JP4919073B2 - Wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system suitable for a security system for reporting information such as a gas leak sensor and a fire sensor.

  In recent years, a low-power security system has been developed as a system for automatically reporting output signals of various sensors installed in a general home or office to a security center for uses such as fire alarm and crime prevention.

  In general, a low-power security system is connected to a security center, a wireless master unit connected to the security center via a telephone line, and a wireless master unit via a specific low-power wireless line, and various sensors (fire sensors). , Gas leak sensors, etc.) are connected to a plurality of wireless slave units.

  In this low-power security system, one communication channel is set in advance for each of the wireless master device and the plurality of wireless slave devices connected thereto, and the wireless slave device is used using the communication channel. Is transmitted to the wireless master unit. Here, a so-called carrier sense method for determining whether or not the channel being used is already in use at the start of data transmission is not employed.

  In this low-power security system, for example, when a fire occurs, the fire sensor sends a detection signal to the wireless slave unit, and the wireless slave unit generates communication data for notifying the fire via a specific low-power wireless line. , Transmit to the wireless master unit at the maximum transmission level within the legal regulation range. At this time, the wireless slave unit continuously transmits the same communication data for each frame while the fire sensor continues to transmit the detection signal. However, in order to enable transmission of communication data by other wireless slave units, transmission is performed for a certain time (for example, 3 seconds) with a certain interval (for example, 2 seconds). That is, the operation of stopping transmission for 2 seconds after repeating transmission for 3 seconds is repeated. The wireless master unit receives the communication data from the wireless slave unit and transfers it to the security center via the telephone line. As a result, the security center detects the occurrence of an emergency such as a fire based on the contents of the transferred communication data (see Patent Document 1).

  However, in this low power security system, there is a problem that the alarm operation lacks responsiveness due to the transmission suspension period. Thus, it is conceivable to improve the responsiveness of the alarm operation by continuously transmitting communication data without providing a transmission suspension period.

  However, when communication data is transmitted continuously without providing a transmission suspension period, there are the following problems. In the low-power security system, the use channel of the wireless master device and the plurality of wireless slave devices is set to one specific channel, and the carrier sense method is not adopted, so that the wireless power device is located at approximately the same distance from the wireless master device. Multiple wireless slave units may transmit communication data at the same time. In this case, since the electric field strengths of these transmitted radio waves are the same in the wireless master unit, these transmitted radio waves interfere with each other. The machine cannot receive any wireless slave unit's communication data.

JP 2003-224482 A (paragraph 0002)

  The present invention has been made in view of such problems, and an object of the present invention is to provide a plurality of wireless transmitters that continuously transmit data for a predetermined time using the same communication channel, and the wireless transmission thereof. In a wireless communication system having a wireless receiver that receives data transmitted from a wireless device, even if multiple wireless transmitters located at approximately the same distance from the wireless receiver transmit data simultaneously, the wireless receiver This is to prevent a situation where the data of the wireless transmitter cannot be received.

The first aspect of the present invention is a wireless communication system including a plurality of wireless transmitters each continuously transmitting data for a predetermined time using the same communication channel, and a wireless receiver that receives data transmitted from the wireless transmitter. In the communication system, one wireless transmitter has first transmission level control means for controlling the transmission output level of the data to be a predetermined level for the predetermined time, and the other wireless transmitter has the data And a second transmission level control means for controlling the transmission output level to temporarily become lower than the predetermined level within the predetermined time.
According to a second aspect of the present invention, in the wireless communication system according to the first aspect, the second transmission level control means periodically changes the transmission output level within the predetermined time.
According to a third aspect of the present invention, in the wireless communication system according to the first aspect, the second transmission level control means controls the level to be lower than the predetermined level at the beginning of the predetermined time. And

[Action]
According to the first aspect of the present invention, when a plurality of wireless transmitters transmit data at the same time, the wireless receiver controls the other wireless transmitter so that the transmission output level is lower than a predetermined level. Receive data transmitted from one wireless transmitter at a time.
According to the invention of claim 2, when a plurality of wireless transmitters transmit data simultaneously, the wireless receiver periodically receives the data transmitted from one wireless transmitter within the predetermined time.
According to the invention of claim 3, when a plurality of wireless transmitters transmit data at the same time, the wireless receiver is transmitted from one wireless transmitter immediately after the one wireless transmitter starts transmitting data. Receive data.

  According to the present invention, a radio having a plurality of radio transmitters that transmit data continuously for a predetermined time using the same communication channel and a radio receiver that receives data transmitted from these radio transmitters. In a communication system, even when a plurality of wireless transmitters located at approximately the same distance from a wireless receiver transmit data at the same time, it is possible to prevent a situation in which the data of any wireless transmitter cannot be received by the wireless receiver. .

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a wireless communication system according to an embodiment of the present invention.
The wireless communication system includes a plurality of wireless transmitters 1 a, 1 b,... And a single wireless receiver 3.

  Sensors 2a, 2b,... For detecting emergency situations such as fire sensors and gas leak sensors are connected to the wireless transmitters 1a, 1b,. The wireless receiver 3 includes an alarm display unit 4. Further, the wireless transmitters 1a, 1b,... Are arranged at substantially equal distances from the wireless receiver 3.

  The radio transmitters 1a, 1b,... And the radio receiver 3 can receive the data transmitted by the radio transmitters 1a, 1b,. Here, the wireless transmitters 1a, 1b,... And the wireless receiver 3 conform to the standard of the low power security system, and one communication channel is set in advance, and the communication channel is used. Then, data transmission from the wireless transmitters 1a, 1b,... To the wireless receiver 3 is performed.

  FIG. 2 is a block diagram showing the configuration of the wireless transmitter 1a. The wireless transmitter 1b and the like are similarly configured. The wireless transmitter 1 a includes a control unit 11, an I / F (interface) unit 12, a transmission unit 13, an operation unit 14, and a display unit 15 each connected to the control unit 11. A sensor 2 a is connected to the I / F unit 12, and an antenna 16 is connected to the transmission unit 13.

  The control unit 11 includes a microcomputer having a CPU, a ROM, a RAM, and the like, and controls the entire wireless transmitter 1a. The control unit 11 includes a transmission output level control unit 11a that controls the level (intensity) of a low-power radio wave transmitted from the transmission unit 13 to the antenna 16, and a transmission output for storing information used to control the transmission output level. A level information storage unit 11b. In addition, although not shown, a channel information storage unit for storing the number of a communication channel used for data transmission is provided.

  The operation unit 14 includes various keys and switches, and is used when the user operates the wireless transmitter 1a. The display unit 15 is composed of a lamp or the like, and displays the operating state of the wireless transmitter 1a.

  FIG. 3 is a block diagram showing the configuration of the wireless receiver 3. The wireless receiver 3 includes a control unit 31, a reception unit 32, an operation unit 33, a display unit 34, and an alarm display unit 4 each connected to the control unit 31. An antenna 35 is connected to the receiving unit 32.

  The control unit 31 includes a microcomputer having a CPU, ROM, RAM, and the like, and performs overall control of the wireless receiver 3 and the like. Although not shown in the figure, a channel information storage unit for storing the number of a communication channel used for receiving data is provided.

  The receiving unit 32 separates communication data from the low-power radio wave received by the antenna 35 and sends it to the control unit 31. The operation unit 33 includes various keys and switches, and is used when the user operates the wireless receiver 3. The display unit 34 is composed of an LCD or the like, and displays the operating state of the wireless receiver 3 and the like. The alarm display unit 4 includes a lamp, a speaker, and the like, and notifies a fire alarm, a gas leak alarm, and the like. The display unit 34 may also be used as the alarm display unit 4.

  In the wireless communication system configured as described above, the sensors 2a, 2b,... Connected to any one of the wireless transmitters 1a, 1b,. When the detection signal is generated, the detection signal is sent to the control unit 11 through the I / F unit 12. The control unit 11 creates low-power wireless communication data based on the received detection signal and outputs the communication data to the transmission unit 13. At this time, the transmission level control unit 11a in the control unit 11 reads the transmission output level control information (details will be described later) stored in the transmission level information storage unit 11b, and based on this, outputs the transmission output to the transmission unit 13. Outputs a level control signal. The transmission unit 13 amplifies the communication data received from the control unit 11 to a transmission output level corresponding to the transmission output level control signal received from the control unit 11, and sends it to the antenna 16.

  In the wireless receiver 3, a low-power radio wave carrying communication data transmitted from one of the wireless transmitters 1a, 1b,... Is received by the antenna 35, and the communication data is separated by the receiving unit 32 and controlled. Sent to the unit 31. The control unit 31 analyzes the communication data, generates a signal for notifying the result by the alarm display unit 4, and outputs the signal to the alarm display unit 4. Based on the input signal, the alarm display unit 4 displays a lamp that indicates the contents of an emergency such as a fire or gas leak, and to which wireless transmitter the sensor that has detected it is connected. Output audio. Thereby, the person around the wireless receiver 3 can know the type of emergency and the place where the emergency occurs.

  Here, in the wireless communication system of this embodiment, among the sensors 2a, 2b,... Connected to the wireless transmitters 1a, 1b,. In order to prevent a wireless receiver from receiving communication data of any wireless transmitter due to interference of transmission radio waves as a result of simultaneous transmission of communication data by a plurality of wireless transmitters, a plurality of wireless transmitters 1a , 1b,... Are controlled as follows.

  FIG. 4 is an example when the total number of wireless transmitters of the wireless communication system of FIG. 1 is 2, and when the sensors 2a and 2b connected to the wireless transmitters 1a and 1b are simultaneously generating detection signals. The transmission power level and the temporal change of the reception enabled / disabled state of the wireless receiver 3 are shown.

  When the sensors 2a and 2b simultaneously generate detection signals, as shown in FIG. 4, the wireless transmitters 1a and 1b generate the same communication data for each frame, and the sensors 2a and 2b generate detection signals. Transmit repeatedly. Here, frame numbers F1 to F8 are shown.

  During this repeated transmission operation, the transmission output level of the transmitter 13 of the wireless transmitter 1a is set to the maximum level H within the legal regulation range. On the other hand, the transmission output level of the wireless transmitter 1b is set to the maximum level H in the first transmission frame F1, the transmission output level is reduced to L (for example, 60% of H) in the second to third transmission frames, and thereafter Levels H and L are set alternately every two transmission frames.

  As a result, in the wireless receiver 3, in the transmission frames (F1, F4, F5, etc.) in which the transmission output levels of both the wireless transmitters 1a and 1b are H, both transmission radio waves interfere with each other. In the transmission frame (F2, F3, F6, F7) in which the transmission output level of the wireless transmitter 1b is L, the transmission output level from the wireless transmitter 1a is higher. The transmission radio wave does not interfere, and communication data transmitted from the wireless transmitter 1a can be received (◯ in the figure). Therefore, if the detection target of the sensor 2a connected to the wireless transmitter 1a is set to the most urgent emergency (eg, fire), the emergency can be reliably detected.

  FIG. 5 shows a case where the transmission frame timing of the wireless transmitter 1b in FIG. 4 is delayed by approximately half of one frame period. In this case, the wireless receiver 3 can receive the communication frame data of the frame numbers F3 and F7.

  FIG. 6 shows an example in which the total number of wireless transmitters in the wireless communication system of FIG. 1 is 3, and sensors 2a, 2b, 2c connected to the wireless transmitters 1a, 1b, 1c (1c not shown). (2c is not shown) shows the transmission output level when the detection signal is generated at the same time, and the temporal change of the receivable / impossible state of the wireless receiver 3.

  When the sensors 2a, 2b, and 2c simultaneously generate detection signals, as shown in FIG. 6, the wireless transmitters 1a, 1b, and 1c generate the same communication data for each frame, and the sensors 2a, 2b, and 2c detect Send repeatedly during signal generation. Here, frame numbers F1 to F15 are shown.

  During this repeated transmission operation, the transmission output level of the transmitter 13 of the wireless transmitter 1a is set to a constant value of the maximum level H within the legal regulation range. On the other hand, the transmission output level of the wireless transmitter 1b is set to the maximum level H in the first transmission frame F1, the transmission output level is lowered to L in the second to fifth transmission frames, and thereafter one transmission frame is transmitted. After setting to H, the operation of setting four transmission frames to L is repeated. The transmission output level of the wireless transmitter 1c is set to the maximum level H in the first transmission frame F1, the transmission output level is lowered to L in the second to seventh transmission frames, and thereafter one transmission frame is transmitted. After setting to H, the operation of setting 6 transmission frames to L is repeated.

  As a result, in the wireless receiver 3, in the transmission frames (F1, F6, F8, F11, F15, etc.) in which the transmission output level of at least one of the wireless transmitters 1b or 1c is H, the wireless transmitters 1a and 1b or 1c The transmission radio waves interfere with each other and cannot receive any communication data (X in the figure), but the transmission frames (F2 to F5, F7, F9 to F10, F12 to F14) with the transmission output level of the wireless transmitters 1b and 1c are L. ), Since transmission radio waves do not interfere, communication data transmitted from the wireless transmitter 1a can be received (◯ in the figure).

  FIG. 7 shows a case where the transmission frame timings of the wireless transmitters 1b and 1c in FIG. 6 are delayed by approximately half and three and a half of one frame period, respectively. In this case, the wireless receiver 3 can receive the communication data of the frame numbers F5, F8 to F9, and F13 to F15.

  FIG. 8 shows a case where the total number of wireless transmitters in the wireless communication system of FIG. 1 is 3, and the sensors 2a, 2b, 2c connected to the wireless transmitters 1a, 1b, 1c simultaneously generate detection signals. 6 is another example of a temporal change in a transmission output level when the wireless receiver 3 is in a reception enabled / disabled state of the wireless receiver 3.

  In this figure, the temporal change in the transmission output level of the wireless transmitter 1a is the same as in FIG. On the other hand, for the wireless transmitters 1b and 1c, it can be said that the level H of the first frame in FIG. 6 is deleted and one frame is advanced. That is, the wireless transmitter 1b repeats the operation of setting 4 frames to level L and then setting the next frame to level H, and the wireless transmitter 1c sets 6 frames to level L and then setting the next frame to level H. Is repeated from the first transmission frame.

  As a result, in the wireless receiver 3, the transmissions transmitted from the wireless transmitter 1a in the transmission frames (F1 to F4, F6, F8 to F9, F11 to F13) whose transmission output levels of the wireless transmitters 1b and 1c are L are shown. Data can be received (○ in the figure). That is, since it can be received at a timing earlier than that of FIG. 6 by one frame period, an alarm can be issued earlier.

  Next, there are three wireless transmitters 1a, 1b, and 1c constituting the wireless communication system in FIG. 1, and the transmission output levels of the wireless transmitters 1b and 1c are changed in three stages of H, M, and L. The case will be described. Here, H is the maximum level within the legal regulation range, and M and L are, for example, 80% and 60% of H, respectively. 6 to 8 show the operation when the sensors 2a, 2b, and 2c connected to the wireless transmitters 1a, 1b, and 1c simultaneously generate detection signals. In the operation example, a case where there is a sensor that does not generate a detection signal among the sensors 2a, 2b, and 2c will be described.

  As shown in FIG. 9, there are seven combinations of patterns in which each of the three wireless transmitters 1a, 1b, and 1c transmits data according to the detection signals of the sensors 2a, 2b, and 2c. In this figure, ◯ indicates a state where data transmission is being performed, and x indicates a state where data transmission is not being performed.

  The pattern P1 in this figure is a pattern in which three wireless transmitters 1a, 1b, and 1c transmit data, P2 to P4 are patterns in which two of the three wireless transmitters transmit data, and P5 to P7 are In this pattern, only one wireless transmitter transmits data. Among these patterns, radio wave interference does not occur in the patterns P5 to P7, and therefore the data transmitted from the wireless transmitter is reliably received by the wireless receiver 3. Accordingly, the case of the patterns P1 to P4 will be described below.

  10 to 13 show the transmission output levels of the wireless transmitters 1a, 1b, and 1c when the wireless transmitter operates in the patterns P1 to P4 1a, 1b, and 1c, respectively, and whether or not the wireless receiver 3 can receive signals. It shows the time change of the state.

  When the levels of the wireless transmitters 1b and 1c are changed in three stages in this way, the pattern P4 shown in FIG. 13, that is, when the wireless transmitter 1a whose transmission output level is always H does not perform data transmission. Compared with the case where the level is changed in two steps, the number of frames in which the wireless receiver 3 can receive data increases.

  As described above, according to the communication system of the embodiment of the present invention, a plurality of wireless transmitters 1a, 1b, etc. arranged at equal distances from the wireless receiver 3 are used as detection signals of the sensors 2a, 2b, etc. Based on this, even when the communication data is continuously transmitted at the same time, the wireless receiver 3 can reliably receive the communication data transmitted from one of the wireless transmitters. Will improve.

  In the above description, the wireless receiver 3 displays an alarm. However, the wireless receiver 3 may be connected to a security center via a telephone line and notified to the security center.

It is a figure which shows the structure of the radio | wireless communications system of embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless transmitter of FIG. It is a block diagram which shows the structure of the radio | wireless receiver of FIG. It is a figure which shows the time change of those transmission output levels in case the number of radio | wireless transmitters is 2, and the receivable / impossible state of a radio | wireless receiver. FIG. 5 is a diagram illustrating a case where the transmission frame timing of one wireless transmitter in FIG. 4 is delayed. It is a figure which shows an example of the time change of those transmission output levels in case the number of radio | wireless transmitters is 3, and the receivable / impossible state of a radio | wireless receiver. It is a figure which shows the case where the timing of the transmission frame of the two radio | wireless transmitters of FIG. 6 is overdue. It is a figure which shows another example of the time change of those transmission output levels when the number of radio | wireless transmitters is 3, and the receivable / impossible state of a radio | wireless receiver. It is a figure which shows the pattern of the combination of the presence or absence of the data transmission by three radio | wireless transmitters. It is a figure which shows the time change of the transmission output level of three radio | wireless transmitters, and the receivable / impossible state of a radio | wireless receiver in case three radio | wireless transmitters operate | move by the pattern P1 of FIG. It is a figure which shows the time change of the transmission output level of three radio | wireless transmitters, and the receivable / impossible state of a radio | wireless receiver in case three radio | wireless transmitters operate | move by the pattern P2 of FIG. It is a figure which shows the time change of the transmission output level of three radio | wireless transmitters, and the receivable / impossible state of a radio | wireless receiver in case three radio | wireless transmitters operate | move by the pattern P3 of FIG. It is a figure which shows the time change of the transmission output level of three radio | wireless transmitters, and the receivable / impossible state of a radio | wireless receiver in case three radio | wireless transmitters operate | move by the pattern P4 of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a, 1b ... Wireless transmitter, 3 ... Wireless receiver, 4 ... Alarm display part, 11 ... Control part, 13 ... Transmission part.

Claims (3)

A wireless communication system having a plurality of wireless transmitters each continuously transmitting data for a predetermined time using the same communication channel, and a wireless receiver for receiving data transmitted from the wireless transmitter,
One wireless transmitter has first transmission level control means for controlling the transmission output level of the data to be a predetermined level for the predetermined time, and the other wireless transmitter sets the transmission output level of the data to the data transmission level. A wireless communication system comprising: a second transmission level control means for controlling to temporarily become lower than the predetermined level within a predetermined time. The wireless communication system according to claim 1, wherein
The wireless communication system, wherein the second transmission level control means changes the transmission output level periodically within the predetermined time. The wireless communication system according to claim 1, wherein
The wireless communication system, wherein the second transmission level control means performs control so as to become a level lower than the predetermined level at the beginning of the predetermined time.

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