon generation unit is The beacon transmitting terminal according to claim 1, wherein the communication channel information is included in interference channel skip information of an end beacon.   When the communication unit receives the end beacon transmitted by another beacon transmitting terminal, the channel switching unit includes the end beacon included in the end beacon at the end of receiving the channel switching information included in the end beacon. The beacon transmission terminal according to claim 1 or 2, wherein the communication channel is switched based on interference channel skip information and the predetermined rule, and the timer unit is reset.   The start beacon further includes transmission request information, and when the transmission request information is activated, a priority processing period in which the beacon transmission terminal transmits data information preferentially after transmitting the start beacon is included. 4. The wireless communication apparatus according to claim 1, wherein when the transmission request information is not activated, the beacon receiving terminal can transmit data information without providing the priority processing period. A beacon transmission terminal according to any one of the above.   When the interference channel skip information includes the communication channel information of the communication channel having the interference, when the communication channel of the switching destination is in the order of the communication channel having the interference, the communication channel of the interference has A rule for switching the communication channel to a communication channel next to the communication channel having the interference is set as the predetermined rule while maintaining the previous communication channel and switching the maintained communication channel. The beacon transmitting terminal according to any one of claims 1 to 4, wherein: A beacon receiving terminal of a wireless communication system in which one of a plurality of wireless terminals is a beacon transmitting terminal in a predetermined order each time a communication channel is switched and the remaining wireless terminals are beacon receiving terminals,
A communication unit that transmits and receives a start beacon, data information, and an end beacon,
A timer unit that measures a communication channel switching cycle of the communication unit,
A channel switching unit that switches the communication channel of the communication unit according to a predetermined rule in accordance with the switching cycle of the communication channel,
A determination unit that determines the presence or absence of the interference of the communication channel, and records the communication channel information of the communication channel having the interference in the interference channel skip information of the beacon receiving terminal,
Beacon analysis for analyzing the interference channel skip information included in the start beacon and the end beacon received by the communication unit and adding the communication channel information included in the interference channel skip information to the interference channel skip information of the beacon receiving terminal Part,
The timer unit terminates reception of reset information included in the start beacon in the communication unit, or resets when the channel switching unit switches the communication channel, and receives channel switching information included in the end beacon. Time the switching cycle of the communication channel up to the point where it should be completed,
The channel switching unit,
When receiving the end beacon, when the reception of the channel switching information included in the end beacon is completed, the communication channel is set based on the interference channel skip information included in the end beacon and the predetermined rule. switching,
When not receiving the end beacon, the determination unit records the communication channel information of the communication channel of the end beacon in the interference channel skip information of the beacon receiving terminal, and the timer unit switches the channel included in the end beacon. A beacon receiving terminal that switches a communication channel based on the interference channel skip information of the beacon receiving terminal and the predetermined rule when indicating a time point at which reception of information is to be completed.   Prior to receiving the start beacon, if the start beacon does not include the interference channel skip information of the communication channel, even though the communication channel has received interference from another wireless communication system, The beacon receiving terminal according to claim 6, further comprising: a beacon generator configured to generate an intermediate beacon including the interference channel skip information of (b), wherein the communication unit transmits the intermediate beacon.   The start beacon further includes transmission request information, and when the transmission request information is activated, a priority processing period in which the beacon transmission terminal transmits data information preferentially after transmitting the start beacon is included. 8. The wireless communication system according to claim 6, wherein when the transmission request information is not activated, the beacon receiving terminal can transmit data information without providing the priority processing period. 2. A beacon receiving terminal according to item 1.   If the communication unit does not receive the start beacon and the end beacon continuously on all communication channels, the channel switching unit uses the communication channel set at the beginning of the switching order of the communication channel, the start beacon. The beacon receiving terminal according to any one of claims 6 to 8, wherein the terminal waits for reception of an end beacon. A beacon transmission terminal according to any one of claims 1 to 5,
A wireless communication system comprising: the beacon receiving terminal according to claim 6.