JP2008177791A - Radio transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a delay time of information transmission while reducing the power consumption of a radio device. <P>SOLUTION: If the reception of a radio signal is failed owing to the occurrence of a transmission error, a control unit 1 checks a radio wave again, sets an intermittent reception interval to the same time with a pause period when a radio wave cannot be acquired, and starts counting the intermittent reception interval by a timer. Since timing where the counting of the intermittent reception interval set to the same time with the pause period is completed always matches a next transmission period, a time up to a time when the radio signal can be received normally, i.e. a delay time of the information transmission can be made shorter than that when the intermittent reception interval is not varied to the same time with the pause period. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless transmission system for transmitting a wireless signal between a plurality of wireless devices.

  For radio equipment used in Japan, the characteristics of radio waves used (RF characteristics) such as occupied frequency bandwidth and adjacent channel leakage power must satisfy the regulations of the Radio Law. In the Radio Law, different standards (communication standards) are defined for each purpose of use. For example, the “specified low-power radio station” defined in Article 6 of the Radio Law Enforcement Regulations uses a telemeter for automatically displaying or recording the measurement results of remote measuring devices using radio waves. , For telecontrol that transmits signals for the purpose of starting, changing or terminating the function of a device at a remote point using radio waves, and transmission of information processed mainly by machines or transmission of processed information "Specified low-power radio station telemeter, telecontrol and data transmission radio equipment standard (Radio Industry Association Standard ARIB STD-T67)" or mainly fire "Small power," which is defined for the wireless facilities of the low power security system that reports theft or other abnormalities or controls associated therewith Curie tee system of the radio station radio equipment standards (Association of Radio Industries and Businesses Standard RCR STD-30) ", and the like.

  On the other hand, as a radio transmission system provided with the specific low-power radio station, there is a fire alarm system described in Patent Document 1, for example. Such a fire alarm system has a function in which a plurality of fire detectors (radio units) installed in many places sense a fire and sound a warning sound. When a fire is detected, the fire detector sounds an alarm sound and transmits information (fire detection information) to notify the fire detection to other fire detectors by wireless signals, so that not only the fire source fire detector. A plurality of fire detectors interlock and sound an alarm sound all at once, so that the occurrence of a fire can be notified quickly and reliably.

Such a fire detector (wireless device) is driven by a battery in order to take advantage of the characteristic of transmitting fire detection information with a radio signal, and is usually used for maintenance (battery replacement) like an indoor ceiling. Since it is installed in a difficult place, it is desirable that it can be used without maintenance for a long period of time such as several years. Therefore, each fire detector intermittently activates a receiving circuit to check whether or not a desired radio wave (a radio signal transmitted by another fire sensor) can be received. It is desired to significantly reduce the average power consumption by stopping the receiving circuit and shifting to the standby state.
JP 2006-343983 A

  By the way, in the above-mentioned standard for the specific low-power radio station, the period (transmission period) during which radio waves can be continuously transmitted from the radio station (radio unit) and the period during which radio waves should not be transmitted (pause period) are specified. Therefore, a wireless signal cannot be received unless the timing of intermittent reception matches the transmission period. In addition, during the transmission period, a radio signal having a data format including at least a synchronization bit, a frame synchronization pattern, a message, and a CRC code as one frame is continuously transmitted for several frames. Even if the synchronization is possible, the specification shifts to a suspension period when a message error or CRC error occurs. If a reception error occurs in this way, the radio wave check is not performed unless a certain time (intermittent reception interval) has passed again, and the timing for receiving a radio signal is delayed.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wireless transmission system capable of reducing the delay time of information transmission while reducing the power consumption of the wireless device.

  In order to achieve the above object, a first aspect of the present invention is a wireless transmission system including a plurality of wireless devices and transmitting wireless signals between the plurality of wireless devices, wherein each wireless device transmits a wireless signal. At least one of transmitting means for transmitting or receiving means for receiving a radio signal and a battery for supplying power are commonly provided, and the wireless device including the transmitting means transmits when a predetermined event occurs. And a transmission control means for stopping the transmission means when the event does not occur and alternately repeating the operation of transmitting a radio signal during a predetermined transmission period and stopping the transmission of the radio signal during a predetermined pause period. A radio unit equipped with a receiving means, a timer means for repeatedly counting a constant intermittent reception interval, and the reception means is stopped during the counting of the intermittent reception interval by the timer means And receiving control means that activates the receiving means every time counting of the intermittent reception interval by the timer means is completed, the receiving control means receives a radio signal when a desired radio wave is captured by the receiving means, If the desired radio wave is not captured, the receiving means is stopped, and if reception of the radio signal fails again, if the desired radio wave is captured again by the receiving means, the reception means is continued without stopping, If radio waves are not captured, the intermittent reception interval is set to a time equal to the pause period, and the counting of the intermittent reception interval by the timer means is resumed.

  According to a second aspect of the present invention, in the first aspect of the invention, the data format of the radio signal includes at least a synchronization bit, a frame synchronization pattern, a destination address, a transmission source address, and a message. Every time the reception interval count is completed, the frame time corresponding to one frame of the radio signal is started, and when the frame time count is completed, the intermittent reception interval is started again. If the frame synchronization is not achieved by the frame synchronization pattern while the timer means is counting the frame time, and the radio wave is not captured when the frame time count is completed, the intermittent reception interval is set to a time equal to the pause period. The counting of the intermittent reception interval by the means is restarted.

  According to a third aspect of the present invention, in the first aspect of the invention, the data format of the radio signal includes at least a synchronization bit, a frame synchronization pattern, a destination address, a source address, and a message. Every time the reception interval count is completed, the frame time corresponding to one frame of the radio signal is started, and when the frame time count is completed, the intermittent reception interval is started again. While the timer means counts the frame time, it always monitors whether or not the radio wave is captured, and when the timer means stops counting the frame time, the intermittent reception interval is equal to the pause period. It is characterized in that the counting of the intermittent reception interval by the timer means is restarted by setting the time.

  According to the first aspect of the present invention, when reception of a radio signal fails, if a desired radio wave is not captured again by the receiving means, it is estimated that the transmitting-side radio has entered a pause period, and the intermittent reception interval is paused. By setting the time equal to the period to resume counting of the intermittent reception interval by the timer means, the reception means finishes counting the intermittent reception interval at the start of the next transmission period or immediately after the start, and receives the radio signal by the reception means As a result, it is possible to shorten the time until the wireless signal can be normally received, that is, the delay time of information transmission, while reducing the power consumption of the wireless device.

  According to the second and third aspects of the present invention, it is possible to determine at a relatively early stage whether or not reception of a radio signal has failed, and wasteful power consumption can be suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a system configuration diagram of the present embodiment, and a radio transmission system is configured by a plurality of radio units TR (only two units are illustrated). In the following description, when the radio units TR are individually indicated, they are indicated as radio units TR1, TR2,..., TRn, and when collectively indicated, they are indicated as radio units TR.

  The radio TR transmits a radio signal using radio waves as a medium from the antenna 3 and receives a radio signal transmitted from another radio TR by the antenna 3, and an event generator having a microcomputer as a main component. When the occurrence of an event is notified from 4, the control unit 1 for transmitting a radio signal including a notification message from the radio transmission / reception unit 2 in order to notify the other radio unit TR of the occurrence of the event, and when the event occurs An event generation unit 4 for notifying the occurrence of an event to the control unit 1, a notification unit 5 for notifying that the event generation unit 4 has notified the occurrence of the event to the control unit 1, and a battery such as a dry battery as a power source And a battery power supply unit 6 for supplying operating power to each unit. Each wireless device TR1, TR2,... Is assigned a unique identification code, and the destination of the wireless signal and the transmitting wireless devices TR1, TR2,.

  The radio transmission / reception unit 2 transmits / receives a radio signal using radio waves as a medium in accordance with “specific low-power radio stations” defined in Article 6 of the Radio Law Enforcement Regulations. Further, the event generation unit 4 detects suspiciously by detecting fire detection means for detecting a fire by detecting smoke, heat, flame, etc. generated by a fire or detecting a heat ray (infrared ray) emitted from a human body. Security anomaly detecting means for detecting an anomaly related to security such as an intruder, an operation input accepting means for accepting an operation input such as a push button switch. However, the fire detection means, the security abnormality detection means, and the operation input reception means are well known in the art and will not be described in detail.

  The control unit 1 realizes various functions to be described later by executing a program stored in the memory with a microcomputer. For example, when the event generation unit 4 has a fire detection means, when the event generation unit 4 notifies that the fire has been detected, the control unit 1 drives a buzzer included in the notification unit 5 to generate a notification sound. A radio that includes a notification message for notifying the occurrence of a fire in order to sound a notification of the occurrence of a fire in other radio units (fire detectors) TR as well as notifying the occurrence of a fire by sounding an (alarm sound) The signal is transmitted from the wireless transmission / reception unit 2. In addition, when the wireless transmission / reception unit 2 receives a wireless signal transmitted from another wireless device TR (a wireless signal including a notification message for notifying the occurrence of a fire), the control unit 1 uses a buzzer included in the notification unit 5. Drive to sound an alarm sound. That is, in the control unit 1, when the event generation unit 4 is notified of the occurrence of an event such as fire detection, human body detection, operation input reception, etc., the notification unit 5 generates a notification sound and notifies the occurrence of the event. The wireless transmission / reception unit 2 has a function of transmitting a wireless signal including a notification message.

  Here, as described in the related art, “Standard Equipment for Specific Low Power Radio Station Telemeter, Telecontrol and Data Transmission (Radio Industry Association Standard ARIB STD-T67)” and “Low Power Security” In the radio equipment standard of the system radio station (Radio Industry Association Standard RCR STD-30) etc., the period during which radio signals may be transmitted continuously (transmission period), the transmission period and the transmission period A period (pause period) between which radio signals should not be transmitted is defined. For example, the standard ARIB STD-T67 specifies a transmission period of 40 seconds or less and a pause period of 2 seconds or more, and the standard RCR STD-30 specifies a transmission period of 3 seconds or less and a pause period of 2 seconds or more. In addition, the control unit 1 transmits radio signals in a transmission period and a pause period that conform to these standards.

  Further, in order to extend the battery life of the battery power supply unit 6 as much as possible, the control unit 1 repeatedly counts a predetermined time interval (intermittent reception interval) with a timer (timer means) built in the microcomputer and completes counting of the intermittent reception interval. Each time, the wireless transceiver 2 is activated to check whether or not a desired radio wave (a radio signal transmitted by another radio device TR) can be received. If the radio wave is not detected, the radio transceiver 2 is immediately stopped. The average power consumption is greatly reduced by shifting to the standby state. The radio wave reception check is performed based on the received signal strength indication signal (Receiving Signal Strength Indication: RSSI signal) output from the wireless transmission / reception unit 2 and is a DC voltage signal proportional to the magnitude of the received signal strength. Specifically, if the received signal strength exceeds the specified value, it is judged that “the radio wave is captured”, and if the received signal strength is less than the specified value, “the radio wave is not captured”. "

  Further, the control unit 1 of a specific radio TR1 periodically activates the radio transmission / reception unit 2 to check whether the other radios TR2, TR3,. Transmits a radio signal including a confirmation message, receives the radio signal including a response message transmitted from each of the radio devices TR2,... And transmits the radio signal including the confirmation message. If there is a wireless device TR that does not transmit a wireless signal including a response message within a predetermined time, the wireless device TR is abnormal (battery) by driving a buzzer provided in the notification unit 5 to sound a notification sound. It also has a function of notifying that a break has occurred. That is, in the present embodiment, the control unit 1 corresponds to a transmission control unit and a reception control unit.

  FIG. 2A shows a data format of a radio signal transmitted / received by the radio equipment TR, and includes a synchronization bit (preamble: PA), a frame synchronization pattern (unique word: UW), a destination address DA, a source address SA, and a message. One frame is composed of M and CRC codes. Here, if the identification code of each wireless device TR is set as the destination address DA, only the wireless device TR of the identification code receives a radio signal and acquires a message. By setting a special bit string (for example, a bit string in which all bits are set to 1) that is not assigned to the TR, the radio signal can be broadcast (broadcast) and all the radio devices TR can acquire the message. . For example, a radio signal including a notification message for notifying the occurrence of an event such as a fire is broadcast to all the radio devices TR. Note that the control unit 1 causes the radio transmission / reception unit 2 to continuously transmit one frame of radio signals by the number that can be transmitted within one transmission period (see FIG. 2B).

  Next, the reception operation of this embodiment will be described with reference to the flowchart of FIG.

  The control unit 1 repeatedly counts the intermittent reception interval by a timer (not shown), and activates the wireless transmission / reception unit 2 to execute a radio wave check using an RSSI signal every time the intermittent reception interval elapses. When the radio wave is detected by the radio wave check, the control unit 1 starts the reception operation by the radio transmission / reception unit 2 and receives the synchronization bit PA and the frame synchronization pattern UW within a predetermined time (a time corresponding to one frame). Subsequently, the reception operation is continued, and when synchronization is not achieved within a predetermined time or when radio waves are not captured by radio wave check, the wireless transmission / reception unit 2 is stopped and the intermittent reception interval count is restarted.

  When synchronization is established, the control unit 1 determines whether the destination address DA of the received wireless signal matches a special bit string for broadcast (for example, all bits are 1) or its own identification code. To do. Here, a notification message for notifying the occurrence of an event such as the occurrence of a fire or a confirmation message for confirming the life or death is broadcast to all the radio devices TR by setting the special bit string in the destination address DA. For a radio signal transmitted only to a specific radio device TR such as a response message to a notification message or a confirmation message, the identification code of the radio device TR is set as the destination address DA. Accordingly, the control unit 1 receives the message M when it is determined to be broadcast or addressed to itself by the destination address DA, but stops the wireless transmission / reception unit 2 if it is determined not to be broadcast or addressed to itself by the destination address DA. To restart counting intermittent reception intervals.

  Further, the control unit 1 performs a transmission error check using a CRC code, and if there is no transmission error and the signal can be normally received, processing according to the content of the received message M, for example, generating a notification sound from the notification unit 5 to generate an event ( Notification of fire). On the other hand, when a transmission error occurs and reception of a radio signal fails, the control unit 1 performs radio wave check again. At this time, if the radio wave is captured, the control unit 1 continues the reception operation without stopping the wireless transmission / reception unit 2, and if the radio wave is not captured, the control unit 1 sets the intermittent reception interval to the same time as the pause period. Set to start counting the intermittent reception interval by the timer.

  Here, when the intermittent reception interval count is completed just before the end of the transmission period, it should normally be able to receive a radio signal in the next frame following the frame in which the radio wave check has been performed. If reception of the signal fails, it can only be received when the intermittent reception interval count is completed again, and if the next intermittent reception interval count completion timing does not coincide with the transmission period, reception of the radio signal is further delayed. It will end up. On the other hand, in this embodiment, when the reception of the radio signal fails as described above, the control unit 1 performs the radio wave check again, and immediately after switching from the transmission period to the suspension period if the radio wave is not captured. Since the intermittent reception interval is set to the same time as the pause period and counting of the intermittent reception interval by the timer is started, as long as the transmitter-side radio TR is transmitting a radio signal, the same time as the pause period is set. The timing at which the counting of the intermittent reception interval set in is completed must coincide with the next transmission period. As a result, compared with the case where the intermittent reception interval is not changed to the same time as the pause period, the time until the wireless signal can be normally received, that is, the information transmission delay time can be shortened.

(Embodiment 2)
Since the system configuration of this embodiment is the same as that of the first embodiment, the same components are denoted by the same reference numerals, and illustration and description thereof are omitted.

  In the first embodiment, the success or failure of radio signal reception is determined by a transmission error check using a CRC code. When frame synchronization by the frame synchronization pattern UW cannot be achieved, the control unit 1 immediately stops the radio transmission / reception unit 2 and performs intermittent reception. The interval count is restarted. On the other hand, in this embodiment, the success or failure of radio signal reception is determined based on whether or not frame synchronization can be achieved within a frame time corresponding to one frame, and the success or failure of radio signal reception is earlier than in the first embodiment. It is characterized in that wasteful power consumption is suppressed by judging the above.

  Hereinafter, the reception operation, which is a feature of this embodiment, will be described with reference to the flowchart of FIG.

  When the counting of the intermittent reception interval by the timer is completed, the control unit 1 starts counting the frame time corresponding to one frame and then activates the wireless transmission / reception unit 2 to execute the radio wave check using the RSSI signal. If radio waves are captured by the radio transmission / reception unit 2, the reception operation by the wireless transmission / reception unit 2 is started. If radio waves are not captured, the radio transmission / reception unit 2 is stopped and counting of intermittent reception intervals is restarted. Then, the control unit 1 continues to count the frame time by the timer until the frame synchronization is established after receiving the frame synchronization pattern UW. If the frame synchronization is established, the destination address DA of the radio signal received subsequently is used for broadcasting. It is determined whether or not it matches a special bit string or its own identification code, and if it is determined that it is broadcast or addressed to itself by the destination address DA, the message M is subsequently received. If it is determined that it is not, the wireless transmission / reception unit 2 is stopped and the intermittent reception interval counting is restarted.

  Further, the control unit 1 performs a transmission error check using a CRC code, and if there is no transmission error and the signal can be normally received, processing according to the content of the received message M, for example, generating a notification sound from the notification unit 5 to generate an event ( Notification of fire). On the other hand, when a transmission error occurs and reception of a radio signal fails, the control unit 1 performs a radio wave check again after starting counting the frame time from the beginning. At this time, if the radio wave is captured, the control unit 1 continues the reception operation without stopping the wireless transmission / reception unit 2, and if the radio wave is not captured, the control unit 1 stops the radio transmission / reception unit 2 and performs intermittent reception. Restart interval counting.

  On the other hand, when the counting of the frame time is completed before the frame synchronization is established, the control unit 1 checks the radio wave again. If the radio wave is detected, the control unit 1 continues the reception operation without stopping the wireless transmission / reception unit 2, and the radio wave is If not, the intermittent reception interval is set to the same time as the pause period, and counting of the intermittent reception interval by the timer is started.

  As described above, according to this embodiment, whether or not radio signal reception is successful is determined based on whether or not frame synchronization is achieved within a frame time corresponding to one frame. It is possible to suppress wasteful power consumption by determining the success or failure of signal reception.

(Embodiment 3)
Since the system configuration of this embodiment is the same as that of the first embodiment, the same components are denoted by the same reference numerals, and illustration and description thereof are omitted.

  Similarly to the second embodiment, the present embodiment also determines whether or not radio signal reception has succeeded based on whether or not frame synchronization can be achieved within a frame time corresponding to one frame. It is characterized in that wasteful power consumption is suppressed by determining the success or failure.

  Hereinafter, the reception operation, which is a feature of this embodiment, will be described with reference to the flowchart of FIG.

  When the counting of the intermittent reception interval by the timer is completed, the control unit 1 starts counting the frame time corresponding to one frame and then activates the wireless transmission / reception unit 2 to execute the radio wave check using the RSSI signal. If radio waves are captured by the radio transmission / reception unit 2, the reception operation by the wireless transmission / reception unit 2 is started. If radio waves are not captured, the radio transmission / reception unit 2 is stopped and counting of intermittent reception intervals is restarted. The control unit 1 counts the frame time using a timer while repeating the radio wave check at a 1-byte period until the frame synchronization is obtained after receiving the frame synchronization pattern UW. It is determined whether or not the destination address DA of the wireless signal matches a special bit string for broadcast or its own identification code. If it is determined that the destination address DA is broadcast or addressed to itself, the message M is subsequently received. However, if it is determined by the destination address DA that it is not addressed to the broadcast and itself, the wireless transmission / reception unit 2 is stopped and counting of the intermittent reception interval is restarted.

  Further, the control unit 1 performs a transmission error check using a CRC code, and if there is no transmission error and the signal can be normally received, processing according to the content of the received message M, for example, generating a notification sound from the notification unit 5 to generate an event ( Notification of fire). On the other hand, when a transmission error occurs and reception of a radio signal fails, the control unit 1 performs a radio wave check again after starting counting the frame time from the beginning. At this time, if the radio wave is captured, the control unit 1 continues the reception operation without stopping the wireless transmission / reception unit 2, and if the radio wave is not captured, the control unit 1 stops the radio transmission / reception unit 2 and performs intermittent reception. Restart interval counting.

  On the other hand, if the radio wave is not captured by the radio wave check during the frame time count, the control unit 1 sets the intermittent reception interval to the same time as the pause period and starts counting the intermittent reception interval by the timer. When the frame time count is completed before the frame synchronization is established, the control unit 1 stops the wireless transmission / reception unit 2 and restarts the intermittent reception interval count without setting the same time as the pause period.

  As described above, according to this embodiment, whether or not radio signal reception is successful is determined based on whether or not frame synchronization is achieved within a frame time corresponding to one frame. It is possible to suppress wasteful power consumption by determining the success or failure of signal reception. In addition, in the second embodiment, the radio wave check is performed again when the frame time count is completed, whereas in the present embodiment, the radio wave check is repeated periodically until the frame synchronization is obtained. Compared to the second embodiment, there is an advantage that the switching from the transmission period to the suspension period can be determined earlier.

It is a system configuration figure showing Embodiments 1-3 of the present invention. (A) is the data format of the radio signal in the above, and (b) is a time chart at the time of transmission. It is a flowchart for operation | movement description same as the above. It is a flowchart for operation | movement description of Embodiment 2 of this invention. It is a flowchart for operation | movement description of Embodiment 3 of this invention.

Explanation of symbols

1 Control unit (transmission control means, reception control means)
2 Radio transceiver (transmitting means, receiving means)
4 Event generation part 5 Notification part 6 Battery power supply part

Claims (3)

A wireless transmission system comprising a plurality of wireless devices and transmitting wireless signals between the plurality of wireless devices,
Each radio unit includes at least one of a transmission unit that transmits a radio signal or a reception unit that receives a radio signal, and a battery for power supply in common.
The wireless device including the transmission unit activates the transmission unit when a predetermined event occurs, and alternately performs an operation of transmitting a radio signal during a predetermined transmission period and halting transmission of the radio signal during a predetermined pause period. Repetitively and comprising a transmission control means for stopping the transmission means when the event has not occurred,
The wireless device having the receiving means stops the receiving means during the counting of the intermittent reception interval by the timer means that repeatedly counts a certain intermittent reception interval, and completes the counting of the intermittent reception interval by the timer means. And receiving control means for starting the receiving means,
The reception control means receives a radio signal when a desired radio wave is captured by the reception means, stops the reception means if the desired radio wave is not captured, and re-enters the reception means when reception of the radio signal fails. If the desired radio wave is captured, the reception operation is continued without stopping the reception means. A wireless transmission system that is restarted. The data format of the radio signal includes at least a synchronization bit, a frame synchronization pattern, a destination address, a source address, and a message,
The timer means starts counting the frame time corresponding to one frame of the radio signal each time counting of the intermittent reception interval is completed, and starts counting the intermittent reception interval again when the counting of the frame time is completed,
The reception control means sets the intermittent reception interval to a time equal to the pause period if the frame means cannot synchronize with the frame synchronization pattern while the timer means is counting the frame time, and the radio wave is not captured when the frame time count is completed. 2. The wireless transmission system according to claim 1, wherein the counting of the intermittent reception interval by the timer means is resumed. The data format of the radio signal includes at least a synchronization bit, a frame synchronization pattern, a destination address, a source address, and a message,
The timer means starts counting the frame time corresponding to one frame of the radio signal each time counting of the intermittent reception interval is completed, and starts counting the intermittent reception interval again when the counting of the frame time is completed,
The reception control means constantly monitors whether the radio wave is captured while the timer means is counting the frame time, and if the radio wave is not captured while the timer means is counting the frame time, the intermittent reception interval 2. The wireless transmission system according to claim 1, wherein the count of the intermittent reception interval by the timer means is restarted by setting the time equal to the pause period.

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