JP2008177793A - 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: A control unit 1 adds an end code FE to only the end of a frame Fm transmitted last in each transmission period. If the reception of a radio signal is failed, the control unit 1 considers that a transmission period changes to a pause period when detecting the end code FE, and sets an intermittent reception interval to the same time with a pause period, and makes a timer count the intermittent reception interval. Consequently, 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) 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 repeatedly transmitting the radio signal during a predetermined transmission period and stopping the transmission of the radio signal during a predetermined pause period, and stopping the transmission means when the event has not occurred. The radio having a receiving means includes a timer means for repeatedly counting a certain intermittent reception interval, and the receiving means is stopped during the counting of the intermittent reception interval by the timer means. And a reception control unit that activates the reception unit each time counting of the intermittent reception interval by the timer unit is completed, and the transmission control unit assigns a predetermined end code indicating the end of the transmission period to the last frame in the transmission period. The reception control means receives the radio signal when a desired radio wave is captured by the reception means, and stops the reception means if the desired radio wave is not captured, and further wirelessly If the end code is detected when signal reception has failed, the intermittent reception interval is changed to a time equal to the pause period to restart counting of the intermittent reception interval by the timer means. If the end code is not detected, the intermittent code is intermittent. The counting is restarted without changing the reception interval.

  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. An end code composed of the same bit string as the frame synchronization pattern is added to the end of the last frame in the transmission period and transmitted from the transmission means.

  According to the first aspect of the present invention, even if reception of a radio signal has failed, if a predetermined end code indicating the end of the transmission period is detected, it is estimated that the transmitting-side radio has entered a pause period Then, by setting the intermittent reception interval to a time equal to the pause period and restarting the counting of the intermittent reception interval by the timer means, the reception of the intermittent reception interval is completed immediately after the start of the next transmission period or immediately after the start. The wireless signal can be received by the means, and as a result, the time until the wireless signal can be normally received while reducing the power consumption of the wireless device, that is, the delay time of information transmission can be shortened.

  According to the invention of claim 2, since the end code is composed of the same bit string as the frame synchronization pattern, it is possible to detect the end code by the procedure for obtaining the frame synchronization by the frame synchronization pattern, and the processing in the reception control means It can be simplified.

  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 that causes the wireless transmission / reception unit 2 to transmit a radio signal including a notification message for notifying other radio units TR of the occurrence of the event, and when the event occurs The event generator 4 that notifies the controller 1 of the occurrence of the event, the notification unit 5 that notifies the controller 1 of the occurrence of the event from the event generator 4, and a battery such as a dry battery 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. The details are well known in the art and will be omitted.

  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. 2 shows a data format of a radio signal transmitted / received by the radio TR, and includes a synchronization bit (preamble: PA), a frame synchronization pattern (unique word: UW), a destination address DA, a source address SA, a message M, and a CRC. One frame Fk (k = 1, 2,..., M) is configured by the code. If the identification code of each wireless device TR is set as the destination address DA, only the wireless device TR having the identification code receives a radio signal and acquires a message. However, any wireless device TR is used as the destination address DA. By setting a special bit string (for example, a bit string in which all bits are set to 1) that are not assigned to the radio signal, it is possible to broadcast the radio signal and cause all the radio devices TR to acquire messages. 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.

  Here, the control unit 1 continuously transmits the radio signal of one frame from the radio transmission / reception unit 2 by the number (= m) that can be transmitted within one transmission period, but within one transmission period. A predetermined bit string X is added only to the end of the frame Fm to be transmitted last (see FIG. 2). This bit string X is composed of a synchronization bit PA 'for bit synchronization and an end code FE indicating the end of the transmission period.

  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 if the radio wave is not detected by the radio wave check, the wireless transmission / reception unit 2 is stopped and the counting of the intermittent reception interval is restarted.

  When synchronization is established, the control unit 1 sequentially fetches the destination address DA, the source address SA, and the message M received and demodulated by the wireless transmission / reception unit 2, and further performs a transmission error check using a CRC code. If there is no transmission error and the signal can be received normally, the control unit 1 notifies the occurrence of an event (fire occurrence, etc.) by processing a process according to the content of the received message M, for example, an alarm sound from the notification unit 5, and transmission error. If radio signal reception fails due to a radio wave, the radio wave check is performed 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 wireless transmission / reception unit 2 is activated in the frame Fm transmitted last, the frame synchronization pattern UW cannot be detected, but the control unit 1 detects the end code FE added to the end of the frame Fm. Set the intermittent reception interval to the same time as the pause period.

  Thus, in this embodiment, the end code FE is added only at the end of the frame Fm transmitted last in each transmission period, and when the reception of the radio signal fails as described above, the control unit 1 If the end code FE is detected, it is considered that the transmission period has been switched to the pause period, the intermittent reception interval is set to the same time as the pause period, and the counting of the intermittent reception interval by the timer is started. As long as the TR is transmitting a radio signal, the timing at which the counting of the intermittent reception interval set at the same time as the pause period is sure to 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. Note that the synchronization bit PA ′ is inserted immediately before the end code FE because the control unit 1 makes the end code FE even when the intermittent reception timing overlaps with the last frame Fm and synchronization by the synchronization bit PA cannot be achieved. It is to be able to acquire.

(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.

  The present embodiment is characterized in that the bit string of the end code FE is the same bit string as the frame synchronization pattern UW.

  Hereinafter, the reception operation, which is a feature 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 perform radio wave check by the RSSI signal every time the intermittent reception interval elapses. If is not captured, the wireless transmission / reception unit 2 is stopped and the intermittent reception interval is restarted. On the other hand, if a radio wave is detected by the radio wave check, the reception operation by the wireless transmission / reception unit 2 is started. If bit synchronization and frame synchronization are achieved within a predetermined time (one frame time), the control unit 1 executes the radio wave check again. To do. If the radio wave is detected by the radio wave check, the control unit 1 sequentially takes in the destination address DA, the transmission source address SA, and the message M received and demodulated by the wireless transmission / reception unit 2, and further performs a transmission error check using a CRC code. If there is no transmission error and the signal can be received normally, the control unit 1 notifies the occurrence of an event (fire occurrence, etc.) by processing a process according to the content of the received message M, for example, an alarm sound from the notification unit 5, and transmission error. If radio signal reception fails due to a radio wave, the radio wave check is performed again.

  On the other hand, if the radio wave check after the frame synchronization is not detected, the control unit 1 detects the end code FE composed of the same bit string as the frame synchronization pattern UW, that is, switches from the transmission period to the pause period. 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 a result, the time until the wireless signal can be normally received, that is, the delay time of information transmission, is shortened as compared with the case where the intermittent reception interval is not changed to the same time as the pause period as in the first embodiment. Can do.

  Thus, in this embodiment, since the bit string of the end code FE is the same bit string as the frame synchronization pattern UW, it is possible to detect the end code FE in a procedure for obtaining frame synchronization by the frame synchronization pattern UW. Compared to 1, there is an advantage that the processing in the control unit 1 can be simplified.

It is a system configuration figure showing Embodiments 1-3 of the present invention. It is a data format of the radio signal in the same as above. 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.

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 (2)

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. A transmission control means for stopping the transmission means repeatedly and 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 transmission control means adds a predetermined end code indicating the end of the transmission period to the end of the last frame in the transmission period and causes the transmission means to transmit,
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 further detects an end code when reception of the radio signal fails. If so, change the intermittent reception interval to a time equal to the pause period and restart counting of the intermittent reception interval by the timer means. If no end code is detected, restart the counting without changing the intermittent reception interval. A wireless transmission system characterized by the above. 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 wireless transmission system according to claim 1, wherein the transmission control means adds the end code comprising the same bit string as the frame synchronization pattern to the end of the last frame in the transmission period and causes the transmission means to transmit.

Images