JP5522092B2 - Wireless communication apparatus and wireless communication system - Google Patents

Description

  The present invention is a wireless device including two types of communication devices, a first communication device having a periodic transmission function and a second communication device having a random transmission function, as communication devices that perform wireless communication using a common communication channel. The present invention relates to a communication system and a radio communication apparatus suitable for constituting a first communication apparatus of the radio communication system.

  Conventionally, in a wireless communication system in which a plurality of communication devices start data transmission randomly using a common communication channel, such as a CSMA wireless communication system, for example, a specific communication device serving as a base station is important. Even when trying to transmit high information (important information), it takes time to acquire the transmission right through the communication channel, and there is a problem that the important information cannot be transmitted promptly.

  Therefore, in this type of wireless communication system, apart from a communication apparatus (second communication apparatus) having a random transmission function for starting data transmission at random using a communication system such as CSMA, important information is transmitted using a communication system such as TDMA. Proposed to provide a communication device (first communication device) having a periodic transmission function for periodically transmitting, and prohibit random transmission by the second communication device during the periodic transmission period in which the first communication device periodically transmits. (For example, see Patent Document 1).

  Further, in the proposed wireless communication system, when the first communication device periodically transmits, the periodic transmission period information indicating the periodic transmission period is included in the transmission data to notify the second communication device of the periodic transmission period, Further, when the second communication device that has received the periodic transmission period information performs random transmission, the transmission data includes the periodic transmission period information so that the transmission radio wave from the first communication device is not received. The periodic transmission period information is transferred to the second communication device.

  For this reason, according to the proposed wireless communication system, the second communication device limits the random transmission period during which random transmission is performed, and causes the first communication device to preferentially transmit the important information to the surrounding second communication devices. be able to.

JP 2010-21870 A

  However, in the proposed wireless communication system, since the first communication device performs periodic transmission within a preset periodic transmission period, for example, when a plurality of first communication devices are installed at close positions as roadside devices, It is conceivable that radio wave interference occurs between the plurality of first communication devices.

  In order to prevent this problem, the periodic transmission periods of the first communication apparatuses may be allocated so that the periodic transmission periods do not overlap between adjacent first communication apparatuses. In the case of newly installing a device, within the communication area of the newly installed first communication device, the received power of the transmitted radio wave from the first communication device and the received power of the transmitted radio wave from a nearby roadside device Each of the existing roadside equipment that may cause interference of the transmission radio wave with the newly installed first communication device, and the periodic transmission period used by the existing roadside equipment, In order not to overlap, it is necessary to set the periodic transmission period of the newly installed first communication device.

For this reason, when the first communication device is newly installed as a roadside device, it is necessary to set a regular transmission period, and there is a problem that it takes cost and time for that.
In addition, after the first communication device is installed as a roadside machine, if a surrounding radio wave environment changes, for example, when a building is newly built or demolished around the roadside machine, it is between the adjacent roadside machine. It is also conceivable that radio wave interference occurs and communication becomes impossible.

  In order to prevent this problem, it is only necessary to re-measure the power and reassign the periodic transmission period as in the case of newly installing a roadside device. Not only does this take time, but the problem also arises that the service must be temporarily stopped.

  The present invention has been made in view of such problems, and the first communication device having the periodic transmission function and the second communication device having the random transmission function are mixed, and the first communication device transmits the periodic transmission period information. The second communication device receives the periodic transmission period information and transfers it to the other second communication devices, so that each second communication device grasps the periodic transmission period of the first communication device and is randomly within that period. In a wireless communication system in which transmission is not performed, a periodic transmission period is set so that a first communication device itself having a periodic transmission function does not cause transmission radio wave interference with another first communication device. The purpose is to enable automatic assignment.

In order to achieve this object, the inventions according to claims 1 and 2 are similar to the above-described conventional wireless communication system, in that a plurality of first communication devices having a periodic transmission function and a plurality of first communication devices having a random transmission function. The present invention relates to a wireless communication device used as a first communication device in a wireless communication system in which two communication devices are mixed.

  In the wireless communication system in which the wireless communication apparatus of the present invention is used, the plurality of first communication apparatuses are configured to periodically transmit data including periodical transmission period information indicating the periodical transmission period, and the plurality of second communications. When receiving a signal including periodic transmission period information from the first communication apparatus or another second communication apparatus, the apparatus performs random transmission within the periodic transmission period corresponding to the periodic transmission period information included in the received signal. The transmission period is limited so as not to occur, and the restored periodic transmission period information is transferred to another communication device.

  And in this radio | wireless communications system, in the radio | wireless communication apparatus of this invention used as a 1st communication apparatus, a receiving means is transmitted from a 2nd communication apparatus and another 1st communication apparatus using a predetermined | prescribed communication channel. The incoming transmission signal is received, the received data is restored, the periodic transmission period setting means extracts the periodic transmission period information from the received data restored by the receiving means, and based on the extracted periodic transmission period information The periodic transmission period in which the wireless communication apparatus performs periodic transmission is set so as not to overlap with the periodic transmission periods of the other first communication apparatuses.

  In other words, in the wireless communication apparatus of the present invention, the periodic transmission period setting means performs periodic transmission in which the other first communication apparatus performs periodic transmission based on the periodic transmission period information included in the received data received from the other communication apparatus. A periodical transmission period different from the period is automatically set as its own periodical transmission period.

  Therefore, according to the wireless communication device of the present invention, in the above-described wireless communication system, when the wireless communication device is newly provided as the first communication device, or from the wireless communication device in response to changes in the surrounding radio wave environment. When the periodic transmission period of the first communication device is reassigned, the periodic transmission period is automatically set so that the transmission radio wave from the wireless communication device does not interfere with the transmission radio wave from the other first communication device. The time and cost required for the setting can be reduced.

Moreover, in the wireless communication device according to claim 1 among the wireless communication devices according to claims 1 and 2 , a plurality of periodic transmission periods are set in advance as periodic transmission periods that can be set by the periodic transmission period setting means . The periodic transmission period setting means selects a periodic transmission period that is not used by another first communication device from among the plurality of periodic transmission periods .
Good.

For this reason , in the above wireless communication system, the first communication device uses one periodic transmission period different from that of the other first communication devices from among the plurality of periodic transmission periods prepared in advance. As compared with the case where each first communication device arbitrarily sets the periodic transmission period, the periodic transmission periods in which the plurality of first communication devices perform the periodic transmission within one period of the periodic transmission. Can be allocated efficiently.

  Also, in this case, when preparing a plurality of periodic transmission periods, a random transmission period used for random transmission by the second communication device is secured by providing an empty period that is not allocated as a periodic transmission period within one period of periodic transmission. You can also

In order to operate the periodic transmission period setting unit in this manner, in the wireless communication device according to claim 1 , the periodic transmission period setting unit is configured to perform a plurality of periodic transmissions stored in advance based on the periodic transmission period information. From the period, the periodical transmission period extracting unit that extracts the periodical transmission period that is not used by another first communication device, and the periodical transmission period that is extracted by the periodical transmission period extracting unit, The wireless communication apparatus includes periodic transmission period selection means for selecting a periodic transmission period for performing periodic transmission .

By the way, when the wireless communication apparatus is configured as described above , not only the periodic transmission period information directly transmitted from the first communication apparatus but also the periodic transmission period information transferred from the second communication apparatus, Since its own periodic transmission period is set, the transmission radio wave from the radio communication device is within the communication area of the radio communication device even if the radio communication device does not receive the radio wave transmission from the other first communication device. Can be prevented from interfering with radio waves transmitted from other first communication devices.

  However, when the second communication device does not exist in the overlap area where the transmission radio wave from the other first communication device reaches within the communication area of the wireless communication device, or the second communication within the communication area of the other first communication device. When the communication failure occurs between the device and the second communication device in the communication area of the wireless communication device, the periodic transmission period information of the other first communication device necessary for setting the periodic transmission period is the first. It is also conceivable that the data is not transferred via the two communication devices.

  In this case, the periodic transmission period of the other first communication device is extracted as an empty periodic transmission period, and the extracted empty periodic transmission period may be set as the periodic transmission period of the wireless communication device. is there.

Therefore, in order to prevent this problem with certainty, in the wireless communication device according to claim 1, the idle periodic transmission period extracting means is used for periodic transmission included in the received data from the other first communication device. Based on the period information, the first extraction means for extracting the vacant periodical transmission period and the periodical transmission period information included in the received data from the second communication apparatus, the other first communication apparatuses are more than a predetermined number of times of determination. The periodical transmission period determined not to be used is composed of second extraction means for extracting the periodical transmission period as an empty periodical transmission period, and the periodical transmission period selection means is a periodical idle period in both the first extraction means and the second extraction means. A periodical transmission period in which the wireless communication apparatus performs periodical transmission is selected from the idle periodical transmission periods extracted as the transmission period .

  In other words, in this way, when the idle periodic transmission period extracting means extracts the idle periodic transmission period based on the regular transmission period information transferred from the second communication device, the second extracting means Based on a plurality of periodic transmission period information received from the communication device, only the periodic transmission periods determined to be free for a predetermined number of times or more are extracted as the free periodic transmission periods.

  Therefore, when the second extraction unit cannot acquire the periodic transmission period information necessary for setting the periodic transmission period from the second communication device, the periodic transmission period corresponding to the periodic transmission period information is not available. Extraction as a periodic transmission period can be suppressed.

Therefore, according to the wireless communication apparatus according to claim 1, regular transmission period of the first communication device other reaching the communication area of the wireless communication device is set incorrectly as the periodic transmission period of the wireless communication device Can reduce the probability.

On the other hand, in the above-described wireless communication system, the second communication device transfers the periodic transmission period information acquired from the first communication device or the second communication device, so that it is transferred from the second communication device to the wireless communication device of the present invention. It is also conceivable that the periodic transmission period information is from a distant first communication device that does not cause radio wave interference.

  Thus, even when the periodic transmission period information from the first communication device that does not cause radio wave interference is transferred via the second communication device, the wireless communication is performed based on the periodic transmission period information. If the periodical transmission period of the device is set, the number of idle periodical transmission periods that can be set as the periodical transmission period of the wireless communication apparatus decreases, and in some cases, it may be impossible to set the periodical transmission period.

For this reason, when the second communication device constituting the wireless communication system transfers the periodic transmission period information restored from the received signal, the second communication is performed after the periodic transmission period information is transmitted from the first communication device. In the case where it is configured to give transfer count information indicating the transfer count transferred by the apparatus, the periodic transmission period setting means may be configured as described in claim 2 .

That is, in the wireless communication device according to claim 2 , the periodic transmission period setting means detects the number of transfers of the periodic transmission period information based on the transfer number information given to the periodic transmission period information extracted from the received data. However, periodic transmission period information whose number of transfers is equal to or greater than a preset upper limit value is excluded from the periodic transmission period information used for setting the periodic transmission period of the wireless communication device.

Therefore, according to the wireless communication apparatus according to claim 2, the number of transfers by the second communication device number, the regular transmission period information from the first communication device the distance is considered a long between the wireless communication device Based on this, it is possible to prevent the periodical transmission period of the wireless communication apparatus from being unnecessarily limited, and the settable range of the periodical transmission period can be expanded.
In the wireless communication device according to claim 2, as described in claim 3, it is preferable that the periodic transmission period setting unit includes an empty regular transmission period extraction unit and a periodic transmission period selection unit. .
Further, in this case, as described in claim 4, the empty regular transmission period extraction unit includes a first extraction unit and a second extraction unit, and the regular transmission period selection unit includes the first extraction unit and the first extraction unit. It is good to comprise so that the periodical transmission period which the said radio | wireless communication apparatus may perform periodical transmission may be selected from the periodical idle transmission periods extracted as the periodical idle transmission period by both 2 extraction means.
That is, in this way, an effect similar to that of the above-described claim 1 can be obtained.

Next, in order to widen the settable range of the regular transmission period, whether or not the reception level of the received data has reached a preset determination level in the regular transmission period setting means as described in claim 5. The periodic transmission period information of received data whose reception level does not reach the determination level may be excluded from the periodic transmission period information used for setting the periodic transmission period of the wireless communication device.

  That is, when the reception level of the reception data is low, the distance between the communication device that has transmitted the reception data and the wireless communication device is long, and the first communication device that is the transmission source of the periodic transmission information included in the reception data In the wireless communication device according to claim 5, when the reception level of the reception data does not reach the determination level, the periodicity included in the reception data is low. The transmission period information is excluded from the periodic transmission period information used for setting the periodic transmission period of the wireless communication device.

Therefore, also in the wireless communication device according to claim 5, like the wireless communication device according to claim 2, it is possible to prevent the periodic transmission period of the wireless communication device from being unnecessarily limited, The settable range of the regular transmission period can be expanded.

When applying the technique according to claim 5 to the wireless communication apparatus according to claim 2 , the periodic transmission period setting means, for example, for periodic transmission period information whose number of transfers has not reached the upper limit value. Determines whether or not the number of transfers is greater than or equal to the lower limit (a value smaller than the upper limit). If the number of transfers is less than the upper limit and greater than or equal to the lower limit, the reception level of the periodic transmission period information is set in advance. If the reception level of the periodic transmission period information does not reach the determination level, the periodic transmission period information is used for setting the periodic transmission period of the wireless communication device. Exclude it from the periodical transmission period information.

  On the other hand, in the above-described wireless communication device of the present invention, the periodic transmission period information from another first communication device does not reach the wireless communication device, or the periodic transmission period information from the other first communication device is transferred. When the coming second communication device does not exist in the communication area of the wireless communication device, the periodic transmission period of the other first communication device is erroneously set as the periodic transmission period of the wireless communication device. It cannot be completely prevented.

  Then, when the wireless communication device of the present invention is operated so as to periodically transmit in the periodic transmission period erroneously set as described above, radio wave interference with other first communication devices within the communication area of the wireless communication device. As a result, the second communication device existing in the communication area of the wireless communication device cannot normally receive the transmission data from the wireless communication device.

Therefore, in order to prevent this problem, it is preferable to provide periodic transmission determination means separately as in the radio communication apparatus according to claim 6.
That is, in the wireless communication device according to claim 6, when the periodic transmission determining unit sets the periodic transmission period by the periodic transmission period setting unit, and the wireless communication device starts the periodic transmission within the periodic transmission period. Thereafter, it is determined whether or not data including the periodic transmission period information of the wireless communication apparatus can be received from the second communication apparatus, and data including the periodic transmission period information of the wireless communication apparatus cannot be received from the second communication apparatus. In some cases, the periodic transmission period setting unit is caused to reset the periodic transmission period.

  Therefore, according to the wireless communication apparatus of the sixth aspect, the periodic transmission period information of the wireless communication apparatus cannot be received from the second communication apparatus, and the periodic transmission period of the wireless communication apparatus is different from the first transmission period. When there is a possibility that the same periodic transmission period as that of the communication device is erroneously set, the periodic transmission period setting means can reset the periodic transmission period.

  Therefore, according to the wireless communication device of the sixth aspect, radio wave interference occurs with another first communication device, and the second communication device existing in the communication area of the wireless communication device is connected to the wireless communication device. It is possible to prevent the transmission data from the apparatus from being normally received.

  Next, the invention according to claim 7 has a periodic transmission function for performing wireless transmission within a periodic transmission period shorter than the predetermined period at predetermined intervals using a predetermined communication channel. Moreover, at the time of periodic transmission, a plurality of first communication devices configured to transmit data including periodic transmission period information indicating the periodic transmission period, and whether or not the communication channel is free when a transmission request is generated And a plurality of second communication devices having a random transmission function for performing wireless transmission when the communication channel is free are mixed, and each second communication device is a first communication device. When a signal including periodic transmission period information is received from the communication device or another second communication device, the periodic transmission period information is restored from the received signal, and random transmission is performed within the periodic transmission period corresponding to the periodic transmission period information. The present invention relates to a wireless communication system configured to limit its own transmission period so as not to be applied and to transfer the restored periodic transmission period information to another communication apparatus using the communication channel. .

And in the radio | wireless communications system of Claim 7, several 1st communication apparatuses are each comprised by the radio | wireless communication apparatus of any one of Claims 1-6.
For this reason, according to the wireless communication system according to claim 7, the periodic transmission periods in which the plurality of adjacent first communication devices perform periodic transmission overlap, and the second communication in the communication area of each first communication device. It is possible to prevent the device from performing normal communication.

  In addition, since each first communication device can automatically set its own periodic transmission period, it is possible to reduce the cost and time required to set or change the periodic transmission period of each first communication device, Communication system construction and maintenance can be realized at low cost.

It is explanatory drawing showing the outline | summary of a structure and operation | movement of the radio | wireless communications system of 1st Embodiment. It is a block diagram showing the structure of the regular transmission terminal of 1st Embodiment. It is a block diagram showing the structure of the random transmission terminal of 1st Embodiment. It is a flowchart showing the idle regular transmission period setting process performed in the regular transmission terminal of 1st Embodiment. It is a flowchart showing the empty determination process A performed in the empty regular transmission period setting process of 1st Embodiment. It is a flowchart showing the idle regular transmission period setting process performed in the regular transmission terminal of 2nd Embodiment. It is a flowchart showing the empty determination process B performed in the empty regular transmission period setting process of 2nd Embodiment. It is a block diagram showing the structure of the regular transmission terminal of 3rd Embodiment. It is a flowchart showing the idle regular transmission period setting process performed in the regular transmission terminal of 3rd Embodiment. It is a flowchart showing the empty determination process C performed in the empty regular transmission period setting process of 3rd Embodiment. It is a block diagram showing the structure of the regular transmission terminal of 4th Embodiment. It is a flowchart showing the idle regular transmission period setting process performed in the regular transmission terminal of 4th Embodiment. It is a flowchart showing the idle regular transmission period determination process performed after a regular transmission period selection in the idle regular transmission period setting process of 4th Embodiment. It is a flowchart showing the empty determination process D performed in the empty regular transmission period determination process of 4th Embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
(Configuration of the entire wireless communication system)
FIG. 1 is an explanatory diagram showing an outline of the configuration and operation of a wireless communication system according to the first embodiment to which the present invention is applied. Note that the wireless communication system of the present embodiment is configured in substantially the same manner as the embodiment described in Patent Document 1 described above.

  As shown in FIG. 1 (a), the wireless communication system of the present embodiment includes a plurality of periodic transmission terminals 2 (2a and 2b shown in the figure) installed as roadside devices in the vicinity of the traveling road of an automobile, It is composed of a plurality of random transmission terminals 4 (4a and 4b shown in the figure) that are mounted on an automobile and wirelessly communicate with roadside units and other vehicles.

  The periodic transmission terminal 2 corresponds to the first communication device of the present invention (in other words, the wireless communication device of the present invention), and a periodic transmission function for periodically transmitting various information such as traffic information to surrounding vehicles. Have

  The random transmission terminal 4 corresponds to the second communication device of the present invention, and receives a transmission request from a control device mounted on an automobile, and changes the state of the own vehicle to a roadside machine or another vehicle. It has a random transmission function to transmit.

  A common communication channel is used for road-to-vehicle communication between the regular transmission terminal 2 and the random transmission terminal 4 and vehicle-to-vehicle communication between the random transmission terminals 4, and the random transmission terminal 4 performs random transmission. First, it is determined whether or not the communication channel is free by CSMA access control, and data transmission is started when the communication channel is free.

  In addition, the periodical transmission period by the periodical transmission terminal 2 is determined in advance, and each periodical transmission terminal 2 can determine which period within one periodical transmission period when it is installed near the road or when the setting of the system is changed. Is used as a regular transmission period so that the regular transmission period does not overlap with other regular transmission terminals 2.

  Then, each periodic transmission terminal 2 (2a, 2b) transmits periodic transmission period information indicating the periodic transmission period (period α, period β shown in FIG. 1C) to the surrounding random transmission terminals 4 ( 4a, 4b), and each random transmission terminal 4 (4a, 4b) prohibits random transmission during the notified regular transmission periods α, β.

  That is, in this embodiment, the periodic transmission terminal 2 having the periodic transmission function adds the periodic transmission information shown in FIG. 1B to the transmission data and periodically transmits the data, and the random transmission terminal 4 receives the periodic transmission information. Then, as shown in FIG. 1 (c), its own random transmission prohibition period is set based on the periodic transmission information, and random transmission is performed within a period (random transmission period) other than the random transmission prohibition period. .

  As shown in FIG. 1B, the periodic transmission information includes periodic transmission terminal 2 that performs periodic transmission in periodic transmission period information that represents the start timing of the periodic transmission period and the length (period length) of the periodic transmission period. Device ID (for example, MAC address) and transfer count C (initial value: 0) which will be described later.

  By the way, as shown in FIG. 1A, when the random transmission terminal 4a is located in a communication area where the transmission radio wave from the regular transmission terminal 2a reaches and the random transmission terminal 4b is located outside the communication area. The regular transmission information transmitted from the regular transmission terminal 2a does not reach the random transmission terminal 4b.

  Therefore, the random transmission terminal 4b starts random transmission within the regular transmission period of the regular transmission terminal 2a, and the random transmission terminal 4a includes a transmission radio wave from the regular transmission terminal 2a, a transmission radio wave from the random transmission terminal 4b, and May arrive at the same time, making it impossible to receive each transmission data.

  Therefore, in this embodiment, for example, in FIG. 1A, when the random transmission terminal 4a receives the periodic transmission information, the received periodic transmission information is notified to the other random transmission terminals 4b. .

  That is, each random transmission terminal 4 retransmits the periodic transmission information by adding the periodic transmission information to the transmission data when receiving the periodic transmission information from the periodic transmission terminal 2 or other random transmission terminals 4.

  When each random transmission terminal 4 retransmits the periodic transmission information, the number of transfers C included in the periodic transmission information is updated (+1). As a result, on the terminal side that has received the periodic transmission information transmitted from the random transmission terminal 4, it is possible to identify how many times the periodic transmission information has arrived in the first transfer since the periodic transmission terminal 2 first transmitted. become.

  Further, in order to set the random transmission prohibition period based on the regular transmission information on the random transmission terminal 4 side, the periodic transmission period recognized on the regular transmission terminal 2 side and the random transmission terminal 4 side are recognized. It is necessary to match the periodic transmission cycle.

  Therefore, in this embodiment, when the periodic transmission terminal 2 transmits the periodic transmission information or when the random transmission terminal 4 retransmits (transfers) the periodic transmission information, the transmission time is set to its own clock 26, 50 ( 2 (see FIGS. 2 and 3) and added to the periodic transmission information (see FIG. 1 (b)).

  Then, the random transmission terminal 4 that has received the periodic transmission information compares the transmission time given to the periodic transmission information with the reception time read from its own clock 50, so that the time of the clock 50 is periodically updated. The transmission information is synchronized with the time on the regular transmission terminal 2 or random transmission terminal 4 side that has transmitted the transmission information.

  That is, for example, in FIG. 1A, the random transmission terminal 4a acquires the periodic transmission information from the periodic transmission terminal 2a, and the random transmission terminal 4b acquires the periodic transmission information from the random transmission terminal 4a. When the random transmission terminals 4a and 4b receive the regular transmission information, the random transmission terminals 4a and 4b synchronize the time of their clock 50 with the clock of the regular transmission terminal 2a or the random transmission terminal 4a that has transmitted the regular transmission information.

As a result, the clocks 50 of the random transmission terminals 4 that have received the periodic transmission information all have the same time as the clock 26 of the periodic transmission terminal 2 that is the transmission source of the periodic transmission information, and each random transmission terminal 4 has its own clock. 50, the periodical transmission period by the periodical transmission terminal 2 can be accurately grasped.
(Configuration of periodic sending terminal)
Next, FIG. 2 is a block diagram showing a configuration of the regular transmission terminal 2 used for constructing the wireless communication system of the present embodiment.

  As shown in FIG. 2, the regular transmission terminal 2 outputs a data transmission unit 12 that adds additional information such as a header to the transmission data to be transmitted to the surrounding random transmission terminals 4, and outputs from the data transmission unit 12. Modulation processing unit 14 that converts the transmitted data into a transmission signal (high-frequency signal) on a predetermined communication channel and outputs the signal to a communication antenna (not shown); A demodulation processing unit 16 that restores transmission data from the transmission terminal (periodic transmission terminal 2 or other random transmission terminal 4), and additional information such as a header is extracted from the reception data restored by the demodulation processing unit 16 and received. If the data is transmitted to the random transmission terminal 4 (4a, 4b), the received data is output to an external data processing device (such as a management device of a wireless communication system). A data receiving unit 18, is provided.

  Further, the periodic transmission terminal 2 has a periodic transmission period table 20 in which periodic transmission period information indicating its own periodic transmission period is stored, and a periodic transmission period setting in which the periodic transmission period is set and written in the periodic transmission period table 20 Unit 30, a periodic transmission period determining unit 22 for determining a periodic transmission period in which the data transmission unit 12 actually performs periodic transmission based on the periodic transmission period information stored in the periodic transmission period table 20, and stored in the periodic transmission period table 20. A periodic transmission information generation unit 24 that generates periodic transmission information to be added to transmission data based on the periodic transmission period information, and a clock 26 that is used by the data transmission unit 12 to detect transmission timing are provided.

  Then, the data transmission unit 12 detects the regular transmission period input from the regular transmission period determination unit 22 based on the time measured by the clock 26, and from the current time information, regular transmission information, etc. during the regular transmission period. The transmission data to which the additional information is added is output to the modulation processing unit 14 to perform periodic transmission.

  Next, the periodical transmission period setting unit 30 corresponds to the periodical transmission period setting means of the present invention. When the periodical transmission period needs to be set, such as when the periodical transmission terminal is installed or when the radio communication system is modified, This is for automatically setting its own periodic transmission period in accordance with the periodic transmission period setting command input from.

  The regular transmission period setting unit 30 includes a regular transmission period candidate storage unit 32, a free regular transmission period determination unit 34, a free regular transmission period table 36, and a regular transmission period selection unit 38.

  Here, the regular transmission period candidate storage unit 32 stores in advance a plurality of regular transmission periods that can be set as the regular transmission period by each regular transmission terminal 2 within one regular transmission cycle as candidates for the regular transmission period. For example, it is composed of a nonvolatile memory capable of rewriting data.

  In addition, the vacant regular transmission period determination unit 34 includes the received data restored by the data reception unit 18 for a determination time T1 longer than one period of regular transmission (for example, a time obtained by multiplying the regular transmission period by several times). From the periodic transmission period candidates stored in the periodic transmission period candidate storage unit 32 based on the periodic transmission period information included in the fetched periodic transmission information, other periodic transmission terminals 2 is used to extract an unused regular transmission period that is not used and write it in an empty regular transmission period table 36 (specifically, a memory), and corresponds to an idle regular transmission period extracting means of the present invention.

  Further, the regular transmission period selection unit 38 selects one of the available regular transmission periods from the available regular transmission periods written in the available regular transmission period table 36 by the available regular transmission period determination unit 34. The periodic transmission period is selected and written to the periodic transmission period table, and corresponds to the periodic transmission period selection means of the present invention.

  The idle regular transmission period determination unit 34 and the regular transmission period selection unit 38 are executed by a microcomputer (not shown) provided in the regular transmission terminal 2 together with the regular transmission period determination unit 22 and the regular transmission information generation unit 24. This is realized by software processing.

The processing executed by the microcomputer in order to realize the function as the empty regular transmission period determination unit 34 will be described in detail later with reference to the flowcharts of FIGS.
(Configuration of random transmission terminal)
Next, FIG. 3 is a block diagram showing the configuration of the random transmission terminal 4 used to construct the wireless communication system of the present embodiment.

As shown in FIG. 3, the random transmission terminal 4 includes a data transmission unit 12, a modulation processing unit 14, a demodulation processing unit 16, and a data reception unit 18, similar to the regular transmission terminal 2.
Further, the random transmission terminal 4 includes a periodic transmission period table 40 (in detail memory) for storing the periodic transmission information acquired from the periodic transmission terminal 2 or other random transmission terminals 4, and a random transmission prohibition period, A random transmission prohibition period determining unit 44 that is determined based on the periodic transmission information (specifically, periodic transmission period information) in the periodic transmission period table 20 and that is output to the data transmission unit 12 is provided.

  When the random transmission prohibition period information is input from the random transmission prohibition period determination unit 44, the data transmission unit 12 prohibits random transmission of transmission data only during the random transmission prohibition period corresponding to the information.

In addition, the random transmission terminal 4 is provided with a clock 50 that measures time, and the data transmission unit 12 detects a random transmission prohibition period based on the time measured by the clock 50.
The random transmission terminal 4 includes a regular transmission period update unit 42 and a time correction unit 52 as functional blocks realized by software processing by a microcomputer.

  The regular transmission period update unit 42 updates the regular transmission information in the regular transmission period table 40 based on the regular transmission information included in the reception data restored by the data reception unit 18. The regular transmission period update unit 42 performs the following regular transmission information transfer process in addition to the process of updating the regular transmission information in the regular transmission period table 40 based on the regular transmission information restored by the data reception unit 18. Also execute asynchronous setting process.

  Periodic transmission information transfer processing: When the number C of transmissions of periodic transmission information received by the data receiver 18 is smaller than a threshold Cmax set in advance for determining whether transfer is necessary, the number C of transmissions of periodic transmission information. Is updated (+1), and the periodic transmission information after the update is output to the data transmission unit 12, so that the periodic transmission information restored by the data reception unit 18 is retransmitted (transferred) from the data transmission unit 12. .

  Asynchronous setting process: When the periodic transmission information registered in the periodic transmission period table 20 is not received for a predetermined time or more, it is determined that the host vehicle is away from the periodic transmission terminal 2 corresponding to the registered periodic transmission information. Thus, the periodic transmission information in the periodic transmission period table 20 is rewritten to asynchronous information that is not used for setting the random transmission prohibition period.

  Further, the time correction unit 52 determines the time measured by the clock 50 and the periodical transmission terminal 2 based on the transmission time given to the periodical transmission information restored by the data reception unit 18 and the reception time of the periodical transmission information. And the amount of deviation (time deviation amount) are obtained, and the time measured by the clock 50 is corrected based on the amount of time deviation.

In the wireless communication system of the present embodiment, the configurations of the regular transmission terminal 2 and the random transmission terminal 4 are basically the same as those described in Patent Document 1 described above, and are the main parts of the present invention. Since the configuration and operation other than the periodic transmission period setting unit 30 in a certain periodic transmission terminal 2 are described in detail in Patent Document 1, the description of the further configuration of the wireless communication system is omitted in this specification. .
(Free periodic transmission period setting process)
Next, in the regular transmission terminal 2, the idle regular transmission period setting process executed by the microcomputer in order to realize the function as the idle regular transmission period determination unit 34 in the regular transmission period setting unit 30 will be described.

FIG. 4 is a flowchart showing an empty regular transmission period setting process.
As shown in FIG. 4, when this process is started, first, in S110 (S represents a step), it is determined whether or not the data receiving unit 18 has received data including periodic transmission information.

  In S110, if the data receiving unit 18 determines that the data including the regular transmission information has not been received, the process proceeds to S150. Conversely, the data receiving unit 18 receives the data including the regular transmission information. If it is determined that it has been performed, the process proceeds to S120.

In S120, the number of transfers C of the periodic transmission information is read from the data receiving unit 18, and it is determined whether or not the number of transfers C is smaller than a preset upper limit value (for example, value “3”).
When the transfer count C is equal to or greater than the upper limit value, the process proceeds to S150. Conversely, when the transfer count C is smaller than the upper limit value (for example, C: 0, 1, 2), S140 is performed. The vacancy determination process A is executed according to the procedure shown in FIG.

  As shown in FIG. 5, in the vacancy determination process A, first, in S210, the periodic transmission period numbers stored in the regular transmission period candidate storage unit 32 in the order of No. 0 to No. 1, No. 2,. After the counter n is set to the initial value “0”, in step S220, is the n-th periodic transmission period corresponding to the counter n coincide with the periodic transmission period of the periodic transmission information acquired from the data receiving unit 18 this time? By determining whether or not, the n-th periodic transmission period is determined to be an “empty” periodic transmission period different from the periodic transmission period of the periodic transmission information acquired this time.

  If it is determined that the nth periodic transmission period is “free”, the process proceeds to S230, and the nth periodic transmission period is provisionally determined to be “free” and stored in a temporary storage memory such as a RAM. Then, the process proceeds to S240.

If it is determined in S220 that the nth regular transmission period is not “vacant”, the process proceeds to S240 as it is.
In S240, the value of the counter n is stored in the periodical transmission period candidate storage unit 32 by determining whether or not the last number N of the periodical transmission period stored in the periodical transmission period candidate storage unit 32 has been reached. It is determined whether or not vacancy determination has been performed for all scheduled transmission periods.

When it is determined in S240 that the value of the counter n has reached “N”, the empty determination process A is terminated.
If it is determined in S240 that the value of the counter n has not reached the value “N”, the value of the counter n is incremented (+1) in S250, and the process proceeds to S220 again.

Returning to FIG. 4, when the vacancy determination process A is executed in S140 as described above, the process proceeds to S150.
In S150, it is determined whether or not the elapsed time t from the start of the idle periodic transmission period setting process exceeds a preset determination time T1 (a fixed time longer than one period of periodic transmission). If the time t does not exceed the determination time T1, the process proceeds to S110 again, and the processes of S110 to S140 are executed.

  On the other hand, if it is determined in S150 that the elapsed time t has exceeded the determination time T1, the process proceeds to S160, and whether or not the vacancy determination process A in S140 has been executed before the determination time T1 elapses. Judging.

  If it is determined in S160 that the vacancy determination process A has been executed during the determination time T1, the process proceeds to S170, and in S230 of the vacancy determination process A, “free” is received for each received periodic transmission information. From the periodic transmission period temporarily determined and stored in the temporary storage memory, the periodic transmission period determined as “free” in all the received periodic transmission information is extracted, and the extracted periodic transmission period is changed to another The free regular transmission period not used by the regular transmission terminal 2 is stored in the free regular transmission period table 36, and the free regular transmission period setting process is terminated.

In S160, when it is determined that the vacancy determination process A cannot be executed during the determination time T1, that is, during the determination time T1, the periodical transmission is performed from another periodic transmission terminal 2 or a surrounding random transmission terminal 4. When data including information is not transmitted, it is determined that the transmission radio waves from other regular transmission terminals 2 do not reach the communication area of the regular transmission terminal 2 and that the transmission radio waves do not interfere with each other. Then, the process proceeds to S180, and all the regular transmission period candidates stored in the regular transmission period candidate storage unit 32 are stored in the free regular transmission period table 36 as free regular transmission periods, and the free regular transmission period setting process is performed. finish.
(Effect of 1st Embodiment)
As described above, in the regular transmission terminal 2 of the present embodiment, when the reception data including the regular transmission information is restored in the data receiving unit 18 as a reception unit, based on the restored regular transmission information, A period in which the periodic transmission period in use that other periodic transmission terminals 2 use for regular transmission is detected, and the regular transmission period stored in the regular transmission period candidate storage unit 32 is excluded from the regular transmission period in use A series of determination processes (S110 to S140) that are temporarily determined with the transmission period as an empty regular transmission period are executed while a predetermined determination time T1 has elapsed.

  Then, during the determination time T1, the other periodic transmission terminals 2 use all the periodic transmission information from the vacant periodic transmission period provisionally determined for each periodic transmission information restored by the data receiving unit 18. The periodical transmission period determined as the unused periodical transmission period is written in the periodical transmission period table 36, and the periodical transmission period selection unit 38 selects the periodical transmission period from the periodical transmission period written in the periodical transmission period table 36. One free regular transmission period used as the regular transmission period of the regular transmission terminal 2 is selected and stored in the regular transmission period table 20.

  Therefore, according to the periodic transmission terminal 2 of the present embodiment, the periodical transmission period of its own is changed so that the transmission radio wave from the regular transmission terminal 2 does not interfere with the transmission radio waves from other periodic transmission terminals 2. It is possible to automatically set a periodic transmission period that does not overlap with the regular transmission terminal 2, thereby reducing the time and cost required for setting the periodic transmission period.

  In the present embodiment, a plurality of periodic transmission period candidates that can be set by the periodic transmission terminal 2 are stored in the periodic transmission period candidate storage unit 32, and each periodic transmission terminal 2 stores the plurality of periodic transmissions. From the period, a free regular transmission period that is not used by another regular transmission terminal 2 is extracted, and one of the extracted free regular transmission periods is selected as its own regular transmission period.

  For this reason, for example, a periodic transmission period used for periodic transmission by detecting a period that is not used as a periodic transmission period by another periodic transmission terminal 2 within one periodic transmission period. As compared with the case where the value is arbitrarily set, the periodic transmission period can be efficiently allocated.

  Further, in this case, when setting the candidates for the periodic transmission period stored in the periodical transmission period candidate storage unit 32, the random transmission terminal is set by not setting the candidates for the periodical transmission period for a certain period within one periodical transmission period. The random transmission period according to 4 can be secured.

  Further, in the regular transmission terminal 2 of the present embodiment, when the number of times C of transmission of the regular transmission information restored by the data receiving unit 18 is equal to or greater than a predetermined value “3”, the vacancy determination process A is not performed. Yes.

  This is because the periodic transmission information whose transfer count C is equal to or greater than the predetermined value “3” has been transferred via a plurality of (three in the present embodiment) random transmission terminals 4, and the transmission of the periodic transmission information is performed. This is because the distance between the original regular transmission terminal 2 and the regular transmission terminal 2 is long, and it is considered that the transmission radio waves from both terminals do not interfere with each other.

Therefore, according to the present embodiment, the periodical transmission information for performing the vacancy determination process A is limited to that with the transfer count C being less than the upper limit (0, 1, 2), so that the vacancy determination process A is unnecessary. It is possible to prevent the number of empty regular transmission periods that can be set as its regular transmission period from being reduced.
[Second Embodiment]
Next, FIG. 6 and FIG. 7 show the free regular transmission period setting process executed by the microcomputer in order to realize the function as the free regular transmission period determination unit 34 in the regular transmission terminal 2 of the second embodiment. It is a flowchart showing.

The configuration of the regular transmission terminal 2 of the second embodiment is the same as that of the first embodiment shown in FIG.
(Free periodic transmission period setting process)
As shown in FIG. 6, the idle regular transmission period setting process of the present embodiment is basically the same as that of the first embodiment shown in FIG. 4, and the difference from the first embodiment is S120. In step S132, it is determined whether or not the number of transfers C is “0”. If the number of transfers C is “0”, it is determined whether the number of times C is “0”. If the process A is executed and the transfer count C is not “0”, it is determined in S134 whether the transfer count C is “1” or “2”, and the transfer count C is “1” or “2”. If “2”, the process proceeds to S142, and a vacancy determination process B different from the vacancy determination process A is executed.

  That is, in the present embodiment, when the periodic transmission period information restored by the data receiving unit 18 is the periodic transmission period information (transfer count C = 0) transmitted directly from another periodic transmission terminal 2. The periodical transmission period information restored by the data receiving unit 18 after executing the vacancy determination process A is transferred once or twice by the random transmission terminal 4 (transfer count C = 1, 2). ), An empty determination process B is executed.

  Further, as shown in FIG. 7, this vacancy determination process B is basically the same as the vacancy determination process A shown in FIG. 5. The difference from the vacancy determination process A is the nth in S220. The counter for counting the number of “empty” determinations in the nth periodic transmission period in S222 when it is determined that the periodic transmission period is “free” different from the periodic transmission period of the periodic transmission information acquired this time m (n) is incremented, and in S230, it is determined whether or not the value of the counter m (n) exceeds the threshold value M1, and the value of the counter m (n) exceeds the threshold value M1. Sometimes, the process proceeds to S230, and if the value of the counter m (n) does not exceed the predetermined value, the process proceeds to S240.

  That is, in this vacancy determination process B, the N regular transmission periods stored as candidates for the regular transmission period are equal to or greater than a predetermined number of times corresponding to the threshold value M1 based on the regular transmission information received within the determination time T1. When it is determined as “free”, the regular transmission period is provisionally determined to be “free”.

  This is because, for example, in FIG. 1A, when the random transmission terminal 4a does not exist in the overlap area where the radio waves from the regular transmission terminals 2a and 2b reach, or the random transmission terminal 4b in the communication area of the regular transmission terminal 2b. When transmission of periodic transmission information from the random transmission terminal 4a to the periodic transmission terminal 2a is temporarily stopped, such as when communication failure occurs between the random transmission terminal 4a and the random transmission terminal 4a in the communication area of the periodic transmission terminal 2a This is to prevent erroneous extraction of the free periodic transmission period.

  That is, the periodic transmission information transferred from the random transmission terminal 4 is larger than the periodic transmission information directly transferred from the periodic transmission terminal 2, and the periodic transmission information of a plurality of periodic transmission terminals 2 is included in one reception data. May be included, so it is extremely effective for specifying an empty regular transmission period.

  However, when necessary periodic transmission information cannot be acquired from a specific random transmission terminal 4 as described above, an empty periodic transmission period is extracted only from the periodic transmission information transferred from other random transmission terminals 4. Therefore, a regular transmission period that should not be extracted as an empty regular transmission period may be erroneously extracted.

  Therefore, in this embodiment, when extracting the idle regular transmission period based on the regular transmission information transferred from the random transmission terminal 4, by executing the idle determination process B, a plurality of regular transmission periods are extracted based on the regular transmission information. The periodic transmission period determined to be “free” times is tentatively determined as an empty regular transmission period.

  As shown in FIG. 6, in the free regular transmission period setting process of this embodiment, the free determination processes A and B are executed in S140 and S142, or the transfer count C is set in S134. If it is determined that it is not “1” or “2”, the process proceeds to S150.

  In S160, it is determined whether or not at least one of the empty determination processes A and B has been executed. If it is determined in S160 that at least one of the empty determination processes A and B has been executed, the process proceeds to S170. Transition.

Then, in S170, the periodic transmission determined as “empty” for all the periodic transmission information subjected to the availability determination from the periodic transmission periods temporarily determined as “available” in each of the availability determination processes A and B. A period is extracted, and the extracted regular transmission period is stored in the regular free transmission period table 36 as a free regular transmission period that is not used by other regular transmission terminals 2.
(Effect of 2nd Embodiment)
Therefore, according to the regular transmission terminal 2 of the present embodiment, when the regular transmission period information necessary for setting the regular transmission period cannot be acquired from the random transmission terminal 4, the regular transmission period information is handled. It is possible to prevent the periodic transmission period from being extracted as an empty regular transmission period.

  Therefore, according to the regular transmission terminal 2 of the present embodiment, in addition to the same effects as those of the first embodiment, the regular transmission period of the other regular transmission terminal 2 is also set as the regular transmission period of the regular transmission terminal 2. There is an effect that the probability of erroneous setting can be reduced.

In this embodiment, the vacancy determination process A executed in S140 corresponds to the first extraction means of the present invention, and the vacancy determination process B executed in S142 is the second extraction means of the present invention. It corresponds to.
[Third Embodiment]
Next, FIG. 8 is a block diagram showing the configuration of the regular transmission terminal 2 of the third embodiment, and FIGS. 9 and 10 show the free regular transmission period determination unit 34 in the regular transmission terminal 2 of the third embodiment. 6 is a flowchart showing an empty regular transmission period setting process executed by a microcomputer to realize the function as
(Configuration of periodic sending terminal)
As shown in FIG. 8, the configuration of the regular transmission terminal 2 of the present embodiment is substantially the same as that of the first and second embodiments shown in FIG. 2, and is different from the first and second embodiments. The demodulation processing unit 16 is provided with a detection circuit (not shown) for detecting the signal level (reception level) of the received signal, and the detected reception level is input to the idle periodic transmission period determination unit 34. Is a point.
(Free periodic transmission period setting process)
Also, as shown in FIG. 10, the idle periodic transmission period setting process of the present embodiment is basically the same as that of the second embodiment shown in FIG. 6, and is different from the second embodiment. If it is determined in S132 that the transfer count C is not “0”, it is determined in S136 whether the transfer count C is “1”, and if the transfer count C is “1”. In S142, the space determination process B is executed. If the transfer count C is not "1", it is determined in S138 whether the transfer count C is "2", and the transfer count C is "2". If there is, the vacancy determination process C is executed in S144.

  That is, in the present embodiment, when the periodic transmission period information restored by the data receiving unit 18 is the periodic transmission period information (transfer count C = 0) transmitted directly from another periodic transmission terminal 2. When the periodical transmission period information restored by the data receiving unit 18 after executing the vacancy determination process A is the periodical transmission period information (transfer count C = 1) transferred once by the random transmission terminal 4 When the periodical transmission period information restored by the data reception unit 18 after executing the vacancy determination process B is the periodical transmission period information (transfer count C = 2) transferred twice by the random transmission terminal 4 In this case, an empty determination process C is executed.

  In addition, as shown in FIG. 10, this vacancy determination process C is basically the same as the vacancy determination process B shown in FIG. Immediately after the start, in S200, based on the reception level input from the demodulation processing unit 16, the reception level P of the received signal when the periodic transmission information acquired from the data reception unit 18 is received is detected, and the reception level is detected. It is determined whether or not P is larger than a preset threshold value Th1, and when the reception level P is larger than the threshold value Th1, the processes after S210 are executed, and the reception level P is equal to the threshold value Th1. In the following cases, the vacancy determination process C is terminated as it is.

  In other words, the periodic transmission information received / restored by the periodic transmission terminal 2 is considered to have a longer distance from the transmission source periodic transmission terminal 2 as the transfer count C is larger. Can be estimated from the reception level of the received signal including the periodical transmission information.

  Therefore, in the present embodiment, when the number of times C of transmission of the regular transmission information acquired from the data reception unit 18 is “2”, the reception level P of the reception signal including the regular transmission information is a threshold value. When it is larger than Th1, the distance from the random transmission terminal 4 that has transferred the periodic transmission information is short, and the transmission radio wave from the periodic transmission terminal 2 that is the transmission source of the periodic transmission information is If it is determined that radio interference may occur due to arrival in the communication area, the periodic transmission information acquired this time is used for extraction of an empty periodic transmission period, and the reception level P of the received signal is equal to or less than the threshold Th1. For example, it is determined that radio wave interference does not occur, and it is prohibited to use the periodical transmission information acquired this time for the extraction of the vacant periodical transmission period.

  As shown in FIG. 9, in the empty regular transmission period setting process of this embodiment, empty determination processes A, B, and C are executed in S140, S142, and S144, or in S138, If it is determined that the transfer count C is not “2”, the process proceeds to S150.

  In S160, it is determined whether or not at least one of the empty determination processes A, B, and C has been executed. In S160, it is determined that at least one of the empty determination processes A, B, and C has been executed. Then, the process proceeds to S170.

Then, in S170, it is determined as “empty” for all the periodic transmission information subjected to the availability determination from the periodic transmission periods temporarily determined as “available” in each of the availability determination processes A, B, and C. The regular transmission period is extracted, and the extracted regular transmission period is stored in the free regular transmission period table 36 as a free regular transmission period that is not used by other regular transmission terminals 2.
(Effect of the third embodiment)
Therefore, according to the periodic transmission terminal 2 of the present embodiment, the periodic transmission is performed using the transfer count C of the periodic transmission information restored by the data reception unit 18 and the reception level of the reception signal including the periodic transmission information. Periodic transmission information used for setting the period can be identified, and the periodical transmission period can be set more appropriately compared with the periodical transmission terminal 2 of the first and second embodiments.
[Fourth Embodiment]
Next, FIG. 11 is a block diagram showing the configuration of the regular transmission terminal 2 of the fourth embodiment, and FIGS. 12 to 14 show the idle regular transmission period determination unit 34 in the regular transmission terminal 2 of the fourth embodiment. 6 is a flowchart showing an empty regular transmission period setting process executed by a microcomputer to realize the function as
(Configuration of periodic sending terminal)
As shown in FIG. 11, the configuration of the regular transmission terminal 2 of the present embodiment is substantially the same as that of the third embodiment shown in FIG. 8. The difference from the third embodiment is that the regular transmission period setting unit The periodical transmission period information registered in the periodical transmission period table 20 via the periodical transmission period selection unit 38 is input to the idle periodical transmission period determination unit 34 of the periodical transmission period setting unit 30.
(Free periodic transmission period setting process)
In the idle regular transmission period setting process of this embodiment, as shown in FIG. 12, first, in S310, the regular transmission period is selected by the regular transmission period selection unit 38 (in other words, to the regular transmission period table 20). Whether or not the writing of the periodic transmission period of (1) is once completed.

  If the selection of the regular transmission period has not ended (in other words, if the regular transmission period is not written in the regular transmission period table 20), in S320, the first to third embodiments. The idle periodic transmission period setting process before selecting the regular transmission period is executed in the same procedure as any of the idle periodic transmission period setting processes.

  In addition, after performing the process of S320, although the regular transmission based on the regular transmission period information stored in the regular transmission period table 20 is started, the idle regular transmission period setting process of this embodiment is the start of the regular transmission. It is also periodically executed afterwards.

  Next, in S310, when it is determined that the selection of the periodic transmission period has been completed (in other words, when the periodic transmission period is written in the periodic transmission period table 20 and the periodic transmission is started). , The process proceeds to S330, and the idle regular transmission period determination process after the regular transmission period is selected is executed.

This idle periodic transmission period determination process is executed according to the procedure shown in FIG.
That is, in the free regular transmission period determination process, first, in S410, it is determined whether or not the data receiving unit 18 has received data including the regular transmission information.

  In S410, if the data reception unit 18 determines that the data including the regular transmission information is not received, the process proceeds to S460. Conversely, the data reception unit 18 receives the data including the regular transmission information. If it is determined that the process has been performed, the process proceeds to S420.

In S420, the transfer count C of the periodic transmission information is read from the data receiving unit 18, and it is determined whether or not the read transfer count C is a value “1”.
If the number of transfers C is not “1”, the process proceeds to S460. If the number of transfers C is “1”, the process proceeds to S440, and the vacancy determination process D is executed according to the procedure shown in FIG. .

  As shown in FIG. 14, in the vacancy determination processing D, first, in S510, it is determined whether or not the reception data restored by the data reception unit 18 includes periodic transmission information representing its own periodic transmission period. If the received data includes the periodic transmission information indicating its own periodic transmission period, the process proceeds to S520, and the own periodic transmission period is set to an unused periodic transmission period that is not used by other periodic transmission terminals 2. It is determined that there is, and the empty determination process D is terminated.

  If it is determined in S510 that the received data does not include the periodic transmission information indicating its own periodic transmission period, the process proceeds to S530 and based on the reception level input from the demodulation processing unit 16 Then, the reception level P of the received signal when the periodic transmission information acquired from the data receiving unit 18 is received is detected, and it is determined whether or not the reception level P is greater than a preset threshold value Th2.

If the reception level P is greater than the threshold value Th2, the process proceeds to S540. If the reception level P is equal to or less than the threshold value Th2, the process proceeds to S520.
In S540, the counter u for counting the number of times it is determined that the received data does not include its regular transmission period is incremented (+1). In S550, the value of the counter u is set in advance. It is determined whether or not the threshold value U1 has been exceeded.

  If the value of the counter u does not exceed the threshold value U1, the process proceeds to S520. If the value of the counter u exceeds the threshold value U1, the process proceeds to S560, and the previously set periodicity is set. During the transmission period, it is determined that another periodic transmission terminal 2 is in use, and the empty determination process D is terminated.

When the vacancy determination process D is executed in this way, the process proceeds to S450 in FIG. 13 and it is determined in the vacancy determination process D whether or not its regular transmission period is determined to be “vacant”. To do.
When it is determined in the idle determination process D that its regular transmission period is “vacant”, the process proceeds to S460, and the elapsed time t from the start of the regular idle transmission period setting process is determined in advance. It is determined whether or not the set determination time T2 (several times as long as one periodic transmission period) has been exceeded. If the elapsed time t does not exceed the determination time T2, the process proceeds to S410 again, and the above steps S410 to S450 are performed. Execute the process.

  On the other hand, in S460, it is determined that the elapsed time t has exceeded the determination time T2, or it is determined in the idle determination process D that the other periodic transmission terminal 2 is in use for its regular transmission period. If it is present (S450: NO), the determination result in the empty determination process D is held as the final determination result, and the empty regular transmission period determination process ends.

  When the free regular transmission period determination process (S330) after the regular transmission period is selected in this way, the process proceeds to S340 in FIG. 12, and the free regular transmission period determination process (S330) It is determined whether or not the transmission period is determined to be “free”.

If it is determined in the free regular transmission period determination process (S330) that the regular transmission period is “free”, it is determined that the regular transmission period stored in the regular transmission period table 20 is normal. If the periodical transmission period determination process (S330) determines that the other periodical transmission terminal 2 is in use, the periodical transmission period setting process ends (S330). In order to rewrite the periodic transmission period stored in the transmission period table 20, the process proceeds to an empty periodic transmission period setting process before selecting the periodic transmission period in S320.
(Effect of 4th Embodiment)
As described above, in this embodiment, the idle periodic transmission terminal setting process (S320) is executed by the same procedure as in any of the first to third embodiments, so that other periodic transmission terminals 2 use it. An unused periodic transmission period is extracted and one of them is stored in the periodic transmission period table 20 as its own periodic transmission period, and the periodic transmission period is used by other periodic transmission terminals 2. In order to confirm whether there is no periodic transmission period determination process (S330).

  In this periodic transmission period determination process (S330), the periodic transmission information transmitted from the periodic transmission terminal 2 by regular transmission is received by the surrounding random transmission terminals 4, and the regular transmission information is transmitted from the random transmission terminal 4 to the regular transmission period. By determining whether or not the transmission information has been transferred as periodic transmission information with the transfer count C = 1, it is confirmed that its own periodic transmission information has been transferred, and received data from the surrounding random transmission terminals 4 If the number of times that its own periodic transmission information is not included (the value of the counter u) exceeds the threshold value U1, its own periodic transmission period coincides with the periodic transmission period of the other periodic transmission terminal 2, and the transmitted radio wave Therefore, the idle periodic transmission period setting process (320) is executed again.

  Therefore, according to the regular transmission terminal 2 of the present embodiment, the same regular transmission period as the other regular transmission terminals 2 is set as its regular transmission period by the idle regular transmission period setting process (S320) before the regular transmission period is selected. When an erroneous setting is made, this fact can be detected promptly, and its own periodic transmission period can be reset to a periodic transmission period that is not used by other periodic transmission terminals 2.

  Therefore, according to the regular transmission terminal 2 of the present embodiment, it is possible to more reliably prevent the occurrence of radio wave interference with the other regular transmission terminals 2 as compared with the first to third embodiments. It is possible to suppress the occurrence of communication failure in the random transmission terminal 4 due to the radio wave interference generated with the other regular transmission terminals 2.

In the present embodiment, the processes of S330 and S340 correspond to the periodic transmission determination unit of the present invention.
[Modification]
As mentioned above, although 1st Embodiment-4th Embodiment was described as embodiment of this invention, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it is various. It can take the form.

  For example, in the above-described embodiment, the periodic transmission terminal 2 as the first communication device has been described as being installed in the vicinity of the traveling path of the automobile as a roadside device. You may make it mount in the vehicle which needs to notify important information preferentially to the surrounding general vehicle.

  Further, in the above embodiment, in the periodic transmission terminal 2, the periodic transmission information acquired from the random transmission terminal 4 in which the transfer count C is equal to or greater than a predetermined value is not used for setting its own periodic transmission period. However, for example, in a wireless communication system in which the transfer count C is not given to the periodic transmission information transferred from the random transmission terminal 4, the reception level of the received signal including the periodic transmission information is equal to or higher than the threshold value. Only the transmission information may be used for setting its own periodic transmission period.

  In the above embodiment, the transfer number information given to the periodic transmission information has been described as being updated by incrementing (+1) when each random transmission terminal 4 retransmits the periodic transmission information. For example, each random transmission terminal 4 may be configured to be updated by decrementing (-1) when retransmitting the periodic transmission information.

  2, 2a, 2b ... periodic transmission terminals, 4, 4a, 4b ... random transmission terminals, 12 ... data transmission unit, 14 ... modulation processing unit, 16 ... demodulation processing unit, 18 ... data reception unit, 20 ... regular transmission period table , 22: Periodic transmission period determination unit, 24: Periodic transmission information generation unit, 26: Clock, 30: Periodic transmission period setting unit, 32: Periodic transmission period candidate storage unit, 34: Free regular transmission period determination unit, 36: Free Periodic transmission period table, 38... Periodic transmission period selection part, 40... Periodic transmission period table, 42... Periodic transmission period update part, 44 ... Random transmission prohibition period determination part, 50.

Claims (7)

Using a predetermined communication channel, it has a periodic transmission function for performing wireless transmission within a predetermined periodic transmission period shorter than the predetermined period at a preset fixed period. A plurality of first communication devices configured to transmit data including periodic transmission period information representing;
A plurality of second communication devices having a random transmission function for determining whether or not the communication channel is free when a transmission request occurs and performing wireless transmission when the communication channel is free;
The two types of communication devices
When each of the second communication devices receives a signal including the periodic transmission period information from the first communication device or another second communication device, the periodic transmission period information is restored from the received signal and the periodic transmission is performed. Limiting its own transmission period so as not to carry out random transmission within the periodical transmission period corresponding to the period information, and using the communication channel, the restored periodical transmission period information is transferred to other communication devices. In a wireless communication system configured to transfer,
A wireless communication device used as the first communication device,
Receiving means for receiving a transmission signal transmitted from the second communication device and another first communication device using the communication channel, and restoring received data;
The periodic transmission period information is extracted from the reception data restored by the receiving means, and based on the extracted periodic transmission period information, a periodic transmission period in which the wireless communication apparatus performs periodic transmission is set as another first transmission period. Periodic transmission period setting means for setting so as not to overlap with the periodic transmission period of the communication device;
With
The periodic transmission period setting means includes:
Based on the periodic transmission period information, a free periodic transmission period extracting unit that extracts a free periodic transmission period that is not used by another first communication device from a plurality of periodic transmission periods stored in advance;
Periodic transmission period selection means for selecting a periodic transmission period in which the wireless communication device performs periodic transmission from among the idle periodic transmission periods extracted by the idle transmission period extraction means;
With
The empty regular transmission period extraction means includes:
First extraction means for extracting the idle periodic transmission period based on the periodic transmission period information included in the received data from the other first communication device;
Based on the periodic transmission period information included in the received data from the second communication device, a periodic transmission period determined to be not used by another first communication device for a predetermined number of times or more Second extraction means for extracting as a period;
With
The periodical transmission period selecting means is a periodical transmission period in which the wireless communication device performs periodical transmission from among the periodical idle transmission periods extracted as the periodical idle transmission periods by both the first extraction means and the second extraction means. radio communication apparatus characterized by selecting. Using a predetermined communication channel, it has a periodic transmission function for performing wireless transmission within a predetermined periodic transmission period shorter than the predetermined period at a preset fixed period. A plurality of first communication devices configured to transmit data including periodic transmission period information representing;
A plurality of second communication devices having a random transmission function for determining whether or not the communication channel is free when a transmission request occurs and performing wireless transmission when the communication channel is free;
The two types of communication devices
When each of the second communication devices receives a signal including the periodic transmission period information from the first communication device or another second communication device, the periodic transmission period information is restored from the received signal and the periodic transmission is performed. Limiting its own transmission period so as not to carry out random transmission within the periodical transmission period corresponding to the period information, and using the communication channel, the restored periodical transmission period information is transferred to other communication devices. In a wireless communication system configured to transfer,
A wireless communication device used as the first communication device,
Receiving means for receiving a transmission signal transmitted from the second communication device and another first communication device using the communication channel, and restoring received data;
The periodic transmission period information is extracted from the reception data restored by the receiving means, and based on the extracted periodic transmission period information, a periodic transmission period in which the wireless communication apparatus performs periodic transmission is set as another first transmission period. Periodic transmission period setting means for setting so as not to overlap with the periodic transmission period of the communication device;
With
When the plurality of second communication devices constituting the wireless communication system transfer the periodic transmission period information restored from the received signal, the second communication apparatuses transmit the periodic transmission period information from the first communication device. 2 is configured to give transfer count information indicating the transfer count transferred by the communication device,
The periodic transmission period setting means detects the number of times of transfer of the periodic transmission period information based on the number of times of transfer given to the periodic transmission period information extracted from the received data, and the upper limit of the number of times of transfer set in advance The wireless communication apparatus, wherein the periodic transmission period information equal to or greater than the value is excluded from the periodic transmission period information used for setting the periodic transmission period of the wireless communication apparatus. The periodic transmission period setting means includes:
Based on the periodic transmission period information, a free periodic transmission period extracting unit that extracts a free periodic transmission period that is not used by another first communication device from a plurality of periodic transmission periods stored in advance;
Periodic transmission period selection means for selecting a periodic transmission period in which the wireless communication device performs periodic transmission from among the idle periodic transmission periods extracted by the idle transmission period extraction means;
The wireless communication apparatus according to claim 2 , further comprising: The empty regular transmission period extraction means includes:
First extraction means for extracting the idle periodic transmission period based on the periodic transmission period information included in the received data from the other first communication device;
Based on the periodic transmission period information included in the received data from the second communication device, a periodic transmission period determined to be not used by another first communication device for a predetermined number of times or more Second extraction means for extracting as a period;
And the periodic communication period selecting means performs periodic transmission by the wireless communication apparatus from among the vacant regular transmission periods extracted as vacant regular transmission periods by both the first extracting means and the second extracting means. The wireless communication apparatus according to claim 3 , wherein a periodic transmission period is selected.   The periodic transmission period setting means determines whether or not the reception level of the reception data has reached a predetermined determination level, and for the periodic transmission period information of reception data whose reception level has not reached the determination level, The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus is excluded from periodic transmission period information used for setting a periodic transmission period of the wireless communication apparatus. When the periodical transmission period is set by the periodical transmission period setting means and the wireless communication apparatus starts the periodical transmission within the periodical transmission period, then the periodical transmission period of the radio communication apparatus from the second communication apparatus It is determined whether or not data including information can be received, and when the data including the periodical transmission period information of the wireless communication apparatus cannot be received from the second communication apparatus, the periodical transmission period is reset to the periodical transmission period setting unit. Periodic transmission judgment means to be set,
The wireless communication apparatus according to any one of claims 1 to 5, further comprising: Using a predetermined communication channel, it has a periodic transmission function for performing wireless transmission within a predetermined periodic transmission period shorter than the predetermined period at a preset fixed period. A plurality of first communication devices configured to transmit data including periodic transmission period information representing;
A plurality of second communication devices having a random transmission function for determining whether or not the communication channel is free when a transmission request occurs and performing wireless transmission when the communication channel is free;
The two types of communication devices
When each of the second communication devices receives a signal including the periodic transmission period information from the first communication device or another second communication device, the periodic transmission period information is restored from the received signal and the periodic transmission is performed. Limiting its own transmission period so as not to carry out random transmission within the periodical transmission period corresponding to the period information, and using the communication channel, the restored periodical transmission period information is transferred to other communication devices. In a wireless communication system configured to transfer,
The wireless communication system, wherein each of the plurality of first communication devices is configured by the wireless communication device according to any one of claims 1 to 6.

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