JP2019004279A - Wireless device - Google Patents

Abstract

To achieve both rapid transmission of an urgent signal and reduction in interference by automatically setting a carrier sense level according to an installation environment.SOLUTION: A crime prevention sensor 10 functioning as a wireless device is allowed to transmit a wireless signal without performing carrier sensing, and when a signal including identical information such as sensor detection information is transmitted a plurality of times, a transmission control unit 12 transmits the signal at least once without performing the carrier sensing and performs the carrier sensing at least once and then transmits the signal. A carrier sense level setting unit 25 measures the reception level by a reception operation for a predetermined time and sets the carrier sense level on the basis of the reception level.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a radio apparatus that is allowed to transmit a radio signal without performing carrier sense.

  2. Description of the Related Art Conventionally, a radio apparatus that transmits a radio signal has a frequency band in which a signal can be transmitted without performing carrier sense and a frequency band in which it is obliged to perform carrier sense, depending on the radio law.

  As the frequency band that does not need to perform the carrier sense of the former, for example, there is a 400 MHz band allocated to the radio equipment of the radio station of the low power security system, as a frequency band for which carrier sense is obligatory, for example, for a low power telemeter, There are 400 MHz band and 920 MHz band allocated to the radio equipment for telecontrol and data transmission.

  In carrier sense, if different wireless devices with the same frequency transmit signals at the same time, interference will occur and communication will be hindered.Therefore, before starting transmission, a signal of the frequency used for transmission is received for a certain period of time. When it is confirmed that the used frequency is unused, transmission is started, thereby reducing interference between a plurality of devices and maintaining a wireless communication environment in which coexistence is possible.

  For example, it is assumed that three wireless devices exist in an area where they can communicate with each other and all perform carrier sense. Here, when one wireless device operates to perform carrier sense and starts transmission, when the remaining two devices operate to enter the transmission state and perform carrier sense, the wireless device that has been operated first performs transmission. Since it continues, it will be in a transmission standby state.

  Next, when the first operating wireless device finishes transmitting, the two wireless devices in the transmission standby state detect the unused of the used frequency by carrier sense, start transmitting, and simultaneously emit radio waves, Interference will occur. In order to avoid this, a plurality of wireless devices in a transmission standby state can be obtained by randomly varying the delay time from the detection of unused frequency in carrier sense to the start of transmission for each wireless device. At the same time, the transmission operation is prevented so that interference is avoided.

  On the other hand, specific low-power security radios handle highly urgent information, so when an event such as a fire or crime prevention occurs, transmission starts regardless of whether or not the transmission frequency is used by another device. Information can be transmitted quickly without causing time delays.

JP2012-105103A

  However, in a specific low-power security wireless device that is allowed to transmit a wireless signal without performing the conventional carrier sense, the function of the wireless device is provided in the same house by a home security system or the like. Although various types of sensors are arranged, the situation of the monitoring area varies, and when different sensors operate continuously, transmission of signals from the first operating sensor continues while other sensors Operates to transmit signals and interference occurs, and even though the signal transmitted from the sensor cannot be received normally by the receiver and no abnormal situation has occurred, an abnormality is judged and external monitoring is performed. There is a problem of being reported to the center.

  For example, it is assumed that a human sensor is installed in a hallway toward the entrance of a house, and a door sensor that detects opening and closing is installed in the entrance door. In this case, the resident moves toward the entrance through the corridor for going out, opens the entrance door, goes out, closes the entrance door, locks, and goes out. For this reason, a human sensor detects a resident heading to the entrance and starts a signal transmission operation. Then, the door sensor detects the opening of the entrance door and transmits a signal. Further, the door sensor detects the closing of the entrance door. Detects and transmits a signal, and basically no interference occurs in the signal transmission of the human sensor and the door sensor.

  However, human sensors are used not only in the corridors but also on the entrance side, and depending on the resident's movement, the human sensor detects the movement of the resident who opens and closes the front door and sends a signal. In some cases, the signal transmitted from the door sensor when the door sensor detects the closing of the front door and the signal transmitted from the human sensor are mixed and cannot be received by the receiver. In such a case, it is judged that the entrance door has been left open because it has not been confirmed after the entrance door has been opened. There is a problem that an abnormal occurrence is reported to the external monitoring center.

  In order to solve this problem, even a wireless device that is allowed to transmit a radio signal without performing carrier sense may reduce interference by transmitting a signal by performing carrier sense. Although it is conceivable, the original function of the specific low-power security radio that quickly transmits highly urgent information by transmitting a radio signal without performing carrier sense is impaired.

  In order to solve this problem, the applicant of the present invention, when transmitting a signal including the same information multiple times for a wireless device that is allowed to transmit a wireless signal without performing carrier sense, at least once A radio apparatus is considered that is provided with a transmission control unit that transmits a signal without performing sensing and transmits a signal by performing carrier sensing at least once.

  According to such a wireless device, a signal having a high urgency is transmitted without performing carrier sense once without transmitting a signal having the same contents multiple times without causing a time delay due to carrier sense. It can be transmitted quickly, and since the signal is transmitted by performing carrier sense once in the transmission of the signal multiple times, even if interference occurs due to the transmission of the signal of the same frequency used by another device By reducing interference and ensuring that the signal reaches the receiver or the like, both rapid transmission of information and reduction of interference can be achieved.

  By the way, when transmitting a signal by performing carrier sense in a wireless device that is allowed to transmit a radio signal without performing carrier sense, the presence / absence of carrier sense is determined from the reception level detected before the start of transmission. The carrier sense level is fixedly set in advance for identification, but the radio wave environment at the place where the wireless device is installed varies. If the carrier sense level is set higher, the possibility of interference increases. On the other hand, when the carrier sense level is set to be low, interference can be avoided, but there is a problem that transmission takes time.

  The present invention relates to a case where a signal having the same content is transmitted a plurality of times by a wireless device that is allowed to transmit a radio signal without performing carrier sense, and at least once when a signal is transmitted by performing carrier sense. An object of the present invention is to provide a radio apparatus that can achieve both rapid transmission of a highly urgent signal and reduction of interference by automatically setting a carrier sense level according to the installation environment.

(Wireless device)
The present invention provides a wireless device that is allowed to transmit a signal without performing carrier sense.
A carrier sense level setting unit that measures a reception level by a reception operation for a predetermined time and sets a carrier sense level based on the reception level;
When transmitting a signal including the same information a plurality of times, a transmission control unit that performs carrier sense based on the carrier sense level set by the carrier sense level setting unit at least once and transmits the signal;
Is provided.

(Continuous or stepwise setting of carrier sense level)
The carrier sense level setting unit changes the setting of the carrier sense threshold level continuously or stepwise between a predetermined minimum carrier sense level and a predetermined maximum carrier sense level.

(Minimum and maximum carrier sense levels)
The carrier sense level setting unit sets the minimum carrier sense level as a value based on reception sensitivity, and sets the maximum carrier sense level as a carrier sense level according to the standard of a wireless device that uses the same transmission frequency.

(Set carrier sense level based on communication priority)
The carrier sense level setting unit sets the carrier sense level to a low value when the priority of the signal to be transmitted is high, and sets the carrier sense level to a high value when the priority of the signal to be transmitted is low.

(Notification of installation environment)
The transmission control unit transmits a signal including the carrier sense level set by the carrier sense level setting unit and / or the measured reception level.

(No carrier sense for the first time, carrier sense for the second time and later)
The transmission control unit transmits a signal without performing carrier sense for the first time, and transmits a signal by performing carrier sense for the second and subsequent times.

(Carrier sense for the first time, no carrier sense for the second time and after)
The transmission control unit performs carrier sense for the first time and transmits a signal, and transmits the signal without performing carrier sense for the second and subsequent times.

(Basic effect)
The present invention measures a reception level by a reception operation for a predetermined time and sets a carrier sense level based on the reception level in a wireless device that is allowed to transmit a signal without performing carrier sense. When transmitting a signal including the same information as the carrier sense level setting unit a plurality of times, transmission for transmitting a signal by performing carrier sense based on the carrier sense level set by the carrier sense level setting unit at least once Since the control unit is provided, information on the case where the appropriate carrier sense level is automatically set according to the radio wave environment by performing the pre-monitoring of the radio wave environment at the installation location, and the signal is transmitted by performing carrier sense. It is possible to achieve both prompt transmission and reduction of interference.

(Effects of continuous or stepwise setting of carrier sense level)
The carrier sense level setting unit changes the carrier sense value level between a predetermined minimum carrier sense level and a predetermined maximum carrier sense level continuously or stepwise. In this case, the minimum carrier sense level is changed to the reception sensitivity. For example, if the measured reception level is between the maximum carrier sense levels of the minimum carrier sense level, the maximum carrier sense level is the standard carrier sense level of a wireless device that uses the same transmission frequency. For example, information when transmitting a signal by performing carrier sense by setting a carrier sense level between the reception level and the maximum value or by setting a carrier sense level obtained by adding a predetermined value to the reception level. It is possible to achieve both prompt transmission and reduction of interference.

(Set carrier sense level based on communication priority)
The carrier sense level setting unit sets the carrier sense level to a low value when the priority of the signal to be transmitted is high, and sets the carrier sense level to a high value when the priority of the signal to be transmitted is low. Signals that can be transmitted without time delay and that are less urgent are transmitted without interfering with other signals.

(Effects of notification of installation environment)
In addition, since the transmission control unit transmits a signal including the carrier sense level set by the carrier sense level setting unit and / or the measured reception level, the reception device side that receives the signal from the radio device Can know the radio wave environment of the place where the wireless device is installed, for example, if the carrier sense level or reception level is abnormally high, it can be seen that there is a noise source such as an electronic device near the wireless device, It is possible to take measures such as changing the installation location of the wireless device to improve the radio wave environment.

(The effect of no carrier sense for the first time and carrier sense for the second time and thereafter)
In addition, since the transmission control unit transmits the signal without performing carrier sense for the first time and transmits the signal by performing carrier sense for the second and subsequent times, priority is given to prompt transmission of a highly urgent signal. By transmitting a signal by performing carrier sense in a manner that recovers interference caused by transmission of a signal that does not perform carrier sense, both rapid transmission of information and reduction of interference can be achieved.

(Effect of having carrier sense for the first time and no carrier sense for the second and subsequent times)
In addition, since the transmission control unit performs carrier sense for the first time and transmits a signal and transmits the signal without performing carrier sense for the second and subsequent times, priority is given to reduction of interference, and carrier sense is performed. By transmitting the signal without performing carrier sense in the form of recovering the time delay due to signal transmission, it is possible to achieve both reduction of interference and rapid transmission of information.

Explanatory drawing which showed the crime prevention system where the radio | wireless apparatus of this invention is used Block diagram showing functional configuration of wireless device Explanatory drawing which showed the setting of the carrier sense level by the carrier sense level setting part of FIG. Time shunt showing a first embodiment of transmission control by the transmission control unit of FIG. The flowchart which showed the outline of the process by the signal processing part of FIG. The flowchart which showed 1st Embodiment of transmission control in step S3 of FIG. Time shunt showing a second embodiment of transmission control by the transmission control unit of FIG. The flowchart which showed 2nd Embodiment of transmission control in FIG.4 S3.

[Security system]
(Overview)
FIG. 1 is an explanatory diagram showing a wireless crime prevention system in which the wireless device of the invention is used. As shown in FIG. 1, the wireless crime prevention system includes an open / close sensor 10-1, a fire sensor 10-2, a human sensor 10-3, an abnormality notification light (outdoor indicator light) 26, a repeater 28, a receiving device ( (Security receiver, center device) 30 and portable setting device 32. Among these, each apparatus except the abnormality notification lamp 26 is disposed indoors in the house, and the abnormality notification lamp 26 is installed outside the house (for example, near the entrance).

  Hereinafter, the open / close sensor 10-1, the fire sensor 10-2, and the human sensor 10-3 may be collectively referred to as a “security sensor 10” as necessary. Further, in FIG. 1, one each of the open / close sensor 10-1, the fire sensor 10-2, the human sensor 10-3, the abnormality notification lamp 26, and the repeater 28 are provided. A stand may be provided.

(Security sensor)
The open / close sensor 10-1 detects the open / closed state of the door or window by magnetism or the like. When the open / close sensor 10-1 detects that the door or window is open, it transmits an open detection signal wirelessly. When it is detected that the opened door or window is closed, a close detection signal is transmitted wirelessly.

  The fire sensor 10-2 detects the occurrence of a fire by detecting smoke or heat. When a fire occurrence is detected, the fire sensor 10-2 transmits a fire detection signal wirelessly. The human sensor 10-3 detects a human body by detecting infrared rays. When a human body is detected, the human sensor 10-3 transmits a human body detection signal wirelessly.

  The abnormality notification lamp 26 is lit or blinked when a transfer signal is received from the receiving device 30 to notify the occurrence of an abnormality such as a fire to the outdoors.

  In addition, the open / close sensor 10-1, fire sensor 10-2, and human sensor 10-3 of the present embodiment receive information indicating the radio environment of the installation location such as the carrier sense level and the reception level by the environmental monitor, respectively. It is included in the detection signal and transmitted.

(Repeater)
The repeater 28 includes a relay function that receives a signal wirelessly transmitted from the security sensor 10 and transmits the received signal to the portable setting device 32 or the receiving device 30. The repeater 28 also has a relay function for receiving a signal wirelessly transmitted from the receiving device 30 and transmitting the signal to the portable setting device 32 or the abnormality notification lamp 26.

(Receiver)
The receiving device 30 receives the signal transmitted from the security sensor 10 via the repeater 28 or directly receives it, thereby monitoring and notifying the presence / absence of an abnormality. When the receiving device 30 detects an abnormality, it transmits a notification signal to the abnormality notification lamp 26 wirelessly to notify the abnormality, and if necessary, the abnormality occurrence is transferred to the security company by wire or wirelessly. It also functions as a wireless repeater to report. The receiving device 30 is installed, for example, in a place that is easy for the user to visually recognize, typically in an entrance, a living room, or the like.

  In addition, when receiving a signal transmitted from the security sensor 10, the receiving device 30 extracts the carrier sense level included in the received signal and the reception level by the environment monitor, and notifies the radio wave environment of the installation location of the security sensor 10. Take control.

(Portable setting device)
The portable setting device 32 is for remotely setting the security alert state of the receiving device 30 wirelessly. For example, the portable setting device 32 is carried by a user or used in an arbitrary place within a range where radio waves reach the repeater 28 or the receiving device 30 indoors.

  In particular, when the receiving device 30 is installed in a living room and the living room is away from the entrance, it takes time until the user releases the security mode in the living receiving device 30 after the user returns home. Since there is a possibility that the security mode cannot be canceled in time, the convenience of the user can be improved by arranging the portable setting device 32 in the vicinity of the entrance.

(Frequency band used)
In the security system of FIG. 1, two frequency bands are used as frequency bands for transmitting and receiving signals. Specifically, between the security sensor 10 and the repeater 28 or the receiving device 30, a 426 MHz band of a specific low-power security radio that does not require carrier sense is used. On the other hand, between the repeater 28, the receiving device 30, and the portable setting device 32, the 920 MHz band in which carrier sense is required is used, and high-speed processing is achieved by improving the communication speed, and communication reliability is improved. To improve.

[Wireless device]
(Overview)
FIG. 2 is a block diagram showing a functional configuration of the wireless device functioning as the security sensor of FIG. As shown in FIG. 2, the security sensor 10 including the open / close sensor 10-1, the fire sensor 10-2, and the human sensor 10-3 shown in FIG. 1 functions as a wireless device of the present invention, and the transmission control unit 24 And a signal processing unit 12 including a carrier sense level setting unit 25, a sensor unit 14, a wireless communication unit 16 including a transmission unit 18 and a reception unit 20, and an antenna 22. The security sensor 10 is operated by a battery power source (not shown).

(Wireless communication part)
The wireless communication unit 16 transmits and receives a packet signal composed of an ID part and a data part using a predetermined channel frequency in the 426 MHz band conforming to STD-30 known as a standard for specific low power security wireless. .

  In the specific low power security radio in the 426 MHz band, carrier sense is not obligatory, and when a signal is transmitted by the transmission unit 18, it is permitted to transmit a radio signal without performing carrier sense. For this reason, the wireless communication unit 16 that performs the specific low-power security radio in the 426 MHz band only needs to include the transmission unit 18, but in the wireless device of the present embodiment, the reception unit 20 is provided, The unit 20 enables carrier sensing to transmit a signal for a specific low power security radio in the 426 MHz band.

(Sensor part)
The sensor unit 14 is a general term for the functions of the open / close detection unit of the open / close sensor 10-1, the fire detection unit of the fire sensor 10-2, or the infrared detection unit of the human sensor 10-3 shown in FIG. When a fire or a human body is detected, the detection signal is output to the signal processing unit 12 as an event detection signal.

[Signal processing section]
The signal processing unit 12 includes a CPU, a memory, and a computer circuit having various input / output ports, and is provided with functions of a transmission control unit 24 and a carrier sense level setting unit 25 that are realized by executing a program.

(Transmission control unit)
When the transmission control unit 24 detects an input of an event detection signal from the sensor unit 14, the transmission control unit 24 enters a transmission control state, and includes a packet including an ID unit including identification information of the security sensor 10 and a data unit including a sensor type and a detection value. Control is performed to generate a signal and transmit a packet signal having the same content a plurality of times.

  Further, the transmission control unit 24 receives in the data part of the packet signal the reception level measured for environmental monitoring, which will be clarified later, and the carrier sense automatically set based on the measured reception level. Control to generate and transmit packet signal including level.

  In addition, when the packet signal having the same content is transmitted a plurality of times, the transmission control unit 24 transmits the signal at least once without performing carrier sense, and transmits the signal at least once after performing carrier sense. Take control.

  In the first embodiment of transmission control by the transmission control unit 24, when a packet signal having the same content is transmitted a plurality of times, the packet signal is transmitted without performing carrier sense for the first time, and carrier sense is performed for the second time and thereafter. To control transmission of the packet signal.

  In the second embodiment of transmission control by the transmission control unit 24, when a packet signal having the same content is transmitted a plurality of times, the packet signal is transmitted by performing carrier sense for the first time, and the carrier signal is transmitted for the second time and thereafter. Control is performed to transmit a packet signal without performing sensing.

(Carrier sense level setting part)
The carrier sense level setting unit 25 measures the reception level by the reception operation for a predetermined time and monitors the reception environment before the start of the operation of the security monitoring system and during the operation, and performs transmission control based on the reception level. Control for automatically setting the carrier sense level used for transmission to perform carrier sense by the unit 24 is performed.

  FIG. 3 is an explanatory diagram showing the setting of the carrier sense level by the carry sense level setting unit 25 of FIG. 2, and shows two setting methods as FIGS. 3 (A) and 3 (B).

  3A and 3B, a maximum value (Vth) max and a minimum value (Vth) min that determine the setting range of the carrier sense level Vth are set. Here, the minimum value (Vth) min is a value corresponding to the reception sensitivity of the receiving unit 20, and for example, a value of about 0.2 to 0.3 μV is set as the induced voltage of the antenna 22.

  Further, the maximum value (Vth) max is induced in an antenna having an absolute gain of 2.14 dB in the case of a specific low-power radio equipment (STD-T67) for which carrier sense is required to determine whether a frequency channel is free. When the voltage is in the 400 MHz band, the response time is specified to be within 20 msec at 7 μV. Therefore, for example, (Vth) max = 7 μV is set as the induced voltage of the antenna 22.

  Here, since the carrier sense level setting unit 25 receives the reception signal obtained by amplifying the induced voltage of the antenna 22 by the receiving unit 20, the minimum value (Vth) min in the carrier sense level setting unit 25 is the antenna induced level. For example, it is handled as a voltage of 2 to 3 mV obtained by receiving and amplifying a voltage of 0.2 to 0.3 μV. This is the same for the maximum value (Vth) max, which is treated as a voltage of 70 mV, for example, obtained by receiving and amplifying the antenna induced voltage of 7 μV.

The method of FIG. 3A is based on the reception level Vr measured over a predetermined time by the reception operation of the reception unit 20, and the difference {(Vth) max−Vr} from the reception level Vr with respect to the maximum value (Vth) max. Set by the following formula so that it becomes half.
Vth = Vr + {(Vth) max-Vr} / 2
In the method of FIG. 3A, the carrier sense level Vth is automatically set at the center between the reception level Vr indicating the radio wave environment (noise environment) at the installation location and the maximum value (Vth) max.

In the method of FIG. 3B, a predetermined fixed value ΔV is added to the reception level Vr to obtain Vth = Vt + ΔV.
Set as. In the method of FIG. 3B, by determining the size of the fixed value ΔV, it is possible to select whether the carrier sense level is set higher or lower.

  3A and 3B, the carrier sense level Vth is set following the reception level (noise level) indicating the radio wave environment at the installation location. That is, if the reception level Vr is small, the carrier sense level Vth is set low, and if the reception level Vr is high, the carrier sense level is also set high.

  Note that the method for setting the carrier sense level based on the reception level Vr indicating the radio wave environment at the installation location is not limited to FIGS. 3A and 3B, and includes an appropriate method as necessary.

[First embodiment of communication control]
(Communication control time chart)
As a first embodiment of communication control, the communication control unit 24 in FIG. 2 transmits a packet signal without performing carrier sense for the first time, and performs carrier sense for the second and subsequent times when the transmission state is set based on event detection. To transmit the packet signal having the same contents, for example, three times.

  4 is a time chart showing a first embodiment of transmission control by the communication control unit of FIG. 2, FIG. 4 (A) shows an event detection signal from the sensor unit, and FIG. 4 (B) has no interference. FIG. 4C shows the transmission operation and carrier sense when interference occurs.

  As shown in FIG. 4A, when an event detection signal is output from the sensor unit 14 by door opening / closing detection, fire detection or human body detection at time t1, the transmission control unit 24 enters the transmission operation state, and FIG. As shown in (1), the first packet signal is transmitted from time t1 by instructing the transmission unit 18 without performing carrier sense.

  Subsequently, at a time t3 when a predetermined time T1 has elapsed from the end of transmission at time t2, the second transmission operation state is entered, and in the second transmission operation state, carrier sense is performed and a packet signal is transmitted. That is, the receiving unit 20 is set in the receiving operation state at time t3, and the received signal level (received radio wave intensity) output from the receiving unit 20 is compared with the carrier sense level Vth set based on the instruction of the carrier sense level setting unit 24. In this case, if the signal is not transmitted from another security sensor and there is no interference, the received signal level is equal to or lower than the carrier sense level Vth, and the operation of the receiving unit 20 is stopped at time t4. By switching to the operation of the transmission unit 18, the second packet signal is transmitted from time t5 when the predetermined switching time T2 has elapsed.

  When the second transmission is completed at time t6, similarly, carrier sense is performed at time t7 when the predetermined time T1 has elapsed, and when the reception signal level is equal to or lower than the carrier sense level Vth, the time when the switching time T2 has elapsed. A third packet signal is transmitted from t9, and a series of transmission control is terminated.

  On the other hand, when an event detection signal is output at time t1, if other security sensors are in an interference state by transmitting signals at the same use frequency, as shown in FIG. The unit 24 performs the first transmission for transmitting the packet signal with the transmission unit 18 in the operating state at time t <b> 1 without performing carrier sense by the operation of the reception unit 20. At this time, if there is signal transmission by another security sensor, interference occurs, and the possibility that the signal cannot be normally received by the repeater or the receiver increases.

  When the first transmission without carrier sense ends at time t2, the receiving unit 20 is set in a receiving operation state at time t3 when the predetermined time T1 has elapsed, and the received signal level output from the receiving unit 20 exceeds the carrier sense level Vth. Or, if it is in the interference state indicated by the hatched portion as described above, the time after the predetermined time T1 has elapsed after the operation of the receiving unit 20 is stopped and the transmission unit 18 is not operated at the time t4. At time t5, the communication unit 20 is set in the reception operation state again. In this case, the reception signal level exceeds or exceeds the carrier sense level Vth. Therefore, the operation of the reception unit 20 is stopped at time t6 and the transmission unit 18 is in the transmission standby state. Continue.

  Subsequently, at time t7 when the predetermined time T1 has elapsed, the receiving unit 20 is again set in the receiving operation state. In this case, interference is eliminated and the received signal level is less than or less than the carrier sense level Vth. By stopping the operation of the receiving unit 20 at t8 and switching to the operation of the transmitting unit 18, the second packet signal is transmitted from the time t9 when the predetermined switching time T2 has elapsed.

  When the second transmission ends at time t10, similarly, carrier sense is performed at time t12 when the predetermined time T1 has elapsed, and when the received signal level is equal to or lower than the carrier sense level Vth, the time when the switching time T2 has elapsed. A third packet signal is transmitted from t13, and a series of transmission control is terminated.

  As described above, in the first embodiment of transmission control, when a signal having the same content is transmitted a plurality of times, the signal is transmitted without performing carrier sense for the first time, and the signal is transmitted with carrier sense for the second and subsequent times. In this way, priority is given to prompt transmission of signals with high urgency, and signal transmission is performed with carrier sense in the form of recovering interference caused by signal transmission without carrier sense. It is possible to reduce interference.

[Processing function of signal processor]
(Outline flowchart)
FIG. 5 is a flowchart showing an outline of processing by the signal processing unit of FIG. As shown in FIG. 5, when the signal processing unit 12 starts operation by turning on the battery power of the security sensor 10, the signal processing unit 12 operates the receiving unit 20 for a predetermined time by the operation of the carrier sense level setting unit 25 in step S1. Measure the reception level indicating the radio environment of the installation location.

  Subsequently, the process proceeds to step S2, and the carrier sense level setting unit 25 sets the carrier sense level Vth by the method shown in FIG. 3 (A) or FIG. 3 (B) based on the measured reception level.

  Subsequently, the process proceeds to step S <b> 3, and transmission control by the transmission control unit 24 is performed every time an event detection signal is input from the sensor unit 14. During this transmission control, the arrival of the environmental monitoring timing at every predetermined cycle is monitored in step S4. If it is determined that the environmental monitoring timing has been reached, for example, once a day, the processing returns to steps S1 and S2. The reception unit 20 is operated for a predetermined time by the operation of the carrier sense level setting unit 25 to measure the reception level indicating the radio environment at the installation location, and the carrier sense level Vth is reset based on the measured reception level. As a result, even if the radio wave environment at the place where the security sensor 10 is installed changes during operation, an appropriate carrier sense level is automatically set to follow the change in the radio wave environment.

  In the process of adopting the reception level indicating the radio wave environment of the installation location as the noise level Vr, if the measured value is different from the current noise level setting value Vr by a predetermined amount, the measured reception level is being transmitted by another signal. Therefore, the noise level Vr may not be adopted. In this case, for example, when a value that is shifted by a predetermined amount compared to the current set value is measured as a result of performing measurement several times at different times, the measured value is used as the noise level Vr. You may enable it to measure a noise level in the state where the other apparatus is not transmitting the signal suitably. The reception level may be measured by an appropriate method such as a single measurement value or a plurality of average values.

(Flow chart of communication control)
FIG. 6 is a flowchart showing a first embodiment of transmission control by the transmission control unit of FIG. As shown in FIG. 6, the transmission control unit 24 monitors the event occurrence by the detection operation of the sensor unit 14 in step S11, specifically, the input of the event detection signal. If the event occurrence is determined, the process proceeds to step S12. The transmission unit 18 is set in an operating state, and a packet signal including the carrier sense level and the reception level obtained by the environmental monitor measurement in addition to the event content is generated and transmitted without performing carrier sense.

  Subsequently, the transmission control unit 24 increments the transmission counter N indicating the number of transmissions by one in step S13, monitors the elapse of the predetermined time T1 in step S14, and proceeds to step S15 when determining the elapse of the predetermined time T1. Carrier sense for detecting the received signal level is performed with the unit 20 in the operating state.

  Subsequently, the transmission control unit 24 proceeds to step 16 to determine whether or not the received signal level detected by the carrier sense in step S15 is equal to or lower than the carrier sense level Vth. The process goes to step S14 and returns to step S14. When it is determined that the predetermined time T1 has elapsed, the process goes to step S15 to perform the next carrier sense.

  On the other hand, if the transmission control unit 24 determines in step S16 that the received signal level is equal to or lower than the carrier sense level Vth, the transmission control unit 24 proceeds to step S18, stops the reception operation of the reception unit 20, and sets the transmission unit 18 to the operating state. After a predetermined switching time T2, the second transmission for transmitting the packet signal including the carrier sense level and the reception level obtained by the environmental monitor measurement is performed.

  Subsequently, the transmission control unit 24 proceeds to step S9, increments the transmission counter N by one, and repeats the processing from step S4 until the maximum number of transmissions Nmax is determined in step S10.

[Second Embodiment of Communication Control]
(Communication control time chart)
As a second embodiment of communication control, the transmission control unit 24 in FIG. 2 performs a carrier sense for the first time and transmits a packet signal when the transmission state is set based on event detection, and performs a carrier sense for the second and subsequent times. By transmitting the packet signal without performing it, control is performed to transmit the packet signal having the same content, for example, three times.

  FIG. 7 is a time chart showing a second embodiment of transmission control by the transmission control unit of FIG. 2, FIG. 7A shows an event detection signal from the sensor unit, and FIG. 7B has no interference. FIG. 7C shows the transmission operation and carrier sense when interference occurs.

  As shown in FIG. 7A, when an event detection signal is output from the sensor unit 14 by door opening / closing detection, fire detection, or human body detection at time t1, the transmission control unit 24 enters the transmission operation state, and FIG. In the first transmission operation state, carrier sense is performed, and a packet signal including the carrier sense level and the reception level obtained by the environmental monitor measurement is transmitted.

  That is, the transmission control unit 24 sets the reception unit 20 to the reception operation state at time t1, and sets the reception signal level (reception radio wave intensity) output from the reception unit 20 based on the instruction of the carrier sense level setting unit 24. Compared to the carrier sense level Vth, in this case, if the signal is not transmitted from another security sensor and there is no interference, the received signal level is equal to or lower than the carrier sense level Vth, and the receiving unit at time t2 By stopping the operation of 20 and switching to the operation of the transmission unit 18, the first packet signal is transmitted from time t3 when a predetermined switching time T2 has elapsed.

  When the first transmission is completed at time t4, the second packet signal is transmitted by instructing the transmission unit 18 without performing carrier sense at time t5 after the elapse of the predetermined time T1. When the second transmission ends at time t6, similarly, at time t7 when the predetermined time T1 has elapsed, similarly, without performing carrier sense, the transmission unit 18 is instructed to transmit a third packet signal, and a series of transmissions are performed. End transmission control.

  On the other hand, when the event detection signal is output at time t1, when other security sensors are in an interference state by transmitting signals at the same use frequency, as shown in FIG. The transmission control unit 24 sets the reception unit 20 to the reception operation state at time t1, and compares the reception signal level output from the reception unit 20 with the carrier sense level Vth.

  In this case, assuming that the received signal level output from the receiving unit 20 is in an interference state indicated by the hatched portion where the carrier sense level exceeds or exceeds the carrier sense level Vth, the transmission control unit 24 stops the operation of the receiving unit 20 at time t2. At the same time, the transmission unit 18 is set in a transmission standby state without performing the operation of the transmission unit 18, and the reception unit 20 is set in the reception operation state again at time t3 after the predetermined time T1 has passed. In this case, too, the received signal level exceeds the carrier sense level Vth or Because of the above, at time t4, the operation of the receiving unit 20 is stopped and the transmitting unit 18 is set in a transmission standby state.

  Subsequently, the transmission control unit 24 sets the reception unit 20 to the reception operation state again at the time t5 when the predetermined time T1 has elapsed. In this case, the interference is eliminated, and the reception signal level is less than or less than the carrier sense level Vth. Therefore, by stopping the operation of the reception unit 20 at time t6 and switching to the operation of the transmission unit 18, the first packet signal is transmitted from time t7 when a predetermined switching time T2 has elapsed.

  When the first transmission ends at time t8, similarly, the second packet signal transmission is performed without performing carrier sense at time t9 when the predetermined time T1 has elapsed. When the second transmission is completed at time t10, at the time t11 when the predetermined time T1 has passed, similarly, without performing carrier sense, the transmission unit 18 is instructed to transmit a third packet signal, and a series of transmissions are performed. End transmission control.

  As described above, in the second embodiment of transmission control, when a signal having the same content is transmitted a plurality of times, a packet signal is transmitted by performing carrier sense for the first time, and a signal is transmitted without performing carrier sense for the second and subsequent times. By transmitting, priority is given to the reduction of interference, and then the signal is transmitted without carrier sense in the form of recovering the time delay due to the transmission of the signal with carrier sense. Quick transmission is possible at the same time.

(Communication control flowchart)
FIG. 8 is a flowchart showing a second embodiment of transmission control by the transmission control unit of FIG. As shown in FIG. 8, the transmission control unit 24 monitors the event occurrence by the detection operation of the sensor unit 14 in step S21, specifically, the input of the event detection signal. If the event occurrence is determined, the process proceeds to step S22. Carrier sensing for detecting the received signal level is performed with the receiving unit 20 in an operating state.

  Subsequently, the transmission control unit 24 proceeds to step 23 to determine whether or not the received signal level detected by the carrier sense in step S22 is equal to or lower than the carrier sense level Vth. The process goes to the transmission standby state, and when the elapse of the predetermined time T1 is determined in step S25, the process returns to step S22 to perform the next carrier sense.

  If the transmission control unit 24 determines in step S23 that the received signal level is equal to or lower than the carrier sense level Vth, the transmission control unit 24 proceeds to step S26, sets the transmission unit 18 in the operating state, and generates the carrier sense level based on the occurrence of the event. And the packet signal containing the reception level obtained by the environmental monitor measurement is transmitted.

  Subsequently, the transmission control unit 24 proceeds to step S27, increments the transmission counter N by 1, and then monitors the elapse of the predetermined time T1 in step S18. When the elapse of the predetermined time T1 is determined, the process proceeds to step S19. A packet signal is transmitted immediately without performing carrier sense in a transmission standby state.

  Subsequently, the transmission control unit 24 proceeds to step S30, increments the transmission counter N by one, and repeats the processing from step S28 until the maximum transmission seawater Nmax is determined in step S31.

[Modification of the present invention]
(Career sense)
The above embodiment is an example of a case where a signal is transmitted by performing carrier sense in a wireless device that is allowed to transmit a signal without performing carrier sense. However, the present invention is not limited to this. May be applied to the setting of the carrier sense level of a wireless device that is obligated.

(Transmission signal)
In the above embodiment, the signal having the same content is described as being transmitted a plurality of times. However, for example, a plurality of signals including the same information that are transmitted as a signal including the number of transmissions in addition to the content to be transmitted are included. It can also be applied to the case of sending twice.

(Send waiting time)
In the above embodiment, the waiting time from the signal transmission to the carrier sense and the waiting time from the carrier sense to the next carrier sense are set to be the same, but they may be different. Further, the respective standby times may be varied depending on the urgency of the signal to be transmitted. For example, the standby time may be shortened in an emergency such as a sensor reaction, and the standby time may be increased in a normal period such as regular communication. By doing so, it is possible to detect the absence of another carrier early and transmit a signal in an emergency while suppressing battery consumption during normal times.

(Transmission control)
In the above embodiment, when a signal having the same content is transmitted a plurality of times, in the first embodiment of the transmission control, the signal is transmitted without performing carrier sense for the first time, and the signal is performed by performing carrier sense for the second and subsequent times. However, signal transmission without carrier sense and signal transmission with carrier sense may be alternately repeated.

  In the second embodiment of transmission control, a signal is transmitted by performing carrier sense for the first time, and a signal is transmitted without performing carrier sense for the second time or later. Signal transmission without performing sensing may be alternately repeated.

  Further, signal transmission with carrier sense and signal transmission without carrier sense may be alternately repeated a plurality of times.

(Communications system)
Although the above embodiment has been described with respect to a crime prevention system, the present invention can also be applied to a communication system of any purpose and type other than this, for example, a wireless residential fire as a terminal device in a disaster prevention system Communication from a warning device or other battery-powered small wireless device to a receiver as a receiving device, or communication from a portable setting device as a terminal device to an engine starter as a receiving device in an automobile control system Even in this case, the present invention can be applied.

(Other)
The present invention is not limited to the above-described embodiment, includes appropriate modifications without impairing the object and advantages thereof, and is not limited by the numerical values shown in the above-described embodiment.

10: Security sensor 10-1: Open / close sensor 10-2: Fire sensor 10-3: Human sensor 12: Signal processing unit 14: Sensor unit 16: Wireless communication unit 18: Transmission unit 20: Reception unit 22: Antenna 24: Transmission control unit 25: carrier sense level setting unit 26: abnormality notification lamp 28: repeater 30: receiving device 32: portable setting device

Claims (7)

In a wireless device that is allowed to transmit a signal without performing carrier sense,
A carrier sense level setting unit that measures a reception level by a reception operation for a predetermined time and sets a carrier sense level based on the reception level;
A transmission control unit that transmits a signal by performing carrier sense based on the carrier sense level set by the carrier sense level setting unit at least once when transmitting a signal including the same information multiple times;
A wireless device comprising:
The wireless device according to claim 1, wherein
The carrier sense level setting unit changes the setting of the carrier sense threshold level between a predetermined minimum carrier sense level and a predetermined maximum carrier sense level continuously or stepwise.
The wireless device according to claim 2, wherein
The carrier sense level setting unit sets the minimum carrier sense level as a value based on a noise level or reception sensitivity, and sets the maximum carrier sense level as a carrier sense level based on a standard of a wireless device using the same transmission frequency. A wireless device characterized by the above.
The wireless device according to claim 2, wherein
The carrier sense level setting unit sets the carrier sense level to a low value when the priority of the signal to be transmitted is high, and sets the carrier sense level to a high value when the priority of the signal to be transmitted is low. apparatus.
2. The radio apparatus according to claim 1, wherein the transmission control unit transmits a signal including the carrier sense level set by the carrier sense level setting unit and / or the measured reception level. A wireless device characterized.
The wireless device according to claim 1, wherein
The transmission apparatus transmits a signal without performing carrier sense for the first time, and transmits a signal with carrier sense for the second time and thereafter.
The wireless device according to claim 1, wherein
The transmission apparatus is characterized by transmitting a signal by performing carrier sense for the first time and transmitting a signal without performing carrier sense for the second time and thereafter.

Images