JP7624635B2 - Alarm system, alarm device, communication method, and program - Google Patents

Description

This disclosure relates to alarm technology, and in particular to an alarm system, an alarm device, a communication method, and a program that use a multi-hop network.

Smart meters are installed in each home, and data is transmitted between the smart meters using a wireless multi-hop method, allowing the base station to collect data. In a wireless multi-hop method, there is a risk that a communication anomaly may occur between nodes, making it impossible to send a communication message from the collection node to the destination sensor node. In such a case, a node outside the relay route that detects the anomaly will autonomously build an alternative route and continue communication (see, for example, Patent Document 1).

JP 2017-50746 A

When a communication failure occurs in a multi-hop network, retransmission is performed. If the communication failure continues even after retransmission, it becomes necessary to switch the relay route. It is necessary to switch the relay route smoothly.

This disclosure has been made in light of these circumstances, and its purpose is to provide a technology that smoothly switches relay routes in a multi-hop network.

In order to solve the above problems, an alarm system according to one aspect of the present disclosure comprises multiple alarm devices that form a multi-hop network extending from a relay device. The multiple alarm devices include a first alarm device, a second alarm device, and a third alarm device. The first alarm device receives a signal from the relay device via the second alarm device, and if the first alarm device fails to receive a signal from the relay device via the second alarm device, it receives a signal from the relay device via the third alarm device, and if the first alarm device switches from a relay route including the second alarm device to a relay route including the third alarm device, it sends a route switching notification to the third alarm device to notify the relay device of the switch in the relay route.

Another aspect of the present disclosure is an alarm device. This alarm device is one of multiple alarm devices that make up a multi-hop network spreading from a relay device, and when this alarm device is referred to as a first alarm device, the multiple alarm devices also include a second alarm device and a third alarm device, and is equipped with a communication unit that receives a signal from the relay device via the second alarm device, and a control unit that controls the communication unit. If reception of a signal from the relay device via the second alarm device fails, the communication unit receives a signal from the relay device via the third alarm device, and if the communication unit switches from a relay route including the second alarm device to a relay route including the third alarm device, it transmits a route switch notification to the third alarm device to notify the relay device of the switch of the relay route.

Yet another aspect of the present disclosure is a communications method. This method is a communications method in an alarm device among multiple alarm devices that make up a multi-hop network spreading from a relay device, and when this alarm device is referred to as a first alarm device, the multiple alarm devices also include a second alarm device and a third alarm device, and comprises the steps of receiving a signal from the relay device via the second alarm device, receiving a signal from the relay device via the third alarm device if reception of a signal from the relay device via the second alarm device has failed, and, when the relay route including the second alarm device has been switched to a relay route including the third alarm device, sending a route switching notification to the third alarm device to notify the relay device of the relay route switch.

In addition, any combination of the above components, and conversions of the expressions of this disclosure between methods, devices, systems, recording media, computer programs, etc., are also valid aspects of this disclosure.

This disclosure makes it possible to smoothly switch relay routes in a multi-hop network.

1 is a diagram showing a configuration of an alarm system according to an embodiment of the present invention; FIG. 2 is a diagram showing the configuration of the fire alarm device of FIG. 1. 3(a)-(e) are diagrams showing the structure of a superframe used in the alarm system of FIG. FIG. 2 is a diagram showing a configuration of a relay device in FIG. 1; FIG. 2 is a diagram showing an overview of communications in the alarm system of FIG. 1; 6(a)-(b) are diagrams showing the formats of the periodic signal and the response signal used in the alarm system of FIG. 7(a)-(b) show another overview of communications in the alarm system of FIG. FIG. 2 shows an overview of routing in the alarm system of FIG. 1; FIG. 2 is a sequence diagram showing a routing procedure in the alarm system of FIG. 1 . 10(a)-(b) are diagrams showing a situation when a communication failure occurs in the alarm system of FIG. 11(a)-(b) are diagrams showing an overview of retransmission in the alarm system of FIG. 12(a)-(b) show another overview of retransmission in the alarm system of FIG. 13(a)-(b) are diagrams showing an overview of notifications in the alarm system of FIG. 14(a)-(b) are diagrams showing an overview of slot switching and aging in the alarm system of FIG. 15(a) and 15(b) are diagrams showing an overview of communications after route switching in the alarm system of FIG.

Before describing the present disclosure in detail, an overview will be provided. This embodiment relates to an alarm system installed in facilities such as apartment buildings, detached houses, offices, and hospitals. In the alarm system, a relay device is connected to a management device, and multiple fire alarms are connected to the relay device via a wireless multi-hop network. In such a network, the management device corresponds to the upper side, and the fire alarm with the greatest number of hops from the relay device corresponds to the lower side. When a fire alarm detects a fire, it transfers the detection result to the relay device, and the relay device transfers the detection result to the management device. When the management device receives the detection result, it selects one or more fire alarms that will sound, and transmits an instruction to sound to the selected one or more fire alarms as the final destination. The relay device and the fire alarm transfer the instruction to sound to the fire alarm at the final destination, and the fire alarm at the final destination sounds when it receives the instruction to sound.

Here, if the line for signals from the relay device to the fire alarm with the greatest number of hops from the relay device is called the "downstream line," the line for signals from the fire alarm with the greatest number of hops to the relay device is called the "upstream line." In this embodiment, a frame is formed by arranging multiple time slots, and a superframe is formed by arranging multiple frames. Furthermore, one fire alarm is assigned to one time slot for the downstream line (hereinafter referred to as the "downstream communication time slot") and one time slot for the upstream line (hereinafter referred to as the "upstream communication time slot"). The downstream communication time slot is used for transfer on the downstream line, and the upstream communication time slot is used for transfer on the upstream line.

In the downstream line, in addition to instructions to sound, the relay device periodically transmits a signal (hereafter referred to as a "periodic signal") to confirm that each fire alarm is alive. This periodic signal is also used by the relay devices and fire alarms in the multi-hop network to establish and maintain synchronization. In the upstream line, in addition to detection results, each fire alarm transmits a response signal to the periodic signal. In the following explanation, the periodic signal, response signal, detection results, and instructions to sound are sometimes collectively referred to as "communication signals".

Fire alarms in a multi-hop network must monitor whether detection results are being transmitted in the upstream communication time slots assigned to other lower-level fire alarms. In particular, as the number of lower-level fire alarms increases, the number of upstream communication time slots that must be monitored increases, resulting in increased power consumption by the fire alarms.

In order to suppress the increase in power consumption of fire alarms, monitoring time slots are introduced. As described above, a frame includes multiple downstream communication time slots and multiple upstream communication time slots. The frame also includes a monitoring time slot (hereinafter referred to as a "monitoring time slot") for a fire alarm that is scheduled to transmit a communication signal in the assigned upstream communication time slot to transmit a signal (hereinafter referred to as a "monitoring signal"). Each fire alarm waits to receive a monitoring signal in the monitoring time slot. If a fire alarm receives a monitoring signal in the monitoring time slot, it waits to receive a communication signal in the assigned upstream communication time slot. On the other hand, if a fire alarm does not receive a monitoring signal in the monitoring time slot, it does not wait to receive a communication signal in the assigned upstream communication time slot.

If the relay device does not receive a response signal from the fire alarm, it resends the periodic signal. However, depending on the communication environment, there is a possibility that the resent periodic signal may not always reach the fire alarm. Such communication environments may include, for example, the presence of a fixed obstruction (iron door) due to a layout change, or interference from stationary jamming waves. Under such circumstances, it is necessary to smoothly switch relay routes in a multi-hop network.

In the following, this embodiment will be described in the following order: (1) basic configuration, (2) routing, (3) occurrence of communication failure, (4) retransmission on a new route (part 1), (5) retransmission on a new route (part 2), (6) notification of route change, (7) slot switching/aging, and (8) communication after route switching.
(1) Basic Configuration Fig. 1 shows the configuration of an alarm system 1000. The alarm system 1000 includes a first fire alarm device 600a to a sixth fire alarm device 600f, collectively referred to as fire alarm devices 600, a relay device 700, and a management device 800. The number of fire alarm devices 600 is not limited to "6", and the number of relay devices 700 is not limited to "1".

The alarm system 1000 is applied to facilities such as homes, offices, and commercial facilities, and is a system that detects fires and notifies the occurrence of a fire. The multiple fire alarms 600 are, for example, residential fire alarms and are equipped with fire detection sensors. The multiple fire alarms 600 are installed, for example, on the ceiling of the facility, but may also be installed on the walls, etc.

Here, the first fire alarm device 600a to the sixth fire alarm device 600f form a multi-hop network extending from the relay device 700. For example, a relay route is formed that connects the relay device 700 and the first fire alarm device 600a, and a relay route is formed that connects the relay device 700, the second fire alarm device 600b, the third fire alarm device 600c, and the fourth fire alarm device 600d. In addition, a relay route is also formed that connects the relay device 700, the second fire alarm device 600b, the third fire alarm device 600c, the fifth fire alarm device 600e, and the sixth fire alarm device 600f. Such relay routes are determined by each fire alarm device 600 and are also shared by the relay device 700 and the management device 800.

In these relay routes, the first fire alarm device 600a and the second fire alarm device 600b can communicate with the relay device 700 with a hop number of "1", and the third fire alarm device 600c can communicate with the relay device 700 with a hop number of "2". The fourth fire alarm device 600d and the fifth fire alarm device 600e can communicate with the relay device 700 with a hop number of "3", and the sixth fire alarm device 600f can communicate with the relay device 700 with a hop number of "4". Focusing on the fifth fire alarm device 600e, the fifth fire alarm device 600e receives a signal from the relay device 700 via the third fire alarm device 600c, but can also receive a signal from the relay device 700 via the first fire alarm device 600a or the fourth fire alarm device 600d. When the fifth fire alarm device 600e connects to the first fire alarm device 600a or the fourth fire alarm device 600d, the number of hops to the relay device 700 changes.

In this way, the relay device 700 performs wireless or wired communication with the multiple fire alarm devices 600 that make up the multi-hop network. The relay device 700 can also be said to relay communication between the multiple fire alarm devices 600 included in the multi-hop network. Furthermore, the relay device 700 is connected to the management device 800 by a cable, and performs wired communication with the management device 800. The relay device 700 and the management device 800 may also perform wireless communication.

The management device 800 is, for example, a controller for a HEMS (Home Energy Management System) installed in the facility. The management device 800 can communicate with multiple devices installed in the facility. The multiple devices include, for example, air conditioners, lighting equipment, water heaters, etc. that have communication functions. The management device 800 can also communicate with a relay device 700 installed in the facility. Furthermore, the management device 800 can also communicate with each fire alarm 600 via the relay device 700.

2 shows the configuration of the fire alarm 600. The fire alarm 600 includes a communication unit 620, a processing unit 622, a control unit 624, a fire detection sensor 630, and a buzzer 632, and the control unit 624 includes a monitoring unit 626. The processing unit 622 and the control unit 624 may be integrated. A known technology may be used for the fire detection sensor 630. For example, the fire detection sensor 630 may be an optical smoke detection sensor, and may detect a fire by detecting smoke during a fire using diffuse reflection of light. For example, the fire detection sensor 630 may be a heat detection sensor, and may detect a fire by detecting heat during a fire. For example, the fire detection sensor 630 may be a carbon monoxide detection sensor, and may detect a fire by detecting the concentration of carbon monoxide generated by combustion during a fire. For example, the fire detection sensor 630 may be an infrared detection sensor, and may detect a fire by detecting infrared rays emitted by combustion during a fire.

The communication unit 620 performs wireless communication with other fire alarm devices 600 or relay devices 700. The communication unit 620 may perform wired communication. The processing unit 622 processes signals received by the communication unit 620 and generates signals to be transmitted from the communication unit 620. The control unit 624 controls the operation of the communication unit 620 and the processing unit 622. Details of the processing by the control unit 624 will be described later. The buzzer 632 is capable of sounding a buzzer sound. The fire alarm 600 may not include the buzzer 632, but may include a fire detection sensor 630, that is, a configuration having both a detection function and a communication function. Such a fire alarm 600 can also be said to be a detector that can alert the detection of a fire.

Figures 3(a)-(e) show the structure of a superframe 1010 used in the alarm system 1000. As shown in Figure 3(a), a certain period is defined as a superframe 1010. The superframe 1010 is arranged repeatedly. The superframe 1010 is divided into multiple frames 1020. As shown in Figure 3(b), one frame 1020 is divided into multiple time slots 1030. Of the multiple time slots 1030, one or more time slots 1030 at the beginning are used as "downstream communication time slots". The multiple downstream communication time slots are time slots 1030 to be assigned to each of the multiple fire alarm devices 600 in order to transmit a signal from the relay device 700, and are arranged on the time axis.

One or more time slots 1030 following the downstream communication time slot are used as "monitoring time slots". One or more time slots 1030 following the one or more monitoring time slots are used as "upstream communication time slots". The multiple upstream communication time slots are time slots 1030 to be assigned to each of the multiple fire alarm devices 600 to transmit signals to the relay device 700, and are arranged on the time axis. One or more time slots 1030 following the upstream communication time slot are used as "free time slots". The number of downstream communication time slots and the number of upstream communication time slots are the same, and are equal to or greater than the number of fire alarm devices 600 included in the multi-hop network. The number of monitoring time slots is equal to or greater than the maximum number of hops in the multi-hop network. There may be no free slots.

Figure 3(c) shows a timeslot 1030 to be used as a timeslot for downstream communication or an timeslot for upstream communication. The length of the timeslot 1030 is set to "A". Figure 3(d) shows a timeslot 1030 to be used as a monitoring timeslot. The length of the timeslot 1030 is set to "B". "B" is set to a value smaller than "A".

Figure 3 (e) shows an example of the use of multiple frames 1020 in a superframe 1010. In the first frame 1020 of the superframe 1010, "regular monitoring" is performed. "Regular monitoring" is a process in which the relay device 700 transmits a regular signal, and the fire alarm device 600 transmits a response signal in response to the regular signal, whereby the relay device 700 confirms the survival of the fire alarm device 600 that is the sender of the received response signal. "Same route retransmission" is performed in the "two" frames 1020 following "regular monitoring." In "same route retransmission," if there is a fire alarm device 600 whose survival was not confirmed in "regular monitoring," the same process is performed in the same relay route as "regular monitoring."

In the "two" frames 1020 following the "same route retransmission", "another route retransmission" is performed. In the "other route retransmission", if there is a fire alarm 600 whose survival was not confirmed in the "regular monitoring" and "same route retransmission", the same process is performed on a relay route different from that for the "regular monitoring" and "same route retransmission".

In the multiple frames 1020 following the "different route retransmission", "detection waiting" is performed. "Detection waiting" is a process of waiting for at least one fire alarm 600 to detect the occurrence of a fire and transmit a detection result. When the relay device 700 receives a detection result from at least one fire alarm 600, the relay device 700 transmits an instruction to sound. When the survival of all fire alarms 600 is confirmed in regular monitoring, same route retransmission, and different route retransmission, the remaining same route retransmission or different route retransmission frames 1020 are used for "detection waiting". Regular monitoring, same route retransmission, and different route retransmission are performed at predetermined timing, so the fire alarm 600 and the relay device 700 recognize the timing of regular monitoring, same route retransmission, and different route retransmission. Also, in the "regular monitoring", "same route retransmission", and "same route retransmission" frames 1020, when a fire alarm 600 detects the occurrence of a fire, the fire alarm 600 transmits a detection result.

Figure 4 shows the configuration of the relay device 700. The relay device 700 can be said to be a control device for the multiple fire alarm devices 600 that make up the multi-hop network. The relay device 700 includes a communication unit 710 and a control unit 720, where the communication unit 710 includes an output unit 712, and the control unit 720 includes an allocation unit 722. The communication unit 710 has a communication function for communicating with the multiple relay devices 700, and also has a communication function for communicating with the management device 800. The control unit 720 controls the operation of the relay device 700.

The communication unit 710 communicates with the multiple fire alarm devices 600 that make up the multi-hop network, and receives the results of the routing performed by each fire alarm device 600. The routing performed by each fire alarm device 600 will be described later, but each relay route as shown in Figure 1 is formed based on the routing results.

Based on the result of the routing, the allocation unit 722 allocates a combination of one downstream communication time slot and one upstream communication time slot shown in FIG. 3(b) to one fire alarm 600. The output unit 712 outputs the allocation result of the allocation unit 722 to the multiple fire alarms 600 as slot information. The slot information indicates the correspondence between the combination of the downstream communication time slot and the upstream communication time slot and the fire alarm 600.

Figure 5 shows an overview of communication in the alarm system 1000, particularly an overview of "regular monitoring." Here, it is assumed that the relay route in the alarm system 1000 is formed as shown in Figure 1. In Figure 5, the first fire alarm 600a to the sixth fire alarm 600f are shown as "C1" to "C6," respectively, and the relay device 700 is shown as "M."

The downstream communication time slots are assigned to the relay device 700, the first fire alarm 600a, the second fire alarm 600b, the third fire alarm 600c, the fourth fire alarm 600d, the fifth fire alarm 600e, and the sixth fire alarm 600f in order from the front. As described above, the number of hops from the first fire alarm 600a and the second fire alarm 600b to the relay device 700 is "1", and the number of hops from the third fire alarm 600c to the relay device 700 is "2". In addition, the number of hops from the fourth fire alarm 600d and the fifth fire alarm 600e to the relay device 700 is "3", and the number of hops from the sixth fire alarm 600f to the relay device 700 is "4". In other words, the fire alarms 600 with a smaller number of hops to the relay device 700 are assigned to the front of the downstream communication time slots.

The sixth fire alarm device 600f, the fifth fire alarm device 600e, the fourth fire alarm device 600d, the third fire alarm device 600c, the second fire alarm device 600b, the first fire alarm device 600a, and the relay device 700 are assigned to the upstream communication time slots in order from the front. In other words, the fire alarm device 600 with the greater number of hops to the relay device 700 is assigned to the front of the upstream communication time slots.

When focusing on the fifth fire alarm device 600e, in the downstream communication time slot, the fifth fire alarm device 600e is assigned to the rear of the fourth fire alarm device 600d and in front of the sixth fire alarm device 600f. In the upstream communication time slot, the fifth fire alarm device 600e is assigned to the rear of the sixth fire alarm device 600f and in front of the fourth fire alarm device 600d.

The monitoring time slots "N1", "N2", "N3", and "N4" are arranged in front of the downstream communication time slots. The monitoring time slot "N1" is a time slot 1030 in which the fire alarm 600 with the hop number "2" should transmit a monitoring signal to be received by the fire alarm 600 with the hop number "1". The monitoring time slot "N2" is a time slot 1030 in which the fire alarm 600 with the hop number "3" should transmit a monitoring signal to be received by the fire alarm 600 with the hop number "2". The monitoring time slot "N3" is a time slot 1030 in which the fire alarm 600 with the hop number "4" should transmit a monitoring signal to be received by the fire alarm 600 with the hop number "3". The monitoring time slot "N4" is a time slot 1030 in which the fire alarm 600 with the hop number "5" should transmit a monitoring signal to be received by the fire alarm 600 with the hop number "4".

The monitoring time slots are arranged in the order of "N4", "N3", "N2", and "N1". In other words, the fire alarm 600 with a larger number of hops from the relay device 700 is assigned a monitoring time slot further forward.

The allocation of these time slots 1030 is determined by the relay device 700 or the management device 800. For example, the relay device 700 or the management device 800 determines the allocation of the time slots 1030 based on information on the relay route. The relay device 700 or the management device 800 notifies each fire alarm device 600 of the determined allocation of the time slots 1030. Therefore, each fire alarm device 600 also knows the allocation of these time slots 1030. As a result, the fire alarm device 600 knows the time slots 1030 that should transmit communication signals and that have been assigned to it. The fire alarm device 600 also knows the time slots 1030 in which it can receive communication signals from adjacent fire alarm devices 600 or relay devices 700 on the relay route.

A periodic signal is transmitted in the downstream communication time slot along the relay route shown in Figure 1. The transmission of the periodic signal in downstream communication is performed by broadcast transmission (flooding method). In addition, a response signal is transmitted in the upstream communication time slot along the relay route shown in Figure 1. The transmission of the response signal in upstream communication is performed by unicast transmission.

Figures 6(a)-(b) show the formats of the periodic signal and response signal used in the alarm system 1000. Figure 6(a) shows the format of the periodic signal, that is, the signal periodically transmitted from the relay device 700. As mentioned above, the flooding method is used, so a broadcast address is stored. The synchronization beacon is a flag for TDMA (Time Division Multiple Access) synchronization. The periodic monitoring request flag indicates that it is a periodic signal. No data is stored in the periodic monitoring request.

Figure 6(b) shows the format of the response signal, that is, the signal to be sent when each of the multiple fire alarm devices 600 receives a periodic signal. As mentioned above, unicast communication is used, so the unicast address of the other higher-level fire alarm device 600 or relay device 700 to which the next signal should be sent is stored. The periodic monitoring response flag indicates that it is a response signal. 32 bits are assigned to the periodic monitoring response data, and a maximum of 32 fire alarm devices 600 that can be connected to the alarm system 1000 are expressed by 32 bits. The periodic monitoring response data is generated by logically ORing (XOR) its own information with the information contained in the response signal received from the other lower-level fire alarm device 600. In other words, packets are concatenated. Return to Figure 5.

The triangle marks in FIG. 5 indicate intermittent reception operations performed by the communication unit 620 of the fire alarm 600. In intermittent reception operations in the communication unit 620, reception operations are performed during a portion of the beginning of the time slot 1030, and if no signal (communication signal, monitoring signal) is received during that portion of the period, the reception operation is stopped for the remainder of the time slot 1030. On the other hand, if a signal is received during a portion of the beginning of the time slot 1030, the reception operation continues for the remainder of the time slot 1030. Intermittent reception operations are performed to reduce power consumption.

In downstream communication, the fire alarm device 600 performs intermittent reception only in the time slots 1030 assigned to other higher-level fire alarm devices 600 with which it directly communicates on the relay route. In upstream communication, the fire alarm device 600 performs intermittent reception only in the time slots 1030 assigned to other lower-level fire alarm devices 600 with which it directly communicates on the relay route. Since regular monitoring is performed at predetermined timing, monitoring time slots are not used in upstream communication.

The relay device 700 transmits a periodic signal in time slot 1030 "M" in the downstream communication time slot. As described above, a broadcast address is set in the periodic signal. The first fire alarm device 600a and the second fire alarm device 600b receive the periodic signal in time slot 1030 "M". The second fire alarm device 600b transmits a periodic signal in time slot 1030 "C2". The third fire alarm device 600c receives a periodic signal in time slot 1030 "C2". The third fire alarm device 600c transmits a periodic signal in time slot 1030 "C3". The fourth fire alarm device 600d and the fifth fire alarm device 600e receive a periodic signal in time slot 1030 "C3". The fifth fire alarm device 600e transmits a periodic signal in time slot 1030 "C5". The sixth fire alarm 600f receives a periodic signal in time slot 1030 "C5".

The sixth fire alarm device 600f transmits a response signal in time slot 1030 "C6" in the upstream communication time slot. The fifth fire alarm device 600e receives the response signal in time slot 1030 "C6". The fifth fire alarm device 600e generates a response signal by linking its own response to the response signal from the sixth fire alarm device 600f, and transmits the response signal in time slot 1030 "C5". The third fire alarm device 600c receives the response signal in time slot 1030 "C5".

The fourth fire alarm device 600d transmits a response signal in time slot 1030 "C4". The third fire alarm device 600c receives the response signal in time slot 1030 "C4". The third fire alarm device 600c generates a response signal by combining the response signal from the fifth fire alarm device 600e, the response signal from the fourth fire alarm device 600d, and its own response, and transmits the response signal in time slot 1030 "C3".

The second fire alarm device 600b receives the response signal in time slot 1030 "C3". The second fire alarm device 600b generates a response signal by linking its own response to the response signal from the third fire alarm device 600c, and transmits the response signal in time slot 1030 "C2". The relay device 700 receives the response signal in time slot 1030 "C2". The first fire alarm device 600a transmits a response signal in time slot 1030 "C1". The relay device 700 receives the response signal in time slot 1030 "C1".

The relay device 700 verifies that all of the first fire alarm device 600a through the sixth fire alarm device 600f are alive by checking the response signal received from the first fire alarm device 600a and the response signal received from the second fire alarm device 600b.

When focusing on the fifth fire alarm 600e, the above process is shown as follows. The third fire alarm 600c transmits a periodic signal to the fifth fire alarm 600e in the downstream communication time slot assigned to the third fire alarm 600c. When the fifth fire alarm 600e receives a periodic signal by intermittent reception in the downstream communication time slot assigned to the third fire alarm 600c, it transmits a periodic signal to the sixth fire alarm 600f in the downstream communication time slot assigned to the fifth fire alarm 600e. Here, when the fifth fire alarm 600e receives a periodic signal from the relay device 700 via the third fire alarm 600c, it does not receive a signal from the relay device 700 via the first fire alarm 600a and the fourth fire alarm 600d.

The fifth fire alarm device 600e receives the response signal by intermittent reception in the upstream communication time slot assigned to the sixth fire alarm device 600f. When the fifth fire alarm device 600e receives a regular signal from the third fire alarm device 600c, it transmits a response signal to the third fire alarm device 600c in the upstream communication time slot assigned to the fifth fire alarm device 600e. The response signal from the sixth fire alarm device 600f is also linked to this response signal.

After transmitting a periodic signal to the fifth fire alarm device 600e, the third fire alarm device 600c receives a response signal from the fifth fire alarm device 600e by intermittent reception in the upstream communication time slot assigned to the fifth fire alarm device 600e. The third fire alarm device 600c transmits a response signal in the upstream communication time slot assigned to the third fire alarm device 600c.

Here, if the fifth fire alarm 600e is called the first alarm, the third fire alarm 600c is called the second alarm, the first fire alarm 600a is called the third alarm, and the fourth fire alarm 600d is called the fourth alarm.

Figures 7(a)-(b) show another overview of communications in the alarm system 1000, particularly an overview of "waiting for detection." In Figure 7(a), it is assumed that the fire detection sensor 630 of the sixth fire alarm 600f detects the occurrence of a fire. The processing unit 622 of the sixth fire alarm 600f decides to transmit the detection result. The detection result includes identification information of the sixth fire alarm 600f that detected the fire, as well as information regarding the abnormality. The communication unit 620 of the sixth fire alarm 600f transmits a monitoring signal in the monitoring time slot of the time slot 1030 "N3." The fifth fire alarm 600e receives the monitoring signal in the monitoring time slot of the time slot 1030 "N3."

The fifth fire alarm device 600e transmits a monitoring signal in the monitoring timeslot of time slot 1030 "N2". The third fire alarm device 600c receives a monitoring signal in the monitoring timeslot of time slot 1030 "N2". The third fire alarm device 600c transmits a monitoring signal in the monitoring timeslot of time slot 1030 "N1". The second fire alarm device 600b receives a monitoring signal in the monitoring timeslot of time slot 1030 "N1".

As a result, the monitoring signal is transferred within one frame 1020 from the sixth fire alarm 600f, which is at the lowest side of the multi-hop network, to the second fire alarm 600b, which has a hop count of "1". On the other hand, if the fire detection sensors 630 of all the fire alarms 600 do not detect the occurrence of a fire, the monitoring signal is not transferred.

The sixth fire alarm device 600f transmits the detection result in time slot 1030 "C6" in the upstream communication time slot. The fifth fire alarm device 600e receives the detection result in time slot 1030 "C6". Here, the monitoring unit 626 of the fifth fire alarm device 600e monitors the reception of a monitoring signal in the monitoring time slot "N3" and detects the reception of a monitoring signal, so the fifth fire alarm device 600e performs intermittent reception in time slot 1030 "C6". On the other hand, if the monitoring unit 626 of the fifth fire alarm device 600e does not detect the reception of a monitoring signal, the fifth fire alarm device 600e stops the reception process of the communication signal in time slot 1030 "C6".

The fifth fire alarm device 600e transfers the detection result in time slot 1030 "C5". The third fire alarm device 600c receives the detection result in time slot 1030 "C5". The third fire alarm device 600c transfers the detection result in time slot 1030 "C3". The second fire alarm device 600b receives the detection result in time slot 1030 "C3". The second fire alarm device 600b transfers the detection result in time slot 1030 "C2". The relay device 700 receives the detection result in time slot 1030 "C2".

When the relay device 700 receives the detection result from the second fire alarm device 600b, it transmits the detection result to the management device 800. When the management device 800 receives the detection result, it identifies the fire alarm device 600 to be activated based on the identification information included in the detection result. The correspondence between the identification information and the information of the fire alarm device 600 to be activated is stored in advance in the management device 800. Here, for example, the fifth fire alarm device 600e and the sixth fire alarm device 600f are identified. The management device 800 transmits an instruction to activate the fire alarm to the relay device 700, with the identified fire alarm 600 as the final destination.

In FIG. 7(b), the same process as in FIG. 5 is performed, and the instruction to sound an alarm is transferred in the order of relay device 700, second fire alarm 600b, third fire alarm 600c, fifth fire alarm 600e, and sixth fire alarm 600f. When the communication units 620 of the fifth fire alarm 600e and sixth fire alarm 600f receive the instruction to sound an alarm, the control unit 624 causes the buzzer 632 to sound. The control unit 624 may also cause the light-emitting device to flash.

(2) Routing Up to now, it is assumed that a relay route as shown in Fig. 1 has been formed, but here, the formation and change of a relay route will be described with reference to Fig. 8 as well. Fig. 8 shows an overview of routing in the alarm system 1000. Fig. 8 shows the n+1 fire alarm 600n+1, the n+2 fire alarm 600n+2, the n+3 fire alarm 600n+3, and the relay device 700 of the alarm system 1000. The n+1 fire alarm 600n+1, the n+2 fire alarm 600n+2, and the n+3 fire alarm 600n+3 correspond to any of the fire alarms 600 in Fig. 1. Around the n+3 fire alarm 600n+3, there may be a fire alarm 600 other than the n+1 fire alarm 600n+1 and the n+2 fire alarm 600n+2, for example, the n+4 fire alarm 600n+4 (not shown).

Figure 9 is a sequence diagram showing the routing procedure in the alarm system 1000. Here, the routing process will be explained focusing on the (n+3)th fire alarm device 600n+3. Each fire alarm device 600 broadcasts a HELLO message at regular intervals. The HELLO message includes route quality information from the fire alarm device 600 to the relay device 700. The communication unit 620 of the (n+3)th fire alarm device 600n+3 receives HELLO messages from the (n+1)th fire alarm device 600n+1, the (n+2)th fire alarm device 600n+2, and the (n+4)th fire alarm device 600n+4 (S10, S12, S14).

The communication unit 620 of the n+3th fire alarm device 600n+3 measures the received power of each received HELLO message, and the processing unit 622 derives the link quality for each fire alarm device 600 based on the measured received power. The link quality is a value that changes according to the received power and decreases as the received power increases. The above-mentioned route quality is also indicated in the same manner as the link quality. The control unit 624 derives the tentative route cost by adding the link quality of the n+1th fire alarm device 600n+1 and the route quality included in the HELLO message from the n+1th fire alarm device 600n+1 as follows:
Tentative route cost = route quality + Ka × link quality + Kb × C Formula (1)
Here, Ka and Kb are coefficients, and C is a predetermined constant. If Kb is set to "0" when forming a relay route, Kb x C is ignored.

The control unit 624 also derives tentative route costs for the other fire alarm devices 600. The control unit 624 compares multiple tentative route costs and selects several fire alarm devices 600 in order of lowest tentative route cost as priority link destinations. Here, for example, the n+1th fire alarm device 600n+1 and the n+2nd fire alarm device 600n+2 are selected as priority link destinations.

The communication unit 620 of the (n+3)th fire alarm 600n+3 transmits the address of the selected fire alarm 600 and the link quality at the time of reception in a LINK_REQ sub-message of the HELLO message (S16, S18). The (n+1)th fire alarm 600n+1 and (n+2)th fire alarm 600n+2 transmit the link quality in the opposite direction in a LINK_REP sub-message (S20, 22).

The communication unit 620 of the (n+3)th fire alarm device 600n+3 receives the LINK_REP sub-message. The control unit 624 of the (n+3)th fire alarm device 600n+3 compares the link quality included in the LINK_REP sub-message from the (n+1)th fire alarm device 600n+1 with the link quality derived based on the already measured received power, and selects the larger link quality. The control unit 624 also derives the formal route cost by adding the selected link quality and the route quality for the (n+1)th fire alarm device 600n+1 as follows:
Formal route cost = route quality + Ka × Max (link quality) + Kb × C Equation (2)
Here, Max denotes selecting the maximum link quality.

The control unit 624 also derives the official route cost for the n+2th fire alarm 600n+2. The control unit 624 compares the official route cost for the n+1th fire alarm 600n+1 with the official route cost for the n+2th fire alarm 600n+2, and selects the smaller one as the relay route. The relay route that is not selected may be used as an alternative route.

That is, the n+3 fire alarm device 600n+3 derives a formal route cost (hereinafter referred to as the "first cost") for a relay route (hereinafter referred to as the "first relay route") for communicating with the relay device 700 via the n+1 fire alarm device 600n+1 by exchanging link quality information with the n+1 fire alarm device 600n+1. The n+3 fire alarm device 600n+3 also derives a formal route cost (hereinafter referred to as the "second relay route") for communicating with the relay device 700 via the n+2 fire alarm device 600n+2 by exchanging link quality information with the n+2 fire alarm device 600n+2. Furthermore, the n+3 fire alarm device 600n+3 preferentially selects the relay route that is smaller than the first cost and the second cost. A relay route is formed by performing such processing in each fire alarm device 600. Information about the relay route (alternative route) formed in each fire alarm 600 is transmitted to the management device 800 via the relay device 700. The management device 800 determines the allocation of the time slot 1030 according to the number of hops based on the information about the relay route (alternative route).

(3) Occurrence of communication failure Figures 10(a)-(b) show a situation in which a communication failure occurs in the alarm system 1000. Figure 10(a) assumes a situation in which an obstacle such as an iron door (not shown) is present between the third fire alarm device 600c and the fifth fire alarm device 600e in the alarm system 1000 of Figure 1. The presence of such an obstacle deteriorates the communication environment between the third fire alarm device 600c and the fifth fire alarm device 600e.

Figure 10(b) shows an overview of communications in the situation of Figure 10(a), particularly an overview of "regular monitoring". The relay device 700 transmits a regular signal in time slot 1030 "M" in the downstream communication time slot. The first fire alarm device 600a and the second fire alarm device 600b receive the regular signal in time slot 1030 "M". The second fire alarm device 600b transmits a regular signal in time slot 1030 "C2". The third fire alarm device 600c receives the regular signal in time slot 1030 "C2". The third fire alarm device 600c transmits a regular signal in time slot 1030 "C3". The fourth fire alarm device 600d and the fifth fire alarm device 600e perform intermittent reception in time slot 1030 "C3". The fourth fire alarm device 600d receives the regular signal, but the fifth fire alarm device 600e fails to receive the regular signal. As a result, the periodic signal is not received by the sixth fire alarm 600f either.

The fourth fire alarm device 600d transmits a response signal in time slot 1030 "C4" in the upstream communication time slot. The third fire alarm device 600c receives the response signal in time slot 1030 "C4". The third fire alarm device 600c generates a response signal by linking its own response to the response signal from the fourth fire alarm device 600d, and transmits the response signal in time slot 1030 "C3".

The second fire alarm device 600b receives the response signal in time slot 1030 "C3". The second fire alarm device 600b generates a response signal by linking its own response to the response signal from the third fire alarm device 600c, and transmits the response signal in time slot 1030 "C2". The relay device 700 receives the response signal in time slot 1030 "C2". The first fire alarm device 600a transmits a response signal in time slot 1030 "C1". The relay device 700 receives the response signal in time slot 1030 "C1".

The relay device 700 confirms that the first fire alarm device 600a to the fourth fire alarm device 600d are alive by checking the response signal received from the first fire alarm device 600a and the response signal received from the second fire alarm device 600b. The relay device 700 also confirms that there is no response from the fifth fire alarm device 600e and the sixth fire alarm device 600f. Following this, the relay device 700 retransmits the periodic signal in the next frame 1020 as shown in FIG. 3(e). At that time, the relay device 700 uses the relay route (FIG. 1) that transmitted the initial periodic signal. In addition, the monitoring time slot is also used in the upstream communication. If there is no response from any of the fire alarm devices 600 even after such retransmission of the periodic signal, the relay device 700 repeats retransmission of the periodic signal via the same relay route. On the other hand, if the relay device 700 confirms that all the fire alarm devices 600 are alive, "detection waiting" is executed from the next frame 1020.

(4) Retransmission on a new route (part 1)
If there is a fire alarm 600 that does not respond even after multiple transmissions of a periodic signal via the same relay route, it is necessary to switch the relay route. In this embodiment, (4) retransmission on a new route (part 1) or (5) retransmission on a new route (part 2) is executed. Here, (4) retransmission on a new route (part 1) will be described.

Figures 11(a)-(b) show an overview of retransmission in the alarm system 1000. Figure 11(a) shows the situation following Figure 10(a). Until now, the fifth fire alarm device 600e has used a relay route via the third fire alarm device 600c as a relay route toward the relay device 700. However, in the situation of Figure 10(a), the fifth fire alarm device 600e fails to receive a regular signal from the relay device 700 via the third fire alarm device 600c. In the frame 1020 shown as another route retransmission in Figure 3(e), the control unit 624 of the fifth fire alarm device 600e causes the communication unit 620 to perform intermittent reception in all time slots 1030 (except for the time slot 1030 assigned to the fifth fire alarm device 600e) in the downstream communication time slot. As a result, the communication unit 620 receives the periodic signal from the first fire alarm device 600a and the periodic signal from the fourth fire alarm device 600d. The control unit 624 transmits the periodic signal to the sixth fire alarm device 600f in the time slot 1030 assigned to the fifth fire alarm device 600e.

The control unit 624 compares the communication quality of the periodic signal received from the first fire alarm device 600a with the communication quality of the periodic signal received from the fourth fire alarm device 600d. An example of communication quality is RSSI (Received Signal Strength Indicator). The control unit 624 selects the fire alarm device 600 that transmitted the periodic signal with the larger RSSI, that is, the better communication quality. This corresponds to selecting the fire alarm device 600 that transmitted the periodic signal with the smaller link quality. In FIG. 11(a), for example, the first fire alarm device 600a is selected. The control unit 624 decides to switch to a relay route that passes through the first fire alarm device 600a as the relay route toward the relay device 700. The relay route to be switched to can be said to be an alternative route. The communication unit 620 transmits a response signal to the relay device 700 to the first fire alarm device 600a.

Figure 11 (b) shows an overview of communication in the situation of Figure 11 (a), particularly an overview of "another route retransmission". The relay device 700 transmits a periodic signal in time slot 1030 "M" in the downstream communication time slot. The first fire alarm device 600a and the second fire alarm device 600b receive the periodic signal in time slot 1030 "M". The first fire alarm device 600a transmits a periodic signal in time slot 1030 "C1". The fifth fire alarm device 600e receives a periodic signal in time slot 1030 "C1". The second fire alarm device 600b transmits a periodic signal in time slot 1030 "C2". The third fire alarm device 600c receives a periodic signal in time slot 1030 "C2". The third fire alarm device 600c transmits a periodic signal in time slot 1030 "C3".

The fourth fire alarm device 600d and the fifth fire alarm device 600e perform intermittent reception in time slot 1030 "C3". The fourth fire alarm device 600d receives the periodic signal, but the fifth fire alarm device 600e fails to receive the periodic signal. The fourth fire alarm device 600d transmits a periodic signal in time slot 1030 "C4". The fifth fire alarm device 600e receives the periodic signal in time slot 1030 "C4".

As a result of the above processing, the fifth fire alarm device 600e receives the periodic signal from the first fire alarm device 600a and the periodic signal from the fourth fire alarm device 600d by performing intermittent reception in time slots 1030 "C1" to "C4". As described above, the fifth fire alarm device 600e selects the relay route that passes through the first fire alarm device 600a as an alternative route to the relay device 700. The fifth fire alarm device 600e transmits the periodic signal in time slot 1030 "C5". The sixth fire alarm device 600f receives the periodic signal in time slot 1030 "C5".

The sixth fire alarm device 600f transmits a monitoring signal in the monitoring timeslot of time slot 1030 "N3". The fifth fire alarm device 600e receives a monitoring signal in the monitoring timeslot of time slot 1030 "N3". The fourth fire alarm device 600d transmits a monitoring signal in the monitoring timeslot of time slot 1030 "N2". The third fire alarm device 600c receives a monitoring signal in the monitoring timeslot of time slot 1030 "N2".

The third fire alarm 600c transmits a monitoring signal in the monitoring time slot of time slot 1030 "N1". The fifth fire alarm 600e transmits a monitoring signal in the monitoring time slot of time slot 1030 "N1". The first fire alarm 600a and the second fire alarm 600b receive the monitoring signal in the monitoring time slot of time slot 1030 "N1". As a result, the monitoring signal is transferred within one frame 1020 from the sixth fire alarm 600f, which is at the lowest side of the multi-hop network, to the first fire alarm 600a and the second fire alarm 600b, which have a hop count of "1".

The sixth fire alarm device 600f transmits a response signal in time slot 1030 "C6" in the upstream communication time slot. The fifth fire alarm device 600e receives the response signal in time slot 1030 "C6". The fifth fire alarm device 600e transmits a response signal in time slot 1030 "C5". The response signal is the same as before, so a description will be omitted here. The first fire alarm device 600a receives the response signal in time slot 1030 "C5".

The fourth fire alarm device 600d transmits a response signal in time slot 1030 "C4" in the upstream communication time slot. The third fire alarm device 600c receives the response signal in time slot 1030 "C4". The third fire alarm device 600c transmits a response signal in time slot 1030 "C3". The second fire alarm device 600b receives the response signal in time slot 1030 "C3". The second fire alarm device 600b transmits a response signal in time slot 1030 "C2". The relay device 700 receives the response signal in time slot 1030 "C2". The first fire alarm device 600a transmits a response signal in time slot 1030 "C1". The relay device 700 receives the response signal in time slot 1030 "C1".

The relay device 700 confirms that all of the first fire alarm device 600a to the sixth fire alarm device 600f are alive by checking the response signal received from the first fire alarm device 600a and the response signal received from the second fire alarm device 600b. Through this process, the route information stored in the relay device 700 and each fire alarm device 600, i.e., the routing information, corresponds to the relay route in FIG. 1 (hereinafter referred to as the "main route"), but by using a monitoring signal, a notification signal and a response signal are transmitted along an alternative route. In other words, when a notification signal is transmitted along an alternative route, a response signal is also transmitted along the alternative route. The alternative route is the relay route with the best communication quality in the fifth fire alarm device 600e, and therefore can be said to be a highly reliable relay route.

(5) Retransmission on a new route (part 2)
12(a)-(b) show another overview of retransmission in the alarm system 1000. FIG. 12(a) shows a situation following FIG. 10(a). Up until now, the fifth fire alarm device 600e has used a relay route via the third fire alarm device 600c as a relay route toward the relay device 700. However, in the situation of FIG. 10(a), the fifth fire alarm device 600e fails to receive a regular signal from the relay device 700 via the third fire alarm device 600c. Meanwhile, the control unit 624 of the fifth fire alarm device 600e derives link quality to other surrounding fire alarm devices 600 when performing the above-mentioned routing process. The link quality may be derived periodically even after the routing process is completed. For example, link quality to the first fire alarm device 600a, the third fire alarm device 600c, and the fourth fire alarm device 600d is derived.

In frame 1020 indicated as "another route retransmission" in FIG. 3(e), the control unit 624 of the fifth fire alarm device 600e compares the link quality for each fire alarm device 600 and selects the other fire alarm device 600 with the lowest link quality, excluding the third fire alarm device 600c. This is equivalent to selecting the other fire alarm device 600 with the highest communication quality, excluding the third fire alarm device 600c. Here, the first fire alarm device 600a is selected as an example. The control unit 624 causes the communication unit 620 to perform intermittent reception in the time slot 1030 assigned to the first fire alarm device 600a in the downstream communication time slot. As a result, the communication unit 620 receives a periodic signal from the first fire alarm device 600a. In other words, if the fifth fire alarm device 600e fails to receive a periodic signal from the third fire alarm device 600c, and the link quality with the first fire alarm device 600a is better than the link quality with the fourth fire alarm device 600d, the fifth fire alarm device 600e receives a periodic signal via the first fire alarm device 600a. The fifth fire alarm device 600e does not receive a periodic signal from the fourth fire alarm device 600d. The control unit 624 transmits a periodic signal to the sixth fire alarm device 600f in the time slot 1030 assigned to the fifth fire alarm device 600e.

The control unit 624 determines a relay route that passes through the first fire alarm device 600a as an alternative route to the relay device 700. The communication unit 620 transmits a response signal to the relay device 700 to the first fire alarm device 600a. In other words, when the fifth fire alarm device 600e receives a periodic signal from the first fire alarm device 600a, it transmits a response signal to the first fire alarm device 600a.

Figure 12(b) shows an overview of communications in the situation of Figure 12(a), particularly an overview of "another route retransmission". The fifth fire alarm device 600e in Figure 11(b) performs intermittent reception in timeslots 1030 "C1" to "C4" and "C6" in the downstream communication timeslot. On the other hand, the fifth fire alarm device 600e in Figure 12(b) performs intermittent reception in timeslot 1030 "C1" in the downstream communication timeslot, but does not perform intermittent reception in timeslots 1030 "C2" to "C4" and "C6". Other than that, it is the same as Figure 11(b), so a description will be omitted here.

(6) Notification of route change (4) Retransmission along a new route (part 1) or (5) Retransmission along a new route (part 2) enables communication along an alternative route even if communication along the original route fails. Following this, the alarm system 1000 changes the alternative route to the original route.

Figures 13(a)-(b) show an overview of notifications in the alarm system 1000. Figure 13(a) shows a situation following Figure 11(a) or Figure 12(a). When the fifth fire alarm device 600e switches the relay route including the third fire alarm device 600c to a relay route including the first fire alarm device 600a, it transmits a route switching notification to the first fire alarm device 600a to inform the relay device 700 of the relay route switching. The route switching notification indicates, for example, that the third fire alarm device 600c has been switched to the first fire alarm device 600a. The route switching notification is received by the relay device 700 via the first fire alarm device 600a.

Figure 13 (b) shows an overview of communication in the situation of Figure 13 (a). The fifth fire alarm device 600e, which generated the route switching notification, transmits a monitoring signal in the monitoring time slot of time slot 1030 "N1". The first fire alarm device 600a receives the monitoring signal in the monitoring time slot of time slot 1030 "N1". The fifth fire alarm device 600e transmits a route switching notification in time slot 1030 "C5". The first fire alarm device 600a, which received the route switching notification in time slot 1030 "C5", transmits a route switching notification in time slot 1030 "C1". The relay device 700 receives the route switching notification in time slot 1030 "C1".

The control unit 720 of the relay device 700 updates the relay route of the alarm system 1000 based on the route switching notification received from the first fire alarm device 600a. As a result, the relay route managed by the relay device 700 is updated from FIG. 1 to FIG. 12(a). By updating the relay route in this way, the number of hops from the fifth fire alarm device 600e to the relay device 700 is changed from "3" to "2", and the number of hops from the sixth fire alarm device 600f to the relay device 700 is changed from "4" to "3".

(7) Slot switching and aging When there is a fire alarm device 600 whose number of hops to the relay device 700 is changed due to an update of the relay route, it becomes necessary to change the allocation of the communication time slot. The allocation unit 722 of the relay device 700 determines the change of the allocation of the fire alarm device 600 to the downstream communication time slot and the upstream communication time slot according to the number of hops. When the control unit 720 determines the change of the allocation of the fire alarm device 600 to the downstream communication time slot and the upstream communication time slot, it generates slot information indicating the changed allocation. The output unit 712 outputs the slot information to the multiple fire alarm devices 600. The slot information is transmitted, for example, by the downstream communication time slot before the change of the allocation. Each fire alarm device 600 that receives the slot information recognizes the downstream communication time slot and the upstream communication time slot that are assigned to it. After that, the allocation of the fire alarm device 600 to the downstream communication time slot and the upstream communication time slot is actually changed.

Each fire alarm 600 recognizes the change in the time slots for downstream communication and the time slots for upstream communication, but does not recognize the changed relay route. Therefore, each fire alarm 600 also performs intermittent reception in the time slots 1030 assigned to other fire alarms 600 that were connected on the relay route before the change, but that are not connected on the relay route after the change. Since such intermittent reception is a wasteful process, it is desirable to update the relay route. Each fire alarm 600 performs an aging process to forget the relay route before the change and to remember the relay route after the change.

Figures 14(a)-(b) show an overview of slot switching and aging in the alarm system 1000. Figure 14(a) shows a situation following Figure 13(a). The allocation of the fire alarm device 600 to the downstream communication time slot and the upstream communication time slot has been changed, but the relay route is shown in the same way as in Figure 13(a). In this relay route, the fire alarm device 600 that has decided to change the relay route is the fifth fire alarm device 600e. In addition, in the changed relay route, the upper fire alarm device 600 that is newly connected to the fifth fire alarm device 600e is the first fire alarm device 600a. In addition, in the changed relay route, the fire alarm device 600 that is disconnected from the fifth fire alarm device 600e is the third fire alarm device 600c.

The aging process is performed in "regular monitoring". The fifth fire alarm 600e receives a regular signal in the downstream communication time slot assigned to the first fire alarm 600a. Furthermore, when the fifth fire alarm 600e receives a regular signal, it transmits a response signal to the first fire alarm 600a in the upstream communication time slot assigned to the fifth fire alarm 600e. At that time, the next destination of the response signal is set to the first fire alarm 600a. After transmitting a response signal to the first fire alarm 600a, if the fifth fire alarm 600e does not receive a retransmission of the regular signal from the relay device 700, it switches the upper side from the third fire alarm 600c to the first fire alarm 600a. This corresponds to switching the reception of a regular signal in the downstream communication time slot assigned to the third fire alarm 600c to the reception of a regular signal in the downstream communication time slot assigned to the first fire alarm 600a.

The third fire alarm 600c transmits a periodic signal to the fifth fire alarm 600e. If the third fire alarm 600c does not receive a response signal from the fifth fire alarm 600e in the upstream communication time slot assigned to the fifth fire alarm 600e after transmitting the periodic signal, and if it does not subsequently receive a retransmission of the periodic signal from the relay device 700, it deletes the fifth fire alarm 600e on the lower side. This corresponds to not transmitting a periodic signal to the fifth fire alarm 600e in the downstream communication time slot assigned to the third fire alarm 600c, and not receiving a response signal in the upstream communication time slot assigned to the fifth fire alarm 600e.

When the first fire alarm 600a receives a response signal from the fifth fire alarm 600e in the upstream communication time slot assigned to the fifth fire alarm 600e in a situation where the first fire alarm 600a has not received a response signal from the fifth fire alarm 600e in the upstream communication time slot assigned to the fifth fire alarm 600e, the first fire alarm 600a transmits a response signal in the upstream communication time slot assigned to the first fire alarm 600a. Subsequently, if the first fire alarm 600a does not receive a retransmission of the periodic signal from the relay device 700, the fifth fire alarm 600e is added to the lower side. This is equivalent to transmitting a periodic signal to the fifth fire alarm 600e in the downstream communication time slot assigned to the first fire alarm 600a.

Figure 14 (b) shows an overview of communication in the situation of Figure 14 (a), particularly during aging processing. Due to the change in the relay route, the number of hops for the fifth fire alarm 600e and the sixth fire alarm 600f has been changed. Therefore, the relay device 700, the first fire alarm 600a, the second fire alarm 600b, the third fire alarm 600c, the fifth fire alarm 600e, the fourth fire alarm 600d, and the sixth fire alarm 600f are assigned to the downstream communication time slot in order from the front. In addition, the sixth fire alarm 600f, the fourth fire alarm 600d, the fifth fire alarm 600e, the third fire alarm 600c, the second fire alarm 600b, the first fire alarm 600a, and the relay device 700 are assigned to the upstream communication time slot in order from the front.

The relay device 700 transmits a periodic signal in time slot 1030 "M" in the downstream communication time slot. The first fire alarm device 600a and the second fire alarm device 600b receive the periodic signal in time slot 1030 "M". The first fire alarm device 600a transmits a periodic signal in time slot 1030 "C1". The fifth fire alarm device 600e receives a periodic signal in time slot 1030 "C1". The second fire alarm device 600b transmits a periodic signal in time slot 1030 "C2". The third fire alarm device 600c receives a periodic signal in time slot 1030 "C2". The third fire alarm device 600c transmits a periodic signal in time slot 1030 "C3".

The fourth fire alarm device 600d and the fifth fire alarm device 600e perform intermittent reception in time slot 1030 "C3". The fourth fire alarm device 600d receives the periodic signal, but the fifth fire alarm device 600e fails to receive the periodic signal. The fifth fire alarm device 600e transmits a periodic signal in time slot 1030 "C5". The sixth fire alarm device 600f receives the periodic signal in time slot 1030 "C5".

The fourth fire alarm device 600d and the sixth fire alarm device 600f transmit a monitoring signal in the monitoring time slot of time slot 1030 "N2". The third fire alarm device 600c and the fifth fire alarm device 600e receive a monitoring signal in the monitoring time slot of time slot 1030 "N2". The third fire alarm device 600c and the fifth fire alarm device 600e transmit a monitoring signal in the monitoring time slot of time slot 1030 "N1". The first fire alarm device 600a and the second fire alarm device 600b receive a monitoring signal in the monitoring time slot of time slot 1030 "N2".

The sixth fire alarm device 600f transmits a response signal in time slot 1030 "C6" in the time slot for upstream communication. The fifth fire alarm device 600e receives the response signal in time slot 1030 "C6". The fourth fire alarm device 600d transmits a response signal in time slot 1030 "C4" in the time slot for upstream communication. The third fire alarm device 600c receives the response signal in time slot 1030 "C4".

The fifth fire alarm device 600e transmits a response signal in the time slot 1030 "C5". The response signal is the same as before, so a description is omitted here. The first fire alarm device 600a receives a response signal in the time slot 1030 "C5". The third fire alarm device 600c transmits a response signal in the time slot 1030 "C3". The second fire alarm device 600b receives a response signal in the time slot 1030 "C3". The second fire alarm device 600b transmits a response signal in the time slot 1030 "C2". The relay device 700 receives the response signal in the time slot 1030 "C2". The first fire alarm device 600a transmits a response signal in the time slot 1030 "C1". The relay device 700 receives the response signal in the time slot 1030 "C1".

The relay device 700 confirms that all of the first fire alarm device 600a to the sixth fire alarm device 600f are alive by checking the response signal received from the first fire alarm device 600a and the response signal received from the second fire alarm device 600b. As a result, the relay device 700 does not resend the periodic signal. Through this process, the aging conditions are met in each fire alarm device 600, and the relay route before the change is erased.

(8) Communication after route switching Aging causes the alternative route to become the main route. Figures 15(a)-(b) show an overview of communication after route switching in the alarm system 1000. Figure 15(a) shows a situation following Figure 14(a). This corresponds to after aging processing. Figure 15(b) shows an overview of communication in the situation of Figure 15(a), particularly an overview of "regular monitoring". The relay device 700 transmits a regular signal in the time slot 1030 "M" in the downstream communication time slot. The first fire alarm device 600a and the second fire alarm device 600b receive a regular signal in the time slot 1030 "M". The first fire alarm device 600a transmits a regular signal in the time slot 1030 "C1". The fifth fire alarm device 600e receives a regular signal in the time slot 1030 "C1". The second fire alarm device 600b transmits a regular signal in the time slot 1030 "C2". The third fire alarm device 600c receives a periodic signal in the time slot 1030 "C2". The third fire alarm device 600c transmits a periodic signal in the time slot 1030 "C3". The fourth fire alarm device 600d receives a periodic signal in the time slot 1030 "C3". The fifth fire alarm device 600e transmits a periodic signal in the time slot 1030 "C5". The sixth fire alarm device 600f receives a periodic signal in the time slot 1030 "C5".

The sixth fire alarm device 600f transmits a response signal in time slot 1030 "C6" in the upstream communication time slot. The fifth fire alarm device 600e receives a response signal in time slot 1030 "C6". The fourth fire alarm device 600d transmits a response signal in time slot 1030 "C4" in the upstream communication time slot. The third fire alarm device 600c receives a response signal in time slot 1030 "C4". The fifth fire alarm device 600e transmits a response signal in time slot 1030 "C5". The response signals are the same as before, so a description will be omitted here. The first fire alarm device 600a receives a response signal in time slot 1030 "C5".

The third fire alarm device 600c transmits a response signal in time slot 1030 "C3". The second fire alarm device 600b receives the response signal in time slot 1030 "C3". The second fire alarm device 600b transmits a response signal in time slot 1030 "C2". The relay device 700 receives the response signal in time slot 1030 "C2". The first fire alarm device 600a transmits a response signal in time slot 1030 "C1". The relay device 700 receives the response signal in time slot 1030 "C1". Since the relay route has been switched and regular monitoring is performed at a predetermined timing, the monitoring time slot is not used in the upstream communication.

The subject of the device, system, or method of the present disclosure includes a computer. The computer executes a program to realize the function of the subject of the device, system, or method of the present disclosure. The computer includes a processor that operates according to the program as the main hardware configuration. The type of processor is not important as long as it can realize the function by executing the program. The processor is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or an LSI (Large Scale Integration). The multiple electronic circuits may be integrated into one chip or may be provided on multiple chips. The multiple chips may be integrated into one device or may be provided on multiple devices. The program is recorded on a non-transitory recording medium such as a computer-readable ROM, optical disk, or hard disk drive. The program may be stored in the recording medium in advance, or may be supplied to the recording medium via a wide area communication network including the Internet.

According to this embodiment, since it is possible to receive signals from each of the multiple alarm devices, multiple relay routes can be secured. Furthermore, since multiple relay routes are secured, communication reliability can be improved even during constant communication failures. Furthermore, since multiple relay routes are secured, relay routes can be smoothly switched in a multi-hop network. Furthermore, when a signal is being received from a connected fire alarm device 600, signals from other fire alarm devices 600 are not received, so an increase in power consumption can be suppressed. Furthermore, if reception of a signal from a connected fire alarm device 600 fails, signals from other fire alarm devices 600 are received, so relay routes can be smoothly switched in a multi-hop network.

In addition, since it is possible to receive signals from two or more other unconnected fire alarm devices 600, communication reliability can be further improved even during constant communication failures. In addition, since it is possible to receive signals from two or more other unconnected fire alarm devices 600, relay routes can be smoothly switched in a multi-hop network. In addition, since it is possible to receive signals from two or more other unconnected fire alarm devices 600, if reception of a signal from a connected fire alarm device 600 fails, a signal from the other fire alarm device 600 with better link quality is received, so relay routes can be smoothly switched in a multi-hop network. In addition, since it is possible to receive signals from two or more other unconnected fire alarm devices 600, if reception of a signal from a connected fire alarm device 600 fails, a signal from the other fire alarm device 600 with better link quality is received, so relay route switching can be efficiently executed. In addition, since an upstream signal is transmitted to a fire alarm device 600 that has received a downstream signal, the reliability of upstream communication can be improved.

In addition, when the relay route is switched, a route switching notification is transmitted to notify the relay device 700 of the switch of the relay route, so that the relay route can be switched smoothly in the multi-hop network. Furthermore, if a retransmission of a periodic signal from the relay device 700 is not received after a response signal is transmitted to the new fire alarm device 600, reception of a periodic signal in the downstream communication time slot assigned to the original fire alarm device 600 is switched to reception of a periodic signal in the downstream communication time slot assigned to the third new fire alarm device 600, so that unnecessary reception processing can be stopped. Furthermore, because unnecessary reception processing is stopped, an increase in power consumption can be suppressed.

In addition, if a response signal is not received in the upstream communication time slot assigned to the fire alarm 600 after a periodic signal is transmitted to the fire alarm 600, and a retransmission of the periodic signal from the relay device 700 is not received, communication is not performed in the downstream communication time slot and the upstream communication time slot assigned to the fire alarm 600, so unnecessary communication processing can be stopped. Furthermore, since unnecessary communication processing is stopped, an increase in power consumption can be suppressed. Furthermore, when a response signal is received from a fire alarm 600 from which a response signal has not been received, a response signal is transmitted, and if a retransmission of the periodic signal from the relay device 700 is not received, a periodic signal is transmitted to the fire alarm 600, so that the relay route can be smoothly switched in the multi-hop network.

Furthermore, the fire alarm 600 with a smaller number of hops to the relay device 700 is assigned an earlier downstream communication time slot, so that transfer can be completed within frame 1020.Furthermore, the fire alarm 600 with a larger number of hops to the relay device 700 is assigned an earlier upstream communication time slot, so that transfer can be completed within frame 1020.Furthermore, when a route switching notification is received, if the allocation of the fire alarm 600 to the downstream communication time slot and the upstream communication time slot is changed, the slot information is transmitted, so that the change in allocation can be notified.

An overview of one aspect of the present disclosure may be summarized as follows.
(Item 1-1)
The system comprises a plurality of alarm devices (600) that form a multi-hop network extending from a relay device (700),
The plurality of alarm devices (600) include a first alarm device (600e), a second alarm device (600c), and a third alarm device (600a),
The first alarm device (600e) receives a signal from the relay device (700) via the second alarm device (600c),
The first alarm device (600e) is also able to receive a signal from the relay device (700) via the third alarm device (600a).
Alarm system (1000).

(Item 1-2)
When a signal is received from the relay device (700) via the second alarm device (600c), the first alarm device (600e) does not receive a signal from the relay device (700) via the third alarm device (600a),
If the first alarm device (600e) fails to receive a signal from the relay device (700) via the second alarm device (600c), it receives a signal from the relay device (700) via the third alarm device (600a) (the alarm system (1000) described in Item 1-1).

(Item 1-3)
The plurality of alarms (600) also includes a fourth alarm (600d),
the first alarm device (600e) is also able to receive a signal from the relay device (700) via the fourth alarm device (600d),
When a signal is received from the relay device (700) via the second alarm device (600c), the first alarm device (600e) does not receive a signal from the relay device (700) via the fourth alarm device (600d),
If the first alarm device (600e) fails to receive a signal from the relay device (700) via the second alarm device (600c), it receives a signal from the relay device (700) via the third alarm device (600a), and receives a signal from the relay device (700) via the fourth alarm device (600d) (the alarm system (1000) described in item 1-2).

(Item 1-4)
The plurality of alarms (600) also includes a fourth alarm (600d),
the first alarm device (600e) is also able to receive a signal from the relay device (700) via the fourth alarm device (600d),
When a signal is received from the relay device (700) via the second alarm device (600c), the first alarm device (600e) does not receive a signal from the relay device (700) via the fourth alarm device (600d),
If the first alarm device (600e) fails to receive a signal from the relay device (700) via the second alarm device (600c), and the link quality with the third alarm device (600a) is better than the link quality with the fourth alarm device (600d), then the first alarm device (600e) will receive a signal from the relay device (700) via the third alarm device (600a), but will not receive a signal from the relay device (700) via the fourth alarm device (600d) (the alarm system (1000) described in item 1-2).

(Item 1-5)
When the first alarm device (600e) receives a signal from the relay device (700) via the second alarm device (600c), it transmits a signal for the relay device (700) to the second alarm device (600c),
The alarm system (1000) described in any one of items 1-1) to 1-3, wherein, when the first alarm device (600e) receives a signal from the relay device (700) via the third alarm device (600a), it transmits a signal for the relay device (700) to the third alarm device (600a).

(Item 1-6)
An alarm device (600) out of a plurality of alarm devices (600) constituting a multi-hop network spreading out from a relay device (700),
When this alarm device (600) is referred to as the first alarm device (600e), the multiple alarm devices (600) also include a second alarm device (600c) and a third alarm device (600a),
a communication section (620) that receives a signal from the relay device (700) via the second alarm device (600c) and is also capable of receiving a signal from the relay device (700) via the third alarm device (600a);
A control unit (624) that controls the communication unit (620);
An alarm (600) comprising:

(Item 1-7)
A communication method in an alarm device (600) out of a plurality of alarm devices (600) that make up a multi-hop network spreading out from a relay device (700), comprising:
When this alarm device (600) is referred to as the first alarm device (600e), the multiple alarm devices (600) also include a second alarm device (600c) and a third alarm device (600a),
receiving a signal from the relay device (700) via the second alarm device (600c);
a step of being able to receive a signal from the relay device (700) also via the third alarm device (600a);
A communication method comprising:

(Item 1-8)
A program to be executed by an alarm device (600) out of a plurality of alarm devices (600) constituting a multi-hop network extending from a relay device (700),
When this alarm device (600) is referred to as the first alarm device (600e), the multiple alarm devices (600) also include a second alarm device (600c) and a third alarm device (600a),
receiving a signal from the relay device (700) via the second alarm device (600c);
and a step of being able to receive a signal from the relay device (700) also via the third alarm device (600a).

(Item 2-1)
The system comprises a plurality of alarm devices (600) that form a multi-hop network extending from a relay device (700),
The plurality of alarm devices (600) include a first alarm device (600e), a second alarm device (600c), and a third alarm device (600a),
The first alarm device (600e) receives a signal from the relay device (700) via the second alarm device (600c),
When the first alarm device (600e) fails to receive a signal from the relay device (700) via the second alarm device (600c), it receives a signal from the relay device (700) via the third alarm device (600a),
When the first alarm device (600e) switches a relay route including the second alarm device (600c) to a relay route including the third alarm device (600a), it transmits a route switching notification to the third alarm device (600a) to notify the relay device (700) of the relay route switching.
Alarm system (1000).

(Item 2-2)
A plurality of downstream communication time slots to be assigned to each of the plurality of alarm devices (600) are arranged on a time axis in order to transmit a signal from the relay device (700);
A plurality of upstream communication time slots to be assigned to each of the plurality of alarm devices (600) are arranged on a time axis in order to transmit a signal to the relay device (700);
The signal from the relay device (700) is a periodic signal that is periodically transmitted from the relay device (700),
the signal to the relay device (700) is a response signal to be transmitted when each of the multiple alarm devices (600) receives the periodic signal,
When the first alarm device (600e) receives the periodic signal in the downstream communication timeslot allocated to the second alarm device (600c), it transmits the response signal to the second alarm device (600c) in the upstream communication timeslot allocated to the first alarm device (600e),
when the first alarm device (600e) fails to receive the periodic signal in the downstream communication timeslot allocated to the second alarm device (600c), it receives the periodic signal in the downstream communication timeslot allocated to the third alarm device (600a),
When the first alarm device (600e) receives the periodic signal in the downstream communication timeslot allocated to the third alarm device (600a), it transmits the response signal to the third alarm device (600a) in the upstream communication timeslot allocated to the first alarm device (600e),
If the first alarm device (600e) does not receive a retransmission of the periodic signal from the relay device (700) after transmitting the response signal to the third alarm device (600a), it switches from receiving the periodic signal in the downstream communication timeslot allocated to the second alarm device (600c) to receiving the periodic signal in the downstream communication timeslot allocated to the third alarm device (600a) (the alarm system (1000) described in Item 2-1).

(Item 2-3)
A plurality of downstream communication time slots to be assigned to each of the plurality of alarm devices (600) are arranged on a time axis in order to transmit a signal from the relay device (700);
A plurality of upstream communication time slots to be assigned to each of the plurality of alarm devices (600) for transmitting a signal to the relay device (700) are arranged on a time axis;
The signal from the relay device (700) is a periodic signal that is periodically transmitted from the relay device (700),
the signal to the relay device (700) is a response signal to be transmitted when each of the multiple alarm devices (600) receives the periodic signal,
The second alarm device (600c) transmits the periodic signal to the first alarm device (600e) in the downstream communication time slot allocated to the second alarm device (600c),
After transmitting the periodic signal to the first alarm device (600e), the second alarm device (600c) receives the response signal from the first alarm device (600e) in the upstream communications time slot allocated to the first alarm device (600e), and then transmits the response signal in the upstream communications time slot allocated to the second alarm device (600e);
If, after transmitting the periodic signal to the first alarm device (600e), the second alarm device (600c) does not receive the response signal from the first alarm device (600e) in the upstream communications time slot allocated to the first alarm device (600e), then unless a retransmission of the periodic signal from the relay device (700), it will not transmit the periodic signal to the first alarm device (600e) in the downstream communications time slot allocated to the second alarm device (600c), and will not receive the response signal in the upstream communications time slot allocated to the first alarm device (600e) (the alarm system (1000) described in Item 2-1).

(Item 2-4)
A plurality of downstream communication time slots to be assigned to each of the plurality of alarm devices (600) are arranged on a time axis in order to transmit a signal from the relay device (700);
A plurality of upstream communication time slots to be assigned to each of the plurality of alarm devices (600) for transmitting a signal to the relay device (700) are arranged on a time axis;
The signal from the relay device (700) is a periodic signal that is periodically transmitted from the relay device (700),
the signal to the relay device (700) is a response signal to be transmitted when each of the multiple alarm devices (600) receives the periodic signal,
When the third alarm device (600a) receives the response signal from the first alarm device (600e) in the upstream communications time slot allocated to the first alarm device (600e) in a situation where the response signal has not been received from the first alarm device (600e) in the upstream communications time slot allocated to the first alarm device (600e), it transmits the response signal in the upstream communications time slot allocated to the third alarm device (600a),
If the third alarm device (600a) does not receive a retransmission of the periodic signal from the relay device (700), it transmits the periodic signal to the first alarm device (600e) in the downlink communication time slot allocated to the third alarm device (600a) (the alarm system (1000) described in Item 2-1).

(Item 2-5)
The smaller the number of hops to the relay device (700), the earlier the downstream communication time slot is allocated to the alarm device (600),
The greater the number of hops to the relay device (700), the earlier the upstream communication time slot is allocated to the alarm device (600),
When the relay device (700) receives the route switching notification, and the allocation of the alarm device (600) to the downlink communication time slot and the uplink communication time slot is changed, it transmits slot information indicating the changed allocation to each of the multiple alarm devices (600) (an alarm system (1000) described in any one of items 2-2) to (2-4).

(Item 2-6)
The alarm system described in (Item 2-1) above, wherein when the relay device receives the route switching notification, it transmits route information indicating the switched relay route to each of the multiple alarm devices.

(Item 2-7)
An alarm device (600) out of a plurality of alarm devices (600) constituting a multi-hop network spreading out from a relay device (700),
When this alarm device (600) is referred to as the first alarm device (600e), the multiple alarm devices also include a second alarm device (600c) and a third alarm device (600a),
a communication section (620) that receives a signal from the relay device (700) via the second alarm device (600c);
A control unit (624) that controls the communication unit (620),
When reception of a signal from the relay device (700) via the second alarm device (600c) has failed, the communication unit (620) receives a signal from the relay device (700) via the third alarm device (600a),
when the relay route including the second alarm device (600c) is switched to a relay route including the third alarm device (600a), the communication unit (620) transmits a route switching notification to the third alarm device (600a) to notify the relay device (700) of the relay route switching.
Alarm (600).

(Item 2-8)
A communication method in an alarm device (600) out of a plurality of alarm devices (600) that make up a multi-hop network spreading out from a relay device (700), comprising:
When this alarm device (600) is referred to as the first alarm device (600e), the multiple alarm devices (600) also include a second alarm device (600c) and a third alarm device (600a),
receiving a signal from the relay device (700) via the second alarm device (600c);
receiving a signal from the relay device (700) via the third alarm device (600a) when reception of a signal from the relay device (700) via the second alarm device (600c) has failed;
when the relay route including the second alarm device (600c) is switched to a relay route including the third alarm device (600a), transmitting a route switching notification to the third alarm device (600a) to notify the relay device (700) of the relay route switching;
A communication method comprising:

(Item 2-9)
A program to be executed by an alarm device (600) out of a plurality of alarm devices (600) constituting a multi-hop network extending from a relay device (700),
When this alarm device (600) is referred to as the first alarm device (600e), the multiple alarm devices (600) also include a second alarm device (600c) and a third alarm device (600a),
receiving a signal from the relay device (700) via the second alarm device (600c);
receiving a signal from the relay device (700) via the third alarm device (600a) when reception of a signal from the relay device (700) via the second alarm device (600c) has failed;
and a step of sending a route switching notification to the third alarm device (600a) to inform the relay device (700) of the switch of the relay route, when a relay route including the second alarm device (600c) is switched to a relay route including the third alarm device (600a).

The present disclosure has been described above based on examples. These examples are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of each of the components or each of the processing processes, and that such modifications are also within the scope of the present disclosure.

In this embodiment, the relay device 700 connects to a fire alarm 600 that has both a fire detection function and an alarm sounding function. However, this is not limited to the above, and for example, the fire alarm 600 may only have a fire detection function. Furthermore, instead of the fire alarm 600, a sensor that is not limited to fires and detects flood damage, earthquakes, gas leaks, and the generation of CO (carbon monoxide) due to incomplete combustion may also be used. This modified example allows for greater freedom in configuration.

In this embodiment, when a route switching notification is transmitted from the fire alarm device 600 to the relay device 700 and the relay route is updated in the relay device 700, when the allocation of the communication time slot is changed, the relay device 700 transmits slot information to the multiple fire alarm devices 600. However, this is not limited to the above, and for example, the relay device 700 may transmit to each fire alarm device 600 not only slot information but also route information indicating the updated (switched) relay route. Each fire alarm device 600 recognizes the updated relay route based on the received route information. For example, if the number of hops of each fire alarm device 600 does not change even if the relay route is updated, the above-mentioned aging is executed. On the other hand, if the number of hops of each fire alarm device 600 changes when the relay route is updated, route information is transmitted. According to the modified example, the relay route can be switched reliably.

600 Fire alarm (alarm), 620 Communication unit, 622 Processing unit, 624 Control unit, 626 Monitoring unit, 630 Fire detection sensor, 632 Buzzer, 700 Relay device, 710 Communication unit, 712 Output unit, 720 Control unit, 722 Allocation unit, 800 Management device, 1000 Alarm system, 1010 Superframe, 1020 Frame, 1030 Time slot.

Claims (9)

Equipped with multiple alarm devices that form a multi-hop network extending from a relay device,
the plurality of alarm devices include a first alarm device, a second alarm device, and a third alarm device,
the first alarm device receives a signal from the relay device via the second alarm device,
When the first alarm device fails to receive a signal from the relay device via the second alarm device, it receives a signal from the relay device via the third alarm device,
When the first alarm device switches a relay route including the second alarm device to a relay route including the third alarm device, the first alarm device transmits a route switching notification to the third alarm device to notify the relay device of the relay route switching.
Alarm system. a plurality of downstream communication time slots to be allocated to each of the plurality of alarm devices are arranged on a time axis in order to transmit signals from the relay device;
a plurality of upstream communication time slots to be allocated to each of the plurality of alarm devices for transmitting signals to the relay device are arranged on a time axis;
the signal from the relay device is a periodic signal periodically transmitted from the relay device,
the signal to the relay device is a response signal to be transmitted when each of the multiple alarm devices receives the periodic signal,
When the first alarm device receives the periodic signal in the downstream communication timeslot allocated to the second alarm device, it transmits the response signal to the second alarm device in the upstream communication timeslot allocated to the first alarm device,
when the first alarm device fails to receive the periodic signal in the downstream communication timeslot allocated to the second alarm device, it receives the periodic signal in the downstream communication timeslot allocated to the third alarm device,
When the first alarm device receives the periodic signal in the downstream communication timeslot allocated to the third alarm device, it transmits the response signal to the third alarm device in the upstream communication timeslot allocated to the first alarm device,
The alarm system according to claim 1, wherein, if the first alarm device does not receive a retransmission of the periodic signal from the relay device after transmitting the response signal to the third alarm device, it switches from receiving the periodic signal in the downstream communications time slot allocated to the second alarm device to receiving the periodic signal in the downstream communications time slot allocated to the third alarm device. a plurality of downstream communication time slots to be allocated to each of the plurality of alarm devices are arranged on a time axis in order to transmit signals from the relay device;
a plurality of upstream communication time slots to be allocated to each of the plurality of alarm devices for transmitting signals to the relay device are arranged on a time axis;
the signal from the relay device is a periodic signal periodically transmitted from the relay device,
the signal to the relay device is a response signal to be transmitted when each of the multiple alarm devices receives the periodic signal,
the second alarm device transmits the periodic signal to the first alarm device in the downstream communication timeslot allocated to the second alarm device,
After transmitting the periodic signal to the first alarm device, when the second alarm device receives the response signal from the first alarm device in the upstream communications timeslot allocated to the first alarm device, it transmits the response signal in the upstream communications timeslot allocated to the second alarm device,
The alarm system according to claim 1, wherein, after transmitting the periodic signal to the first alarm device, if the second alarm device does not receive the response signal from the first alarm device in the upstream communications time slot allocated to the first alarm device, then, unless it receives a retransmission of the periodic signal from the relay device, it will not transmit the periodic signal to the first alarm device in the downstream communications time slot allocated to the second alarm device, and will not receive the response signal in the upstream communications time slot allocated to the first alarm device. a plurality of downstream communication time slots to be allocated to each of the plurality of alarm devices are arranged on a time axis in order to transmit signals from the relay device;
a plurality of upstream communication time slots to be allocated to each of the plurality of alarm devices for transmitting signals to the relay device are arranged on a time axis;
the signal from the relay device is a periodic signal periodically transmitted from the relay device,
the signal to the relay device is a response signal to be transmitted when each of the multiple alarm devices receives the periodic signal,
when the third alarm device receives the response signal from the first alarm device in the upstream communications timeslot assigned to the first alarm device in a situation where the response signal has not been received from the first alarm device in the upstream communications timeslot assigned to the first alarm device, it transmits the response signal in the upstream communications timeslot assigned to the third alarm device,
The alarm system according to claim 1, wherein, if the third alarm device does not receive a retransmission of the periodic signal from the relay device, it transmits the periodic signal to the first alarm device in the downstream communication timeslot allocated to the third alarm device. The earlier the alarm device is allocated the downstream communication time slot, the smaller the number of hops to the relay device.
The greater the number of hops to the relay device, the earlier the upstream communication time slot is allocated to the alarm device,
5. An alarm system as claimed in any one of claims 2 to 4, wherein when the relay device receives the route switching notification and the allocation of alarm devices to the downlink communication time slots and the uplink communication time slots is changed, the relay device transmits slot information indicating the changed allocation to each of the multiple alarm devices. The alarm system according to claim 1, wherein when the relay device receives the route switching notification, the relay device transmits route information indicating the switched relay route to each of the plurality of alarm devices. An alarm device among multiple alarm devices that make up a multi-hop network spreading out from a relay device,
When this alarm device is referred to as a first alarm device, the multiple alarm devices also include a second alarm device and a third alarm device,
a communication section that receives a signal from the relay device via the second alarm device;
A control unit that controls the communication unit,
When reception of a signal from the relay device via the second alarm device fails, the communication unit receives a signal from the relay device via the third alarm device,
When the relay route including the second alarm device is switched to a relay route including the third alarm device, the communication unit transmits a route switching notification to the third alarm device to notify the relay device of the relay route switching.
Alarm. A communications method for an alarm device among multiple alarm devices that make up a multi-hop network spreading out from a relay device, comprising:
When this alarm device is referred to as a first alarm device, the multiple alarm devices also include a second alarm device and a third alarm device,
receiving a signal from the relay device via the second alarm device;
receiving a signal from the relay device via the third alarm device when reception of a signal from the relay device via the second alarm device has failed;
when the relay route including the second alarm device is switched to a relay route including the third alarm device, sending a route switching notification to the third alarm device to notify the relay device of the relay route switching;
A communication method comprising: A program to be executed by an alarm device among a plurality of alarm devices that make up a multi-hop network extending from a relay device,
When this alarm device is referred to as a first alarm device, the multiple alarm devices also include a second alarm device and a third alarm device,
receiving a signal from the relay device via the second alarm device;
receiving a signal from the relay device via the third alarm device when reception of a signal from the relay device via the second alarm device has failed;
and a step of, when a relay route including the second alarm device is switched to a relay route including the third alarm device, sending a route switching notification to the third alarm device to notify the relay device of the relay route switch.

Images