JP5507979B2 - Wireless communication system - Google Patents

Description

  The present invention relates to a radio communication system including a plurality of radio stations, and more particularly to a radio communication system in which each radio station operates using a battery as a power source.

  For radio stations used in Japan, the characteristics of radio waves used (RF characteristics) such as occupied frequency bandwidth and adjacent channel leakage power must satisfy the provisions of the Radio Law. In the Radio Law, different standards (communication standards) are defined for each purpose of use. For example, “low-power radio stations” defined as one of the radio stations that do not require a license in the proviso to Article 4 of the Radio Law include “wireless stations for cordless telephones”, “specified low-power radio stations”, “low-power radio stations” There are “security system”, “low-power data communication system radio station”, etc., and the standards for the radio equipment of each radio station are stipulated by the equipment regulations of the law.

  Conventionally, there is one described in Patent Document 1 as a wireless communication system including a plurality of wireless stations that operate using a battery as a power source. In the conventional system described in Patent Document 1, each radio station intermittently activates a reception circuit to check whether or not a desired radio wave (a radio signal transmitted by another radio station) can be received. If radio waves are not captured, the average power consumption is greatly reduced by immediately stopping the receiving circuit and shifting to a standby state.

  As another conventional example, in the wireless communication system (fire alarm system) described in Patent Document 2, a specific fire alarm is used to confirm whether or not the fire alarm that is a radio station is operating normally. (Master station) sends regular monitoring messages periodically to other fire alarms (slave stations), and the slave station that has sent back a response message to the regular monitoring message returns a normal response message. Child stations that do not come in are judged abnormal.

JP 2008-176515 A JP 2009-251903 A

  However, when the intermittent reception operation is performed as described above, the timing of receiving the radio signal that should be received is delayed by the intermittent reception interval of the reception circuit. For example, in the conventional system described in Patent Document 1, 2a + b> T and a + 1.5b under the condition that the intermittent reception interval T is T> a, where a is the transmission period and b is the pause period. By setting the values a and b to be T to the transmission period and the pause period, respectively, the wireless signal is transmitted in the next (third) transmission period a when it cannot be received in the first (first) transmission period a. It can be received.

  Here, the wireless communication system that periodically transmits a wireless signal (a wireless signal including a periodic monitoring message) as in the conventional example described in Patent Document 2 is all within three times as in the conventional example described in Patent Document 1. When the wireless signal is received by the wireless station of the wireless station, the wireless station that transmits the wireless signal (the master station in the conventional example described in Patent Document 2) must transmit the wireless signal three times each time. Electricity will increase significantly.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a wireless communication system capable of reducing the power consumption of all the wireless stations on the transmission side and the reception side.

In order to achieve the above object, the invention of claim 1 is a radio communication system comprising a plurality of radio stations, and transmitting and receiving radio signals using radio waves as a medium between the plurality of radio stations. A wireless transmission / reception unit for transmitting / receiving a wireless signal, a timer unit for repeatedly counting a certain intermittent reception interval, and a wireless transmission / reception unit that is activated when a predetermined event occurs, and a message corresponding to the event during a predetermined transmission period In addition, the wireless signal transmitting / receiving means is stopped repeatedly when the event does not occur, and the intermittent reception interval is counted by the timer means. Control means for starting the wireless transmission / reception means each time the power supply is completed, and power supply means for supplying the operation power of each means using a battery as a power source The control unit of a specific radio station periodically transmits a radio signal including a regular monitoring message to all other radio stations from the radio transmission / reception unit, and the control unit of the other radio station If the wireless signal including the periodic monitoring message is received when the reception interval count is completed and the wireless transmission / reception unit is activated, a wireless signal including a response message is transmitted from the wireless transmission / reception unit to a specific wireless station. In the radio communication system, the other radio station counts the timer means within a predetermined periodical reception period including a transmission time at which a radio signal including a periodic monitoring message is transmitted from a specific radio station and before and after the transmission time. The second intermittent reception interval to be made is shorter than the first intermittent reception interval counted by the timer means outside the regular reception period. Shin intervals long and the second listen interval than the transmission period of the radio signal including periodic monitoring messages are characterized by shorter than the transmission period of the radio signal including periodic monitoring messages.

  According to the first aspect of the present invention, the intermittent reception intervals in all the other radio stations are relative within the regular reception period including before and after the time when the radio signal including the regular monitoring message is transmitted from the specific radio station. The radio signal can be reliably received by shortening the time period, and the power consumption can be reduced by relatively increasing the intermittent reception interval in all other radio stations outside the regular reception period. Can do. As a result, it is possible to reduce the power consumption of all the radio stations on the transmission side (specific radio station) and the reception side (other radio stations excluding the specific radio station).

  The invention of claim 2 is characterized in that, in the invention of claim 1, the time at which a radio signal including a periodic monitoring message is transmitted from the specific radio station is a fixed value.

  According to a third aspect of the present invention, in the first aspect of the invention, the control means of the specific radio station notifies all other radio stations of the time at which the radio signal including the periodic monitoring message is transmitted by radio signals. It is characterized by that.

  The invention of claim 4 is characterized in that, in the invention of claim 3, the control means of the specific radio station determines the time based on a unique identification code assigned to itself.

  The invention of claim 5 is characterized in that, in the invention of claim 4, the control means of the specific radio station randomly changes the time within the range of the regular reception period.

  According to the invention of claim 5, for example, even when a radio wave is transmitted at a constant period from a device existing within the receivable range of another radio station, the time at which the specific radio station transmits a radio signal is determined. Since it is changed randomly within the range of the regular reception period, it is possible to avoid a situation in which a radio wave transmitted from the device and a radio signal transmitted from a specific radio station always collide.

  The invention of claim 6 is the invention according to any one of claims 3 to 5, wherein the control means of the specific radio station notifies the next transmission time of the radio signal including the periodic monitoring message by the radio signal. It is characterized by.

  According to the present invention, there is an effect that power consumption of all radio stations on the transmission side and the reception side can be reduced.

It is a block diagram of a fire alarm device (master station and slave station) in an embodiment of the present invention. It is a frame format of the radio signal in the same as above. It is a time chart for demonstrating the operation | movement regarding regular monitoring same as the above. It is a flowchart for demonstrating operation | movement of the sub_station | mobile_unit regarding the regular monitoring same as the above.

  The technical idea of the present invention will be described below in a radio communication system (fire alarm system) in which a fire alarm device that emits a radio signal including a fire detection message using a radio wave as a medium while detecting a fire is used as a radio station. An embodiment to which is applied will be described.

  FIG. 1 is a system configuration diagram of this embodiment, and a fire alarm system is configured by a plurality of (only two in the drawing) fire alarm devices TR. In the following description, when the fire alarm devices TR are individually shown, they are expressed as fire alarm devices TR1, TR2,..., TRn, and when collectively shown, they are expressed as fire alarm devices TR.

  The fire alarm TR transmits a radio signal using radio waves as a medium from the antenna 3 and receives a radio signal transmitted from another fire alarm TR by the antenna 3, and a sound (buzzer sound or voice message). The main component is an alarm unit 5 for informing (sound from a speaker) a fire alarm (hereinafter referred to as “alarm sound”) and a memory unit 1a including a microcomputer and a rewritable nonvolatile semiconductor memory. When a fire is detected by the fire detection unit 4, a radio signal including a fire alarm message is transmitted from the radio transmission / reception unit 2 to cause the alarm unit 5 to sound an alarm sound and to notify other fire alarms TR of the fire alarm. The control unit 1 to be transmitted, the operation input receiving unit 6 that receives an operation input for stopping the alarm sound, as will be described later, and a battery such as a dry battery as a power source. And comprising a battery power supply unit 7 supplies power. The operation input receiving unit 6 has one or more switches (for example, push button switches). When the switch is operated, an operation input corresponding to each switch is received and an operation signal corresponding to the operation input is controlled. Output to part 1. Each of the fire alarm devices TR1, TR2,... Is assigned a unique identification code and stored in the memory unit 1a. The destination of the radio signal and the fire alarm devices TR1, TR2,. Can be identified.

  The radio transmission / reception unit 2 transmits / receives a radio signal using radio waves as a medium in accordance with “radio station of low power security system” defined in Article 6, Paragraph 4, Item 3 of the Radio Law Enforcement Regulations. In addition, the fire detection unit 4 detects fire by detecting smoke, heat, flames, and the like generated with the fire, for example. However, detailed configurations of the wireless transmission / reception unit 2 and the fire detection unit 4 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 a memory (ROM or EEPROM) (not shown) by a microcomputer. When the fire detection unit 4 detects the occurrence of a fire, the control unit 1 drives a buzzer included in the alarm unit 5 to sound an alarm sound, or an alarm stored in the memory (or the memory unit 1a) in advance. In order to notify a fire alarm by sounding a voice message (for example, “This is a fire”) on the speaker, and to notify the fire alarm also in other fire alarm devices TR, a radio signal including a fire alarm message is transmitted. The wireless transmission / reception unit 2 transmits the data. Also, when the wireless transmission / reception unit 2 receives a wireless signal transmitted from another fire alarm device TR, the control unit 1 controls the alarm unit 5 to sound an alarm sound. That is, in the control unit 1, when the fire detection unit 4 detects a fire, the alarm unit 5 sounds an alarm sound to notify the fire alarm, and the wireless transmission / reception unit 2 transmits a radio signal including the fire alarm message. Have.

  Here, in the radio equipment regulation Article 49-17 “Radio equipment of radio stations of the low power security system” of the Radio Law Enforcement Regulation, the period during which radio signals may be continuously transmitted (transmission period) is 3 seconds or less. It is stipulated that the period (pause period) provided between the transmission period and the transmission period in which the radio signal should not be transmitted is 2 seconds or more (see No. 5 of the same article). For this reason, in the control unit 1 in the present embodiment, the wireless signal is transmitted during the transmission period that complies with the wireless facility rules, and the transmission is stopped and received during the suspension period.

  In order to extend the battery life of the battery power supply unit 7 as much as possible, the control unit 1 uses a timer (timer means) built in the microcomputer to set a predetermined intermittent reception interval (however, the intermittent reception interval is longer than the transmission period). Each time the intermittent reception interval is counted, the wireless transmitter / receiver 2 is activated to check whether a desired radio wave (wireless signal transmitted by another fire alarm device TR) can be received, If radio waves are not captured, the average power consumption is greatly reduced by immediately stopping the wireless transmission / reception unit 2 and 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 fire alarm device TR1 (hereinafter referred to as a master station) activates the wireless transmission / reception unit 2 periodically (for example, every 24 hours) to establish other fire alarm devices TR2, TR3,. A radio signal including a periodic monitoring message is transmitted in order to confirm (periodic monitoring) whether or not (hereinafter referred to as a slave station) is operating normally. In the slave stations TR2,..., The control unit 1 monitors whether or not the fire detection unit 4 has failed and whether or not the battery power supply unit 7 has run out of battery at regular intervals (for example, every hour), and the monitoring result ( The presence or absence of a failure and the presence or absence of a battery are stored in the memory unit 1a, and when a periodic monitoring message is received from the master station TR1, a notification message for notifying the monitoring result stored in the memory unit 1a ( A response signal) is returned to the master station TR1. After transmitting the radio signal including the notification message, the control unit 1 of the master station TR1 switches the radio transmission / reception unit 2 to the reception state, receives the radio signal transmitted from each of the slave stations TR2,. There is a slave station TR2,... That does not transmit a radio signal including a notification message within a predetermined time after transmission of the included radio signal, or a notification message transmitted from any of the slave stations TR2,. When notifying the result of monitoring that the battery has run out, the slave station TR2,. ) Has also been reported. When the control unit 1 of the master station TR1 and the slave stations TR2,... Determines that a failure or a battery has run out, a warning sound for immediately informing the occurrence of an abnormality (failure or battery runout) from the alarm unit 5. (Buzzer sound, voice message, etc.) are sounded from the speaker of the alarm unit 5.

  Further, the control unit 1 of the master station TR1 detects the fire and causes the alarm unit 5 to sound an alarm sound and transmits a fire alarm message to each of the slave stations TR2,..., Or any of the slave stations TR2. After receiving the fire alarm message from,..., The wireless transmission unit 2 is caused to transmit a synchronous beacon at a constant cycle. This synchronous beacon is a signal that defines a time slot required for performing TDMA (time division multiple access) wireless communication (hereinafter referred to as “synchronous communication”) between a plurality of fire alarms TR. The one cycle is divided into a plurality of time slots, and one different time slot is allocated to each of the slave stations TR2,. Then, a message from the master station TR1 to the slave station TR2,... Is transmitted in a synchronous beacon, and a radio signal including a message from the slave station TR2,... To the master station TR1 is assigned to each slave station TR2,. Stored in the current time slot and transmitted. Therefore, it is possible to reliably avoid collision of radio signals transmitted from a plurality of fire alarm devices TR (the master station TR1 and the slave stations TR2,...). Although the time slot assignment to each fire alarm device TR may be fixed, the time slot assignment information may be notified to each slave station TR2,... By a synchronous beacon transmitted from the master station TR1.

  FIG. 2 shows a frame format of a radio signal transmitted and received by the fire alarm device TR. A synchronization bit (preamble: PA), a frame synchronization pattern (unique word: UW), a destination address DA, a source address SA, a message M, One frame is composed of a CRC code. Here, if the identification code of each fire alarm device TR is set as the destination address DA, only the fire alarm device TR of the identification code receives a radio signal and acquires a message. By setting a special bit string that is not assigned to the fire alarm TR (for example, a bit string with all bits set to 1), a wireless signal is broadcast (multicast) to obtain a message for all the fire alarm TRs. Can be made. For example, a radio signal including a fire alarm message is broadcast from the master station TR1 to all the slave stations TR2,.

  For example, when the fire detection unit 4 detects a fire in the slave station TR2, the control unit 1 of the slave station TR2 sounds an alarm sound from the alarm unit 5 and activates the wireless transmission / reception unit 2 to transmit a radio signal including a fire alarm message. It transmits to all other fire alarm devices TR (master station TR1 and other slave stations TR3,...). At this time, the control unit 1 of the transmission source slave station TR2 continuously transmits the radio signal by the number of frames that can be transmitted within the transmission period, and the radio transmission / reception unit 2 during the pause period (reception period) after the transmission period. To the receiving state.

  Here, if the low-power radio is used, the wireless communication distance can be sufficiently covered as long as it is within an area of a normal house. Therefore, the fire source child station TR2 can connect other fire alarm devices TR (master station TR1 and master station TR1). It is usually possible to send a message to other slave stations TR3,. However, as described above, the master station TR1 periodically monitors the slave stations TR2 to TR4, and the normality of the communication path is confirmed between the master station TR1 and each of the slave stations TR2 to TR4. However, since the communication path between the slave stations TR2 to TR4 is not confirmed, there is a possibility that a message does not reach a certain slave station due to the influence of an obstacle, for example.

  Therefore, the control unit 1 of the master station TR1 that has received the fire alarm message transmits a radio signal including the fire alarm message to the other slave stations TR3 and TR4 other than the slave station TR2 that is the transmission source. When the control unit 1 of the other slave stations TR3 and TR4 receives the fire alarm message transmitted from the slave station TR2 or the master station TR1, it immediately sounds an alarm sound from the alarm unit 5 and sends a fire alarm message from the radio transceiver unit 2. A response message (ACK) for confirming reception is returned by a radio signal. In addition, when all of the fire alarms TR notify the fire alarm (sounds an alarm sound) when a fire is detected by at least one fire alarm TR in this manner, hereinafter, it is referred to as “fire interlocking”. .

  When receiving the ACK from all the other slave stations TR3 and TR4, the control unit 1 of the master station TR1 causes the radio transmission / reception unit 2 to transmit a synchronization beacon for defining a time slot at a constant period. In the present embodiment, the first time slot TS1 is assigned to the child station TR2, the second time slot TS2 is assigned to the child station TR3, and the third time slot TS3 is assigned to the child station TR4.

  By the way, as described above, radio signals (radio signals including fire alarm messages and regular monitoring messages) transmitted from other fire alarm devices TR are received without delay in a situation where each fire alarm device TR is performing intermittent reception. For this purpose, the intermittent reception interval Tx must be set to a time shorter than the transmission period Ts of the radio signal. However, as described above, the cycle in which the radio signal including the periodic monitoring message is transmitted is very long, such as several tens of hours (for example, 24 hours). In addition, the radio signal including the fire alarm message is several to ten years. Alternatively, since most cases are not transmitted until battery replacement, setting the intermittent reception interval Tx to a time shorter than the transmission period Ts of these radio signals greatly increases wasteful power consumption.

  Therefore, in the present embodiment, as shown in the time chart of FIG. 3, the transmission time of the radio signal (radio signal including the periodic monitoring message) periodically transmitted from the master station TR1 and the predetermined time period including the time before and after the transmission time. Only during the regular reception period Tw, the intermittent reception interval Tx of the slave stations TR2,... Is shorter than the radio signal transmission period Ts (second intermittent reception interval Tx2). The intermittent reception interval Tx of TR2,... Is set to a time sufficiently longer than the transmission period Ts (first intermittent reception interval Tx1).

  Here, processing (operation) performed by the control unit 1 of each slave station TRi (i = 2, 3,...) Will be described with reference to the flowchart of FIG.

  First, the control unit 1 starts counting the time until the regular reception period Tw starts with a built-in timer (step S1), and the first intermittent reception interval is set to the intermittent reception interval Tx until the count ends. Tx1 is set and counted (steps S2 and S3). Every time counting of the first intermittent reception interval Tx1 ends, the wireless transmission / reception unit 2 is activated to perform intermittent reception (steps S4 and S5). Then, when the counting of the time until the regular reception period Tw starts is completed, the control unit 1 starts counting the time until the regular reception period Tw ends (step S6), and until the count ends. The interval is counted by setting the second intermittent reception interval Tx2 to the intermittent reception interval Tx (steps S7 and S8), and every time the second intermittent reception interval Tx2 is counted, the wireless transmission / reception unit 2 is activated and intermittently counted. Reception is performed (steps S4 and S5).

  Thus, according to the present embodiment, the other radio stations (child stations TR2,...) Transmit the radio signal including the periodic monitoring message from the specific radio station (master station TR1) and the transmission time. The second intermittent reception interval Tx2 counted by the timer within a predetermined periodic reception period Tw including before and after the period is shorter than the first intermittent reception interval Tx1 counted by the timer outside the periodic reception period Tw. Since the first intermittent reception interval Tx1 is longer than the transmission period Ts of the wireless signal including the periodic monitoring message and the second intermittent reception interval Tx2 is shorter than the transmission period Ts of the wireless signal including the periodic monitoring message, In the regular reception period Tw including before and after the time at which the radio signal including the regular monitoring message is transmitted from the station TR1, the interval between all the other slave stations TR2,. Since the reception interval (second intermittent reception interval Tx2) becomes relatively short, the radio signal can be reliably received, and all the other slave stations TR2,. As the intermittent reception interval (first intermittent reception interval Tx1) at the time becomes relatively long, power consumption can be reduced. As a result, the transmission side (master station TR1) and the reception side (slave stations TR2,...) The power consumption of all radio stations (fire alarm device TR) can be reduced.

  Here, in order to reliably receive a radio signal including a fire alarm message transmitted from any of the fire alarm devices TR without delay, the transmission period of the radio signal is longer than the first intermittent reception interval Tx1. Just do it. Note that if the transmission period is lengthened, the power consumption of the source fire alarm device TR will increase, but there are very few opportunities to transmit a radio signal including a fire alarm message. Even if the transmission period of the included wireless signal is made longer than the first intermittent reception interval Tx1, it is considered that there is substantially no influence on the power consumption.

  By the way, the time at which the radio signal including the regular monitoring message is transmitted from the master station TR1 is set as a fixed value (for example, a fixed time every day or a fixed period starting from the operation start point of the system). You may memorize | store in the memory part 1a. Alternatively, when the identification codes of all the slave stations TR2,... Are registered in the master station TR1 before the system starts operating, a radio signal including the time information is transmitted from the master station TR1 to each slave station TR2,. You may make it notify. At this time, the time notified from the master station TR1 may be determined by the control unit 1 of the master station TR1 based on a unique identification code assigned to itself, and further within the range of the regular reception period Tw. The time may be changed at random. For example, even when radio waves are transmitted at regular intervals from devices within the receivable range of the slave stations TR2,..., The time at which the master station TR1 transmits a radio signal is random within the range of the regular reception period Tw. Therefore, it is possible to avoid a situation in which a radio wave transmitted from the device and a radio signal transmitted from the master station TR1 always collide with each other.

  Further, when the control unit 1 of the master station TR1 transmits a periodic monitoring message, the transmission time of the next periodic monitoring message is included in the wireless signal together with the periodic monitoring message and transmitted to notify each slave station TR2,. It doesn't matter if you do.

  By the way, the intermittent reception interval Tx between the master station TR1 and the plurality of slave stations TRn may be synchronized according to the reception timing of the regular monitoring message transmitted from the master station TR1. That is, each slave station TRn may reset the count of the intermittent reception interval Tx at the timing when the regular monitoring message is received. Even in such a case, the reception timing of the regular monitoring message transmitted from the master station TR1 may be shifted due to the error of the timer that the master station TR1 and the plurality of slave stations TRn count the intermittent reception interval Tx. As described above, it is desirable to relatively shorten the intermittent reception interval Tx only during the period including the time when the regular monitoring message is transmitted from the master station TR1.

TR1, TR2 Fire alarm (radio station)
1 Control unit (control means, timer means)
2 Wireless transceiver (wireless transceiver)
7 Battery power supply (power supply means)

Claims (6)

A wireless communication system comprising a plurality of wireless stations and transmitting and receiving wireless signals using radio waves as a medium between the plurality of wireless stations,
Each radio station starts a radio transmission / reception unit for transmitting / receiving a radio signal, a timer unit for repeatedly counting a certain intermittent reception interval, and a radio transmission / reception unit when a predetermined event occurs, and the event is transmitted during a predetermined transmission period. The radio signal containing the message corresponding to the message is transmitted, and the operation of pausing the transmission of the radio signal during a predetermined pause period is alternately repeated. When the event does not occur, the radio transmission / reception means is stopped, and the timer means intermittently A control means for starting the wireless transmission / reception means every time counting of the reception interval is completed, and a power supply means for supplying an operation power source of each means using a battery as a power source,
The control unit of a specific radio station periodically transmits a radio signal including a regular monitoring message to all other radio stations from the radio transmission / reception unit,
If the control means of the other radio station receives the radio signal including the periodic monitoring message when the counting of the intermittent reception interval is completed and the radio transmission / reception means is activated, the control means for the specific radio station In a wireless communication system for transmitting a wireless signal including a response message from a wireless transmission / reception unit,
The other radio station receives a second intermittent reception that is counted by a timer unit within a predetermined periodical reception period including a transmission time at which a radio signal including a periodic monitoring message is transmitted from a specific radio station and before and after the transmission time. The interval is made shorter than the first intermittent reception interval counted by the timer means outside the regular reception period, and the first intermittent reception interval is longer than the transmission period of the radio signal including the regular monitoring message and the second wireless communication systems of intermittent reception interval being shorter than the transmission period of the radio signal including periodic monitoring messages.   The radio communication system according to claim 1, wherein a time at which a radio signal including a periodic monitoring message is transmitted from the specific radio station is a fixed value.   2. The radio communication system according to claim 1, wherein the control means of the specific radio station notifies all other radio stations of the time at which a radio signal including a periodic monitoring message is transmitted by radio signals.   4. The radio communication system according to claim 3, wherein the control means of the specific radio station determines the time based on a unique identification code assigned to itself.   5. The radio communication system according to claim 4, wherein the control means of the specific radio station changes the time at random within the range of the regular reception period.   The wireless communication system according to any one of claims 3 to 5, wherein the control means of the specific wireless station notifies the next transmission time of the wireless signal including the periodic monitoring message by the wireless signal.

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