Alarm system, alarm device, communication method, and program

Abstract

To provide a technique capable of switching a relay route smoothly in a multi-hop network.SOLUTION: A fifth fire alarm device 600e receives a signal from a relay device 700 via a third fire alarm device 600c. The fifth fire alarm device 600e is configured so as to, when reception of a signal from the relay device 700 via the third fire alarm device 600c has failed, receive the signal from the relay device 700 via a first fire alarm device 600a. The fifth fire alarm device 600e is also configured so as to, when having switched the relay route that includes the third fire alarm device 600c to the relay route that includes the first fire alarm device 600a, transmit a route switching notification to notify the relay route switching to the relay device 700 to the first fire alarm device 600a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to alarm technology, and more particularly to an alarm system, an alarm device, a communication method, and a program that use a multi-hop network. [Background technology]

[0002] A smart meter is installed in each house, and a base station collects data by transmitting data between the smart meters using a wireless communication multi-hop method. In the wireless communication multi-hop method, there is a risk that a communication abnormality may occur between nodes, making it impossible to send a communication message from the collection node to the destination sensor node. In that case, a node outside the relay route that detects the abnormality autonomously constructs an alternative route to continue communication (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-50746 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a communication failure occurs in a multi-hop network, retransmission is performed. If the communication failure continues even after retransmission, it is necessary to switch the relay route. It is required to switch the relay route smoothly.

[0005] The present disclosure has been made in consideration of these circumstances, and has an object to provide a technique for smoothly switching relay routes in a multi-hop network. [Means for solving the problem]

[0006] In order to solve the above problems, an alarm system according to an embodiment of the present disclosure comprises multiple alarm devices that form a multi-hop network spreading out 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 relay route switch.

[0007] 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 out 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 sends a route switching notification to the third alarm device to notify the relay device of the relay route switch.

[0008] Yet another aspect of the present disclosure is a communications method. This method is a communications method for an alarm device among multiple alarm devices that make up a multi-hop network spreading from a relay device, where if 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 fails, 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.

[0009] Any combination of the above components, and conversion of the present disclosure into a method, device, system, recording medium, computer program, etc. are also valid aspects of the present disclosure. Effect of the Invention

[0010] According to the present disclosure, relay routes can be smoothly switched in a multi-hop network. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing a configuration of an alarm system according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a diagram showing the configuration of the fire alarm device of FIG. [Diagram 3] 3(a)-(e) are diagrams showing the structure of a superframe used in the alarm system of FIG. [Figure 4] FIG. 2 is a diagram illustrating a configuration of a relay device in FIG. [Diagram 5] FIG. 2 is a diagram showing an overview of communications in the alarm system of FIG. [Figure 6] 6(a)-(b) are diagrams showing formats of the periodic signal and the response signal used in the alarm system of FIG. [Figure 7] 7(a)-(b) show another overview of communications in the alarm system of FIG. [Figure 8] FIG. 2 is a diagram showing an overview of routing in the alarm system of FIG. 1; [Figure 9] FIG. 2 is a sequence diagram showing a routing procedure in the alarm system of FIG. [Figure 10] 10(a)-(b) are diagrams showing a situation when a communication failure occurs in the alarm system of FIG. [Figure 11] 11(a)-(b) are diagrams showing an overview of retransmission in the alarm system of FIG. [Figure 12] 12(a)-(b) show another overview of retransmission in the alarm system of FIG. [Figure 13] 13(a)-(b) are diagrams showing an overview of notifications in the alarm system of FIG. [Figure 14] 14(a)-(b) are diagrams showing an overview of slot switching and aging in the alarm system of FIG. [Figure 15] 15(a) and 15(b) are diagrams showing an overview of communication after route switching in the alarm system of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Before specifically describing the present disclosure, an overview will be provided. This embodiment relates to an alarm system installed in facilities such as an apartment building, a detached house, an office, and a hospital. In the alarm system, a relay device is connected to a management device, and a plurality of 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 the occurrence of 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 performs the instruction to sound when it receives the instruction to sound.

[0013] Here, when a line for a signal from a relay device to a fire alarm device with the greatest number of hops from the relay device is called a "downlink," a line for a signal from the fire alarm device with the greatest number of hops to the relay device is called an "uplink." In this embodiment, one frame is formed by arranging a plurality of time slots, and one superframe is formed by arranging a plurality of frames. Also, one fire alarm device is assigned to one time slot for a downlink (hereinafter referred to as a "downlink communication time slot") and one time slot for an uplink (hereinafter referred to as an "uplink communication time slot"). The downlink communication time slot is used for transfer of the downlink, and the uplink communication time slot is used for transfer of the uplink.

[0014] In the downlink, in addition to instructions to sound, a signal (hereinafter referred to as a "periodic signal") is periodically transmitted from the relay device 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 uplink, 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."

[0015] A fire alarm in a multi-hop network must monitor whether detection results are being transmitted in upstream communication time slots assigned to other downstream fire alarms. In particular, as the number of downstream fire alarms increases, the number of upstream communication time slots that must be monitored increases, resulting in increased power consumption by the fire alarms.

[0016] A monitoring time slot is introduced to suppress an increase in the power consumption of the fire alarm. As described above, the frame includes a plurality of downstream communication time slots and a plurality of 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 an 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, the fire alarm waits to receive a communication signal in the upstream communication time slot assigned to it. On the other hand, if a fire alarm does not receive a monitoring signal in the monitoring time slot, the fire alarm does not wait to receive a communication signal in the upstream communication time slot assigned to it.

[0017] 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 does not always reach the fire alarm. Such communication environments include, for example, the presence of a fixed obstruction (iron door) due to a layout change, and interference from stationary jamming waves. Under such circumstances, it is required to smoothly switch relay routes in a multi-hop network.

[0018] 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 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".

[0019] 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 wall.

[0020] Here, the first fire alarm 600a to the sixth fire alarm 600f constitute a multi-hop network spreading from the relay device 700. For example, a relay route connecting the relay device 700 and the first fire alarm 600a, and a relay route connecting the relay device 700, the second fire alarm 600b, the third fire alarm 600c, and the fourth fire alarm 600d are formed. In addition, a relay route connecting the relay device 700, the second fire alarm 600b, the third fire alarm 600c, the fifth fire alarm 600e, and the sixth fire alarm 600f is also formed. Such relay routes are determined in each fire alarm 600 and are also shared by the relay device 700 and the management device 800.

[0021] In these relay routes, the first fire alarm 600a and the second fire alarm 600b can communicate with the relay device 700 with a hop number of "1", and the third fire alarm 600c can communicate with the relay device 700 with a hop number of "2". The fourth fire alarm 600d and the fifth fire alarm 600e can communicate with the relay device 700 with a hop number of "3", and the sixth fire alarm 600f can communicate with the relay device 700 with a hop number of "4". Focusing on the fifth fire alarm 600e, the fifth fire alarm 600e receives a signal from the relay device 700 via the third fire alarm 600c, but can also receive a signal from the relay device 700 via the first fire alarm 600a or the fourth fire alarm 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.

[0022] 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. It can also be said that the relay device 700 relays 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 perform wireless communication.

[0023] The management device 800 is, for example, a controller of a Home Energy Management System (HEMS) installed in a facility. The management device 800 is capable of communicating with a plurality of devices installed in the facility. The plurality of devices include, for example, air conditioners, lighting devices, water heaters, and the like, each having a communication function. The management device 800 is also capable of communicating with a relay device 700 installed in the facility. Furthermore, the management device 800 is also capable of communicating with each fire alarm 600 via the relay device 700.

[0024] FIG. 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.

[0025] The communication unit 620 performs wireless communication with other fire alarms 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 the fire detection sensor 630, that is, may have both a detection function and a communication function. Such a fire alarm 600 can also be said to be a sensor capable of issuing an alarm when a fire is detected.

[0026] 3(a)-(e) show the configuration of a superframe 1010 used in the alarm system 1000. As shown in FIG. 3(a), a certain period is defined as a superframe 1010. The superframe 1010 is arranged repeatedly. The superframe 1010 is divided into a plurality of frames 1020. As shown in FIG. 3(b), one frame 1020 is divided into a plurality of time slots 1030. Of the plurality of time slots 1030, one or more time slots 1030 at the beginning are used as "downstream communication time slots". The plurality of downstream communication time slots are time slots 1030 to be assigned to each of the plurality of fire alarm devices 600 in order to transmit a signal from the relay device 700, and are arranged on the time axis.

[0027] 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.

[0028] Fig. 3(c) shows a timeslot 1030 to be used as a timeslot for downstream communication or an timeslot for upstream communication. The length of this timeslot 1030 is set to "A". Fig. 3(d) shows a timeslot 1030 to be used as a monitoring timeslot. The length of this timeslot 1030 is set to "B". "B" is set to a value smaller than "A".

[0029] Fig. 3(e) shows an example of using multiple frames 1020 in a superframe 1010. "Regular monitoring" is performed in the first frame 1020 of the superframe 1010. "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 the "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".

[0030] 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 in the "regular monitoring" and "same route retransmission".

[0031] 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 the fire alarms 600 is confirmed in the periodic monitoring, same route retransmission, and different route retransmission, the remaining frames 1020 of the same route retransmission or different route retransmission are used for "detection waiting". Since the periodic monitoring, same route retransmission, and different route retransmission are performed at predetermined timing, the fire alarm 600 and the relay device 700 recognize the timing of the periodic monitoring, same route retransmission, and different route retransmission. Also, in the frames 1020 of "periodic monitoring", "same route retransmission", and "same route retransmission", when the fire alarm 600 detects the occurrence of a fire, the detection result is transmitted from the fire alarm 600.

[0032] 4 shows the configuration of a relay device 700. The relay device 700 can be said to be a control device for a plurality of fire alarms 600 that form a multi-hop network. The relay device 700 includes a communication unit 710 and a control unit 720, 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 plurality of relay devices 700, and also has a communication function for communicating with a management device 800. The control unit 720 controls the operation of the relay device 700.

[0033] The communication unit 710 communicates with the multiple fire alarm devices 600 that make up the multi-hop network, and receives the results of routing performed in each fire alarm device 600. The routing performed in each fire alarm device 600 will be described later, but each relay route as shown in FIG. 1 is formed based on the routing results.

[0034] 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 device 600. The output unit 712 outputs the allocation result from the allocation unit 722 as slot information to the multiple fire alarm devices 600. 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 device 600.

[0035] Fig. 5 shows an overview of communications in the alarm system 1000, in particular an overview of "regular monitoring." Here, it is assumed that the relay routes in the alarm system 1000 are formed as shown in Fig. 1. In Fig. 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."

[0036] 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 are assigned to the downstream communication time slot 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 alarm 600 with the smaller number of hops to the relay device 700 is assigned to the front of the downstream communication time slot.

[0037] The upstream communication time slots are allocated in order from the front to the sixth fire alarm 600f, fifth fire alarm 600e, fourth fire alarm 600d, third fire alarm 600c, second fire alarm 600b, first fire alarm 600a, and relay device 700. In other words, the fire alarm 600 with the greater number of hops to the relay device 700 is allocated closer to the front in the upstream communication time slots.

[0038] When focusing on the fifth fire alarm 600e, in the downstream communication time slot, the fifth fire alarm 600e is assigned to the rear of the fourth fire alarm 600d and in front of the sixth fire alarm 600f. In the upstream communication time slot, the fifth fire alarm 600e is assigned to the rear of the sixth fire alarm 600f and in front of the fourth fire alarm 600d.

[0039] 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".

[0040] 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.

[0041] The allocation of these time slots 1030 is decided by the relay device 700 or the management device 800. For example, the relay device 700 or the management device 800 decides 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 decided 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 slot 1030 in which it should transmit a communication signal and which has been allocated to itself. The fire alarm device 600 also knows the time slot 1030 in which it can receive a communication signal from an adjacent fire alarm device 600 or relay device 700 on the relay route.

[0042] 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). Furthermore, 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.

[0043] 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 described above, a 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.

[0044] FIG. 6(b) shows the format of the response signal, that is, the signal to be transmitted 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 upper-level fire alarm device 600 or relay device 700 to which the next signal should be transmitted 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 FIG. 5.

[0045] The triangle marks in Fig. 5 indicate intermittent reception operation performed by the communication unit 620 of the fire alarm 600. In the intermittent reception operation in the communication unit 620, the reception operation is 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, the reception operation is stopped for the remaining period 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 is continued for the remaining period of the time slot 1030. The intermittent reception operation is performed to reduce power consumption.

[0046] In downstream communication, the fire alarm device 600 performs intermittent reception only in the time slots 1030 assigned to other upper-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.

[0047] The relay device 700 transmits a periodic signal in the time slot 1030 "M" of 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 the time slot 1030 "M". The second fire alarm device 600b transmits a periodic 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 and the fifth fire alarm device 600e receive 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".

[0048] The sixth fire alarm device 600f transmits a response signal in the time slot 1030 "C6" of the upstream communication time slot. The fifth fire alarm device 600e receives the response signal in the 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 the time slot 1030 "C5". The third fire alarm device 600c receives the response signal in the time slot 1030 "C5".

[0049] The fourth fire alarm device 600d transmits a response signal in the time slot 1030 "C4". The third fire alarm device 600c receives the response signal in the 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 the time slot 1030 "C3".

[0050] The second fire alarm device 600b receives the response signal in the time slot 1030 "C3". The second fire alarm device 600b generates a response signal by concatenating its own response with the response signal from the third fire alarm device 600c, and transmits the 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".

[0051] 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.

[0052] 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 the 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.

[0053] The fifth fire alarm device 600e receives a 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 periodic 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.

[0054] After transmitting a periodic signal to the fifth fire alarm 600e, the third fire alarm 600c receives a response signal from the fifth fire alarm 600e by intermittent reception in the upstream communication time slot assigned to the fifth fire alarm 600e. The third fire alarm 600c transmits a response signal in the upstream communication time slot assigned to the third fire alarm 600c.

[0055] Here, if the fifth fire alarm 600e is referred to as the first alarm, the third fire alarm 600c is referred to as the second alarm, the first fire alarm 600a is referred to as the third alarm, and the fourth fire alarm 600d is referred to as the fourth alarm.

[0056] 7(a)-(b) show another overview of communication in the alarm system 1000, particularly an overview of "waiting for detection." In FIG. 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."

[0057] The fifth fire alarm device 600e transmits a monitoring signal in the monitoring timeslot of the timeslot 1030 "N2". The third fire alarm device 600c receives a monitoring signal in the monitoring timeslot of the timeslot 1030 "N2". The third fire alarm device 600c transmits a monitoring signal in the monitoring timeslot of the timeslot 1030 "N1". The second fire alarm device 600b receives a monitoring signal in the monitoring timeslot of the timeslot 1030 "N1".

[0058] As a result, the monitoring signal is transferred from the sixth fire alarm device 600f, which is at the lowest side of the multi-hop network, to the second fire alarm device 600b, which has a hop count of "1", within one frame 1020. On the other hand, if the fire detection sensors 630 of all the fire alarm devices 600 do not detect the occurrence of a fire, the monitoring signal is not transferred.

[0059] The sixth fire alarm 600f transmits the detection result in the time slot 1030 "C6" of the upstream communication time slot. The fifth fire alarm 600e receives the detection result in the time slot 1030 "C6". Here, the monitoring unit 626 of the fifth fire alarm 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 600e performs intermittent reception in the time slot 1030 "C6". On the other hand, if the monitoring unit 626 of the fifth fire alarm 600e does not detect the reception of a monitoring signal, the fifth fire alarm 600e stops the reception process of the communication signal in the time slot 1030 "C6".

[0060] The fifth fire alarm device 600e transfers the detection result in the time slot 1030 "C5". The third fire alarm device 600c receives the detection result in the time slot 1030 "C5". The third fire alarm device 600c transfers the detection result in the time slot 1030 "C3". The second fire alarm device 600b receives the detection result in the time slot 1030 "C3". The second fire alarm device 600b transfers the detection result in the time slot 1030 "C2". The relay device 700 receives the detection result in the time slot 1030 "C2".

[0061] When the relay device 700 receives the detection result from the second fire alarm 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 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 600 to be activated is stored in advance in the management device 800. Here, for example, the fifth fire alarm 600e and the sixth fire alarm 600f are identified. The management device 800 transmits an instruction to activate the alarm to the relay device 700, with the identified fire alarm 600 as the final destination.

[0062] 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 the relay device 700, the second fire alarm 600b, the third fire alarm 600c, the fifth fire alarm 600e, and the sixth fire alarm 600f. When the communication units 620 of the fifth fire alarm 600e and the 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 blink.

[0063] (2) Routing Up to this point, it has been 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).

[0064] 9 is a sequence diagram showing the routing procedure in the alarm system 1000. Here, the routing process will be explained with a focus on the (n+3)th fire alarm 600n+3. Each fire alarm 600 broadcasts a HELLO message at regular time intervals. The HELLO message includes route quality information from the fire alarm 600 to the relay device 700. The communication unit 620 of the (n+3)th fire alarm 600n+3 receives HELLO messages from the (n+1)th fire alarm 600n+1, the (n+2)th fire alarm 600n+2, and the (n+4)th fire alarm 600n+4 (S10, S12, S14).

[0065] The communication unit 620 of the (n+3)th 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 changes according to the received power, and is a value that decreases as the received power increases. The above-mentioned route quality is also indicated in the same way as the link quality. The control unit 624 derives the tentative route cost as follows by adding the link quality of the (n+1)th fire alarm device 600n+1 and the route quality included in the HELLO message from the (n+1)th fire alarm device 600n+1: 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.

[0066] 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 ascending order of tentative route cost as priority link destinations. Here, for example, the (n+1)th fire alarm 600n+1 and the (n+2)th fire alarm 600n+2 are selected as priority link destinations.

[0067] 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 a HELLO message (S16, S18). The (n+1)th fire alarm 600n+1 and the (n+2)th fire alarm 600n+2 transmit the link quality in the opposite direction in a LINK_REP sub-message (S20, S22).

[0068] 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 adds the selected link quality and the route quality for the (n+1)th fire alarm device 600n+1 to derive a formal route cost as follows: Formal route cost = route quality + Ka × Max (link quality) + Kb × C Equation (2) Here, Max denotes selecting the maximum link quality.

[0069] The control unit 624 also derives an official route cost for the (n+2)th fire alarm 600n+2. The control unit 624 compares the official route cost for the (n+1)th fire alarm 600n+1 with the official route cost for the (n+2)th 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.

[0070] That is, the n+3 fire alarm 600n+3 derives a formal route cost (hereinafter referred to as a "first cost") for a relay route (hereinafter referred to as a "first relay route") for communicating with the relay device 700 via the n+1 fire alarm 600n+1 by exchanging link quality information with the n+1 fire alarm 600n+1. Also, the n+3 fire alarm 600n+3 derives a formal route cost (hereinafter referred to as a "second relay route") for communicating with the relay device 700 via the n+2 fire alarm 600n+2 by exchanging link quality information with the n+2 fire alarm 600n+2. Furthermore, the n+3 fire alarm 600n+3 preferentially selects the relay route that is smaller than the first cost or the second cost. A relay route is formed by performing such processing in each fire alarm 600. Information about the relay route (alternative route) formed in each fire alarm device 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).

[0071] (3) Occurrence of communication failure Figures 10(a)-(b) show a situation when 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.

[0072] FIG. 10(b) shows an overview of communication in the situation of FIG. 10(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 the regular signal in the time slot 1030 "M." The second fire alarm device 600b transmits a regular signal in the time slot 1030 "C2." The third fire alarm device 600c receives a regular signal in the time slot 1030 "C2." The third fire alarm device 600c transmits a regular signal in the time slot 1030 "C3." The fourth fire alarm device 600d and the fifth fire alarm device 600e perform intermittent reception in the 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 device 600f either.

[0073] 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".

[0074] The second fire alarm device 600b receives the response signal in the time slot 1030 "C3". The second fire alarm device 600b generates a response signal by concatenating its own response with the response signal from the third fire alarm device 600c, and transmits the 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".

[0075] 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, the "detection waiting" is executed from the next frame 1020.

[0076] (4) Retransmission via 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.

[0077] FIG. 11(a)-(b) shows an overview of retransmission in the alarm system 1000. FIG. 11(a) shows a situation following FIG. 10(a). Up until now, the fifth fire alarm 600e has used a relay route via the third fire alarm 600c as a relay route toward the relay device 700. However, in the situation of FIG. 10(a), the fifth fire alarm 600e fails to receive a periodic signal from the relay device 700 via the third fire alarm 600c. In a frame 1020 shown as another route retransmission in FIG. 3(e), the control unit 624 of the fifth fire alarm 600e causes the communication unit 620 to perform intermittent reception in all time slots 1030 (except the time slot 1030 assigned to the fifth fire alarm 600e) in the downstream communication time slot. As a result, the communication unit 620 receives the periodic signal from the first fire alarm 600a and the periodic signal from the fourth fire alarm 600d. The control unit 624 transmits a regular signal to the sixth fire alarm device 600f in the time slot 1030 assigned to the fifth fire alarm device 600e.

[0078] 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 the 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.

[0079] FIG. 11(b) shows an overview of communication in the situation of FIG. 11(a), particularly an overview of "another route retransmission." The relay device 700 transmits a periodic signal in the time slot 1030 "M" of the downstream communication time slot. The first fire alarm device 600a and the second fire alarm device 600b receive the periodic signal in the time slot 1030 "M." The first fire alarm device 600a transmits a periodic signal in the time slot 1030 "C1." The fifth fire alarm device 600e receives a periodic signal in the time slot 1030 "C1." The second fire alarm device 600b transmits a periodic 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."

[0080] The fourth fire alarm 600d and the fifth fire alarm 600e perform intermittent reception in the time slot 1030 "C3". The fourth fire alarm 600d receives the periodic signal, but the fifth fire alarm 600e fails to receive the periodic signal. The fourth fire alarm 600d transmits a periodic signal in the time slot 1030 "C4". The fifth fire alarm 600e receives the periodic signal in the time slot 1030 "C4".

[0081] 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 the 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 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".

[0082] The sixth fire alarm 600f transmits a monitoring signal in the monitoring timeslot of the timeslot 1030 "N3". The fifth fire alarm 600e receives a monitoring signal in the monitoring timeslot of the timeslot 1030 "N3". The fourth fire alarm 600d transmits a monitoring signal in the monitoring timeslot of the timeslot 1030 "N2". The third fire alarm 600c receives a monitoring signal in the monitoring timeslot of the timeslot 1030 "N2".

[0083] 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".

[0084] 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 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 a response signal in time slot 1030 "C5".

[0085] The fourth fire alarm device 600d transmits a response signal in the time slot 1030 "C4" of the upstream communication time slot. The third fire alarm device 600c receives the response signal in the time slot 1030 "C4". The third fire alarm device 600c transmits a response signal in the time slot 1030 "C3". The second fire alarm device 600b receives the 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".

[0086] 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 such processing, the route information stored in the relay device 700 and each fire alarm device 600, that is, the routing information, corresponds to the relay route in FIG. 1 (hereinafter referred to as the "main route"), but the notification signal and the response signal are transmitted along the alternative route by using the monitoring signal. In other words, when the notification signal is transmitted along the alternative route, the 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.

[0087] (5) Retransmission via a new route (part 2) FIG. 12(a)-(b) shows 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 600e has used a relay route via the third fire alarm 600c as a relay route toward the relay device 700. However, in the situation of FIG. 10(a), the fifth fire alarm 600e fails to receive a regular signal from the relay device 700 via the third fire alarm 600c. Meanwhile, the control unit 624 of the fifth fire alarm 600e derives link quality to other surrounding fire alarms 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 600a, the third fire alarm 600c, and the fourth fire alarm 600d is derived.

[0088] In the frame 1020 indicated as "another route retransmission" in FIG. 3(e), the control unit 624 of the fifth fire alarm 600e compares the link quality with each fire alarm 600, and selects the other fire alarm 600 with the lowest link quality, excluding the third fire alarm 600c. This corresponds to selecting the other fire alarm 600 with the highest communication quality, excluding the third fire alarm 600c. Here, the first fire alarm 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 600a in the downstream communication time slot. As a result, the communication unit 620 receives a periodic signal from the first fire alarm 600a. That is, 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.

[0089] 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 first fire alarm device 600a to the relay device 700. 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.

[0090] Fig. 12(b) shows an overview of communication in the situation of Fig. 12(a), particularly an overview of "another route retransmission". The fifth fire alarm device 600e in Fig. 11(b) performs intermittent reception in the time slots 1030 "C1" to "C4" and "C6" in the downstream communication time slot. On the other hand, the fifth fire alarm device 600e in Fig. 12(b) performs intermittent reception in the time slot 1030 "C1" in the downstream communication time slot, but does not perform intermittent reception in the time slots 1030 "C2" to "C4" and "C6". Other than that, it is the same as Fig. 11(b), so a description will be omitted here.

[0091] (6) Route change notification By the process of (4) Retransmission along a new route (part 1) or (5) Retransmission along a new route (part 2), communication along an alternative route becomes possible even if communication along the original route fails. Following this, in the alarm system 1000, the alternative route is changed to the original route.

[0092] Fig. 13(a)-(b) show an overview of notifications in the alarm system 1000. Fig. 13(a) shows a situation following Fig. 11(a) or Fig. 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 switching of the relay route. 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.

[0093] FIG. 13(b) shows an overview of communications in the situation of FIG. 13(a). The fifth fire alarm device 600e, which generated the route switching notification, transmits a monitoring signal in the monitoring time slot of the time slot 1030 "N1". The first fire alarm device 600a receives the monitoring signal in the monitoring time slot of the time slot 1030 "N1". The fifth fire alarm device 600e transmits a route switching notification in the time slot 1030 "C5". The first fire alarm device 600a, which received the route switching notification in the time slot 1030 "C5", transmits a route switching notification in the time slot 1030 "C1". The relay device 700 receives the route switching notification in the time slot 1030 "C1".

[0094] 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 in 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".

[0095] (7) Slot switching and aging When there is a fire alarm 600 whose number of hops to the relay device 700 is changed due to the 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 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 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 alarms 600. The slot information is transmitted, for example, by the downstream communication time slot before the change of the allocation. Each fire alarm 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 600 to the downstream communication time slot and the upstream communication time slot is actually changed.

[0096] Each fire alarm device 600 recognizes the change in the time slot for downstream communication and the time slot for upstream communication, but does not recognize the changed relay route. Therefore, each fire alarm device 600 also performs intermittent reception in the time slots 1030 assigned to other fire alarm devices 600 that were connected in the relay route before the change, but will not be connected in 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 device 600 performs an aging process to forget the relay route before the change and to remember the relay route after the change.

[0097] 14(a)-(b) show an overview of slot switching and aging in the alarm system 1000. FIG. 14(a) shows a situation following FIG. 13(a). Although the allocation of the fire alarm device 600 to the downstream communication time slot and the upstream communication time slot has been changed, the relay route is shown in the same manner as FIG. 13(a). In such a 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.

[0098] The aging process is performed in "regular monitoring". The fifth fire alarm 600e receives a periodic signal in the downstream communication time slot assigned to the first fire alarm 600a. Furthermore, when the fifth fire alarm 600e receives the periodic 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 the response signal to the first fire alarm 600a, if the fifth fire alarm 600e does not receive a retransmission of the periodic 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 the periodic signal in the downstream communication time slot assigned to the third fire alarm 600c to the reception of the periodic signal in the downstream communication time slot assigned to the first fire alarm 600a.

[0099] 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.

[0100] 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 downstream side. This corresponds to transmitting a periodic signal to the fifth fire alarm 600e in the downstream communication time slot assigned to the first fire alarm 600a.

[0101] FIG. 14(b) shows an overview of communication in the situation of FIG. 14(a), particularly an overview of communication during aging processing. Due to a 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.

[0102] 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 a 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".

[0103] The fourth fire alarm 600d and the fifth fire alarm 600e perform intermittent reception in the time slot 1030 "C3". The fourth fire alarm 600d receives the periodic signal, but the fifth fire alarm 600e fails to receive the periodic signal. The fifth fire alarm 600e transmits a periodic signal in the time slot 1030 "C5". The sixth fire alarm 600f receives a periodic signal in the time slot 1030 "C5".

[0104] The fourth fire alarm 600d and the sixth fire alarm 600f transmit a monitoring signal in the monitoring time slot of the time slot 1030 "N2". The third fire alarm 600c and the fifth fire alarm 600e receive a monitoring signal in the monitoring time slot of the time slot 1030 "N2". The third fire alarm 600c and the fifth fire alarm 600e transmit a monitoring signal in the monitoring time slot of the time slot 1030 "N1". The first fire alarm 600a and the second fire alarm 600b receive a monitoring signal in the monitoring time slot of the time slot 1030 "N2".

[0105] The sixth fire alarm device 600f transmits a response signal in the time slot 1030 "C6" of the upstream communication time slot. The fifth fire alarm device 600e receives a response signal in the time slot 1030 "C6". The fourth fire alarm device 600d transmits a response signal in the time slot 1030 "C4" of the upstream communication time slot. The third fire alarm device 600c receives a response signal in the time slot 1030 "C4".

[0106] 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 thereof will be 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 repeater 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 repeater device 700 receives the response signal in the time slot 1030 "C1".

[0107] 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 retransmit the periodic signal. By this process, the aging conditions are satisfied in each fire alarm device 600, and the relay route before the change is erased.

[0108] (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 the 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 the 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 the 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 600c receives a periodic signal in the time slot 1030 "C2". The third fire alarm 600c transmits a periodic signal in the time slot 1030 "C3". The fourth fire alarm 600d receives a periodic signal in the time slot 1030 "C3". The fifth fire alarm 600e transmits a periodic signal in the time slot 1030 "C5". The sixth fire alarm 600f receives a periodic signal in the time slot 1030 "C5".

[0109] The sixth fire alarm device 600f transmits a response signal in the time slot 1030 "C6" of the upstream communication time slot. The fifth fire alarm device 600e receives a response signal in the time slot 1030 "C6". The fourth fire alarm device 600d transmits a response signal in the time slot 1030 "C4" of the upstream communication time slot. The third fire alarm device 600c receives a response signal in the time slot 1030 "C4". The fifth fire alarm device 600e transmits a response signal in the time slot 1030 "C5". The response signals are the same as before, so a description thereof will be omitted here. The first fire alarm device 600a receives a response signal in the time slot 1030 "C5".

[0110] The third fire alarm device 600c transmits a response signal in the time slot 1030 "C3". The second fire alarm device 600b receives the 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". Since the relay route has been switched and regular monitoring is performed at a predetermined timing, the monitoring time slot is not used in upstream communication.

[0111] The subject of the device, system, or method in the present disclosure includes a computer. The computer executes a program to realize the function of the subject of the device, system, or method in the present disclosure. The computer includes a processor that operates according to a program as a main hardware configuration. The type of the processor does not matter 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, an optical disk, or a 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.

[0112] 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 failure. Furthermore, since multiple relay routes are secured, it is possible to smoothly switch relay routes 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, a signal from another fire alarm device 600 is received, so it is possible to smoothly switch relay routes in a multi-hop network.

[0113] In addition, since signals from two or more other unconnected fire alarm devices 600 can be received, communication reliability can be further improved even during constant communication failure. In addition, since signals from two or more other unconnected fire alarm devices 600 can be received, relay route switching can be smoothly performed in a multi-hop network. In addition, since signals from two or more other unconnected fire alarm devices 600 can be received, and 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, relay route switching can be smoothly performed in a multi-hop network. In addition, since signals from two or more other unconnected fire alarm devices 600 can be received, and 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, relay route switching can be efficiently performed. In addition, since an upstream signal is transmitted to a fire alarm device 600 that has received a downstream signal, upstream communication reliability can be improved.

[0114] Furthermore, when the relay route is switched, a route switching notification is transmitted to inform the relay device 700 of the switching 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, since unnecessary reception processing is stopped, an increase in power consumption can be suppressed.

[0115] Furthermore, if, after transmitting a periodic signal to a fire alarm 600, a response signal is not received in the upstream communication time slot assigned to that fire alarm 600, unless a retransmission of the periodic signal from the relay device 700 is received, communication is not performed in the downstream communication time slot and the upstream communication time slot assigned to that fire alarm 600, so that 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 unless a retransmission of the periodic signal from the relay device 700 is received, a periodic signal is transmitted to that fire alarm 600, so that the relay route can be smoothly switched in the multi-hop network.

[0116] Furthermore, the fire alarm 600 with a smaller number of hops to the relay device 700 is assigned a time slot for downstream communication earlier, so that transfer can be completed within the frame 1020. Furthermore, the fire alarm 600 with a larger number of hops to the relay device 700 is assigned a time slot for upstream communication earlier, so that transfer can be completed within the frame 1020. Furthermore, when a route switching notification is received, if the allocation of the fire alarm 600 to the time slots for downstream communication and the time slots for upstream communication is changed, the slot information is transmitted, so that the change in allocation can be notified.

[0117] 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).

[0118] (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) (an alarm system (1000) described in item 1-1).

[0119] (Item 1-3) The plurality of alarm devices (600) also includes a fourth alarm device (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).

[0120] (Items 1-4) The plurality of alarm devices (600) also includes a fourth alarm device (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).

[0121] (Items 1-5) When the first alarm device (600e) is receiving a signal from the relay device (700) via the second alarm device (600c), it transmits a signal intended for the relay device (700) to the second alarm device (600c), The alarm system (1000) described in any one of (item 1-1) to (item 1-3) above, wherein, when a signal from the relay device (700) is received via the third alarm device (600a), the first alarm device (600e) transmits a signal intended for the relay device (700) to the third alarm device (600a).

[0122] (Items 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:

[0123] (Items 1-7) A communications method in an alarm device (600) out of multiple 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:

[0124] (Items 1-8) A program to be executed by an alarm device (600) out of a plurality of alarm devices (600) that make up 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 making it possible to receive a signal from the relay device (700) also via the third alarm device (600a).

[0125] (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), 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), 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).

[0126] (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 signals 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 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), The alarm system (1000) described in (item 2-1) above, wherein 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 communications time slot allocated to the second alarm device (600c) to receiving the periodic signal in the downstream communications time slot allocated to the third alarm device (600a).

[0127] (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 signals 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); The alarm system (1000) described in (Item 2-1) above, in which 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 is received 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) (Item 2-1).

[0128] (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 signals 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), The alarm system (1000) described in (item 2-1) above, wherein 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 downstream communication time slot allocated to the third alarm device (600a).

[0129] (Item 2-5) The smaller the number of hops to the relay device (700) of the alarm device (600), 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).

[0130] (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.

[0131] (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); If reception of a signal from the relay device (700) via the second alarm device (600c) fails, 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).

[0132] (Item 2-8) A communications method in an alarm device (600) out of multiple 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) if 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:

[0133] (Item 2-9) A program to be executed by an alarm device (600) out of a plurality of alarm devices (600) that make up 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) if 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 relay route switch, when the relay route including the second alarm device (600c) is switched to a relay route including the third alarm device (600a).

[0134] The present disclosure has been described above based on the embodiments. These embodiments are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component or each treatment process, and that such modifications are also within the scope of the present disclosure.

[0135] In this embodiment, the relay device 700 is connected to a fire alarm 600 that has both a fire detection function and an alarm sound generation function. However, the present invention is not limited to this, and the fire alarm 600 may have only a fire detection function. Also, instead of the fire alarm 600, a sensor that detects not only fire but also flood damage, earthquakes, gas leaks, and CO (carbon monoxide) generation due to incomplete combustion may be used. According to this modification, the degree of freedom of the configuration can be improved.

[0136] In this embodiment, when a route switching notification is transmitted from the fire alarm 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 600 not only slot information but also route information indicating the updated (switched) relay route. Each fire alarm 600 recognizes the updated relay route based on the received route information. For example, if the number of hops of each fire alarm 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 600 changes when the relay route is updated, route information is transmitted. According to the modified example, the relay route can be switched reliably. [Explanation of symbols]

[0137] 600 fire alarm (alarm), 620 communication section, 622 processing section, 624 control section, 626 monitoring section, 630 fire detection sensor, 632 buzzer, 700 relay device, 710 communication section, 712 output section, 720 control section, 722 allocation section, 800 management device, 1000 alarm system, 1010 superframe, 1020 frame, 1030 time slot.

Claims

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. The alarm system according to claim 1 , 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.

7. 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.

8. 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:

9. 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 when a relay route including the second alarm device is switched to a relay route including the third alarm device, a step of sending a route switching notification to the third alarm device to notify the relay device of the relay route switch.

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