Communication system and wireless communication terminal

Abstract

To provide a communication system and a wireless communication terminal capable of grasping in advance a wireless communication terminal that cannot be detoured.SOLUTION: The communication system 100 includes a plurality of low order wireless communication terminals 22, and a high order wireless communication terminal 21. Each of the plurality of low order wireless communication terminals 22 broadcasts a response requiring signal, receives response information from a bypass destination candidate terminal that is another low order wireless communication terminal 22 within a wireless communication range of its own terminal, and transmits the received response information to the high order wireless communication terminal 21. The high order wireless communication terminal 21 includes a storage unit 212 and a processing unit 211. The storage unit 212 stores the response information received from each of the plurality of low order wireless communication terminals 22. The processing unit 211 identifies the low order wireless communication terminal 22 that cannot execute communication with corresponding detour destination candidate terminals from among the plurality of low order wireless communication terminals 22 on the basis of response information stored in the storage unit 212 and current response information received from each of the plurality of low order wireless communication terminals 22.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a communication system and a wireless communication terminal. [Background technology]

[0002] One type of wireless communication system is a telemetry system (see, for example, Patent Document 1). The telemetry system includes a master unit and multiple slave units. In the wireless telemetry system of Patent Document 1, when a slave unit is unable to communicate with a predetermined communication partner, it selects another slave unit located within its own communication range as a detour destination terminal (relay terminal), forms a detour route between the slave unit and the detour destination terminal, and transmits a message to the detour destination terminal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-207250 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the slave unit may be unable to communicate with the detouring terminal due to some reason (for example, an increase in traffic volume around the slave unit, or a malfunction). In this case, the slave unit cannot make a detouring. In the wireless telemetry system of Patent Document 1, it is not possible to know in advance the wireless communication terminal that cannot be detouring when communication with a predetermined communication partner becomes impossible. Therefore, there is room for improvement in the wireless telemetry system of Patent Document 1.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a communication system and a wireless communication terminal that can identify in advance wireless communication terminals that cannot be bypassed in the event that communication with a predetermined communication partner becomes impossible. [Means for solving the problem]

[0006] The communication system of the present invention includes a plurality of lower wireless communication terminals and an upper wireless communication terminal that communicates with the plurality of lower wireless communication terminals. Each of the plurality of lower wireless communication terminals broadcasts a response request signal, receives response information from other lower wireless communication terminals that are detour destination candidate terminals within a wireless communication range of the terminal, and transmits the received response information to the upper wireless communication terminal. The response information includes information unique to each of the other lower wireless communication terminals. The upper wireless communication terminal includes a storage unit and a processing unit. The storage unit stores the response information received from each of the plurality of lower wireless communication terminals. The processing unit identifies, from among the plurality of lower wireless communication terminals, a first lower wireless communication terminal that has not been able to receive the response information from each other based on the response information stored in the storage unit and the current response information received from each of the plurality of lower wireless communication terminals, and identifies, from among the identified first lower wireless communication terminals, a second lower wireless communication terminal that cannot communicate with the corresponding detour destination candidate terminal.

[0007] The wireless communication terminal of the present invention communicates with a plurality of lower wireless communication terminals. Each of the plurality of lower wireless communication terminals broadcasts a response request signal, receives response information from other lower wireless communication terminals that are detour destination candidate terminals within the wireless communication range of the terminal, and transmits the received response information to the wireless communication terminal. The response information includes information unique to each of the other lower wireless communication terminals. The wireless communication terminal includes a storage unit and a processing unit. The storage unit stores the response information received from each of the plurality of lower wireless communication terminals. The processing unit identifies, from among the plurality of lower wireless communication terminals, a first lower wireless communication terminal that has not been able to receive the response information from each other, based on the response information stored in the storage unit and the current response information received from each of the plurality of lower wireless communication terminals, and identifies, from among the identified first lower wireless communication terminals, a second lower wireless communication terminal that cannot communicate with the corresponding detour destination candidate terminal. Effect of the Invention

[0008] According to the communication system and wireless communication terminal of the present invention, it is possible to know in advance which wireless communication terminal cannot be detoured when communication with a predetermined communication partner becomes impossible. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating a communication system according to a first embodiment of the present invention. [Diagram 2] 1 is a block diagram showing a configuration of a slave unit included in a communication system according to a first embodiment of the present invention. [Diagram 3] 1 is a block diagram showing a configuration of a parent unit according to a first embodiment of the present invention. [Figure 4] 5 is a flowchart showing a process executed by a control unit of the parent device according to the first embodiment of the present invention. [Diagram 5] 6 is a flowchart showing a second determination process, a second notification process, a third determination process, and a third notification process executed by a control unit of the parent device according to the first embodiment of the present invention. [Figure 6] 11 is a sequence diagram showing a beacon collection process executed by a control unit of a master device. FIG. [Figure 7] 11 is a sequence diagram showing a detouring destination candidate search process executed by a control unit of the first child device. FIG. [Figure 8] 11 is a sequence diagram showing a detouring destination candidate search process executed by a control unit of the second handset. FIG. [Figure 9] 11 is a sequence diagram showing a detouring destination candidate search process executed by a control unit of the third handset. FIG. [Figure 10] 13 is another sequence diagram showing the detouring destination candidate search process executed by the control unit of the second handset. FIG. [Figure 11] 13 is another sequence diagram showing the detouring destination candidate search process executed by the control unit of the third handset. FIG. [Figure 12A] 13 is a diagram showing a previous beacon collection result stored in a storage unit of the parent device. FIG. [Figure 12B] FIG. 13 is a diagram showing beacon collection results currently received by the master unit from each of the first to third slave units. [Figure 13] 4 is a sequence diagram showing a first determination process, a setting process, and a first notification process executed by a control unit of the parent device. FIG. [Figure 14] 11 is a sequence diagram showing a second determination process and a second notification process executed by a control unit of the parent device. FIG. [Figure 15] 13 is a sequence diagram showing a third determination process and a third notification process executed by a control unit of the parent device. FIG. [Figure 16] FIG. 11 is a diagram illustrating a communication system according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of a communication system and a wireless communication terminal of the present invention will be described with reference to the drawings (FIGS. 1 to 16). Note that duplicated explanations may be omitted as appropriate. In addition, the same or corresponding parts in the drawings will be given the same reference symbols and explanations will not be repeated.

[0011] [Embodiment 1] A first embodiment of the present invention will be described below with reference to Figs. 1 to 15. First, a communication system 100 of the present embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing the communication system 100 of the present embodiment. In the present embodiment, the communication system 100 is a telemetry system. Hereinafter, the communication system 100 may be referred to as "telemetry system 100". As shown in Fig. 1, the telemetry system 100 includes a master unit 21, a plurality of slave units 22, and a center device 11 that manages the master unit 21 and the plurality of slave units 22. The center device 11 is an example of a management device.

[0012] The center device 11 is communicatively connected to a wide area wireless network Ne via a center-side network control device 12. The center-side network control device 12 is communicatively connected to a master unit 21 via the wide area wireless network Ne. The center-side network control device 12 is provided, for example, in a public network of a telecommunications carrier. The center-side network control device 12 controls communication between the master unit 21 and the center device 11 via the wide area wireless network Ne.

[0013] The wide area wireless network Ne is, for example, a PHS (Personal Handy-phone System) network, a FOMA (Freedom Of Mobile Multimedia Access) network, an LTE (Long Term Evolution) network, a 4G (Fourth Generation Mobile Communication System) network, or a 5G (Fifth Generation Mobile Communication System) network.

[0014] In the telemeter system 100, communication between the master unit 21 and the slave unit 22, and communication between the slave units 22, for example, is performed using specific low power radio (special low power radio). The frequency band for communication using the special low power radio is, for example, the 920 MHz band. Hereinafter, communication using the special low power radio may be referred to as "special low power radio communication."

[0015] A communication partner (wireless communication terminal) of parent device 21 is determined in advance. Similarly, a communication partner (wireless communication terminal) of child device 22 is determined in advance. Therefore, a communication route between parent device 21 and child device 22 is determined in advance.

[0016] Specifically, parent device 21 and child device 22 store adoption information that specifies the communication partner (wireless communication terminal) of the parent device 21. Parent device 21 communicates with the communication partner specified in the adoption information. Similarly, child device 22 communicates with the communication partner specified in the adoption information. Hereinafter, the communication partner (wireless communication terminal) specified by the adoption information may be referred to as an "adoption terminal."

[0017] In the example shown in FIG. 1, the multiple child devices 22 include the first child device 22a to the third child device 22c. The parent device 21 communicates with the first child device 22a to the third child device 22c. Therefore, the adoption terminals of the parent device 21 include the first child device 22a to the third child device 22c. The adoption terminals of each of the first child device 22a to the third child device 22c include the parent device 21. In this embodiment, the parent device 21 is an example of a "higher wireless communication terminal", and the first child device 22a to the third child device 22c are an example of a "multiple lower wireless communication terminals".

[0018] Next, the detour destination selection process executed by the slave unit 22 will be described. When the slave unit 22 is unable to communicate with the matching terminal due to some reason (for example, an increase in traffic volume around the slave unit 22 or a malfunction), the slave unit 22 executes the detour destination selection process to select a detour destination terminal. Then, the slave unit 22 communicates with the detour destination terminal. Hereinafter, the slave unit 22 that executes the detour destination selection process may be referred to as a "detour route forming terminal."

[0019] The detour route forming terminal (child unit 22) executes the detour destination selection process to select one of the wireless communication terminals installed within the communication distance range (wireless communication range) of the terminal itself as the detour destination terminal. A child unit 22 other than the matched terminal is selected as the detour destination terminal. Hereinafter, a child unit 22 other than the matched terminal among the wireless communication terminals installed within the communication distance range (wireless communication range) of the terminal itself may be referred to as a "detour destination candidate terminal". The detour destination selection process is a process of selecting one of the detour destination candidate terminals as the detour destination terminal. The communication distance of the special low-power wireless communication is 1 m or more and 1000 m or less.

[0020] In this embodiment, the detour route forming terminal (child device 22) selects a detour destination terminal by executing a beacon collection process. In detail, the detour route forming terminal executes a beacon collection process to collect beacon information Be from wireless communication terminals set within the wireless communication range of the detour route forming terminal. Hereinafter, the wireless communication terminals set within the wireless communication range of the detour route forming terminal may be referred to as "terminals within communication range".

[0021] Specifically, the detouring route forming terminal broadcasts a beacon request signal ReB. As a result, the detouring route forming terminal receives beacon information Be from terminals within the communication range. The beacon information Be includes address information, hop count information, and reception field strength information. The address information indicates the address of the wireless communication terminal. The hop count information indicates the number of hops of the wireless communication terminal. The reception field strength information indicates the reception field strength.

[0022] The address is information unique to each wireless communication terminal. In the following description, the unique information may be referred to as "unique information." The hop number indicates the tier from parent device 21 where the wireless communication terminal is. Specifically, parent device 21 is the 0th tier wireless communication terminal. Therefore, the hop number of parent device 21 is "0." First child device 22a to third child device 22c are wireless communication terminals in the first tier. Therefore, the hop number of first child device 22a to third child device 22c is "1."

[0023] The received electric field strength indicates the electric field strength value of the radio wave (radio wave carrying the beacon request signal ReB) received by the terminal within the communication range from the terminal forming the detour route. The electric field strength value is, for example, a received signal strength indicator (RSSI) value.

[0024] The detour route forming terminal selects a detour destination terminal based on the collected beacon information Be. For example, the detour route forming terminal may select, as the detour destination terminal, a detour destination candidate terminal having the highest received electric field strength from among detour destination candidate terminals having the same number of hops as the detour route forming terminal or a number of hops smaller than the detour route forming terminal.

[0025] In the example shown in FIG. 1, the first to third handset 22a to 22c are included within the wireless communication range of the parent device 21. The parent device 21 and the second handset 22b are included within the wireless communication range of the first handset 22a. The parent device 21, the first handset 22a, and the third handset 22c are included within the wireless communication range of the second handset 22b. The parent device 21 and the second handset 22b are included within the wireless communication range of the third handset 22c. Therefore, the detouring destination candidate terminal of the first handset 22a is the second handset 22b. The detouring destination candidate terminals of the second handset 22b are the first handset 22a and the third handset 22c. The detouring destination candidate terminal of the third handset 22c is the second handset 22b.

[0026] For example, when the second handset 22b collects the beacon information Be and finds that the reception field strength of the first handset 22a is greater than that of the third handset 22c, the second handset 22b selects the first handset 22a as the detouring destination terminal.

[0027] Next, the detour destination candidate search process executed by the adopting terminal (child device 22) of parent device 21 will be described. The adopting terminal of parent device 21 executes the detour destination candidate search process to search for detour destination candidate terminals and transmit detour destination candidate information to parent device 21. The detour destination candidate information includes information unique to each of the detour destination candidate terminals (unique information). The detour destination candidate search process is repeatedly executed at a predetermined cycle. The predetermined cycle is, for example, a 45-day cycle. Hereinafter, the predetermined cycle may be referred to as the "first cycle."

[0028] In this embodiment, the association terminal (child device 22) of parent device 21 executes a beacon collection process every time the first period elapses. That is, every time the first period elapses, a beacon request signal ReB is broadcast and beacon information Be is received (collected) from terminals within the communication range. Then, the collected beacon information Be is transmitted to parent device 21 as detouring destination candidate information. Hereinafter, the collected beacon information Be may be referred to as "beacon collection result C." Note that the beacon request signal ReB is an example of a "response request signal," and the address information (unique information) included in the beacon information Be is an example of "response information."

[0029] Specifically, the first child device 22a transmits a beacon collection result C to the parent device 21 based on the beacon information Be received from each of the parent device 21 and the second child device 22b. Similarly, the second child device 22b transmits a beacon collection result C to the parent device 21 based on the beacon information Be received from each of the parent device 21, the first child device 22a, and the third child device 22c. The third child device 22c transmits a beacon collection result C to the parent device 21 based on the beacon information Be received from each of the parent device 21 and the second child device 22b.

[0030] The beacon collection result C includes beacon information Be of a child device 22 having the same or smaller hop number as the child device 22 transmitting the beacon collection result C. However, the beacon collection result C may further include beacon information Be of a child device 22 having a larger hop number than the child device 22 transmitting the beacon collection result C.

[0031] Next, the isolated terminal identification process executed by the parent device 21 will be described. The isolated terminal identification process is a process for searching for a child device 22 that cannot communicate with a detouring destination candidate terminal from among the associated terminals of the parent device 21. Hereinafter, a child device 22 that cannot communicate with a detouring destination candidate terminal may be referred to as an "isolated terminal." An isolated terminal cannot communicate with a detouring destination terminal. Therefore, if an isolated terminal cannot communicate with the parent device 21, it cannot send a message addressed to the center device 11. An isolated terminal is an example of a "second lower wireless communication terminal."

[0032] In the example shown in Fig. 1, the first handset 22a becomes an isolated terminal when it is unable to communicate with the second handset 22b for some reason. The second handset 22b becomes an isolated terminal when it is unable to communicate with either the first handset 22a or the third handset 22c for some reason. The third handset 22c becomes an isolated terminal when it is unable to communicate with the second handset 22b for some reason.

[0033] As already explained, the parent device 21 receives the detour destination candidate information from its own associated terminal. The parent device 21 stores the detour destination candidate information. Then, the parent device 21 compares the stored past detour destination candidate information with the received current detour destination candidate information, and identifies an isolated terminal based on the comparison result. Specifically, the parent device 21 identifies a child device 22 from among its associated terminals that could not receive beacon information Be (response information) from each other, and identifies, as an isolated terminal, a child device 22 from among the identified child devices 22 that cannot communicate with the corresponding detour destination candidate terminal.

[0034] For example, since the only detouring destination candidate terminal for the third handset 22c is the second handset 22b, if the second handset 22b and the third handset 22c are unable to receive beacon information Be from each other, the parent unit 21 identifies the third handset 22c as an isolated terminal.

[0035] In this embodiment, after identifying an isolated terminal, parent device 21 executes a first determination process to determine the wireless communication state with the isolated terminal. Then, if the wireless communication state does not match a predefined condition, parent device 21 executes a first notification process. The first notification process is a process to transmit first notification information Nt1 to center device 11. The first notification information Nt1 indicates that child device 22 identified as an isolated terminal cannot communicate with the corresponding detouring destination candidate terminal.

[0036] For example, the master unit 21 may determine the radio wave conditions between the master unit 21 and the isolated terminal by the first determination process. In detail, the master unit 21 may determine whether the electric field strength of the radio wave received by the isolated terminal from the master unit 21 is equal to or lower than a predetermined threshold. If the electric field strength of the radio wave received by the isolated terminal from the master unit 21 is equal to or lower than the predetermined threshold, the radio wave conditions between the master unit 21 and the isolated terminal are unstable, and therefore communication between the master unit 21 and the isolated terminal may not be possible. If the electric field strength of the radio wave received by the isolated terminal from the master unit 21 is equal to or lower than the predetermined threshold, the master unit 21 transmits first notification information Nt1 addressed to the center device 11 to the center-side network control device 12. As a result, the center device 11 receives the first notification information Nt1.

[0037] In this case, the master unit 21 transmits the first notification information Nt1 to the center device 11 when it identifies an isolated terminal.

[0038] Next, the configuration of the child device 22 will be described with reference to Fig. 1 and Fig. 2. Fig. 2 is a block diagram showing the configuration of the child device 22 included in the communication system 100 of the present embodiment. As shown in Fig. 2, the child device 22 includes a control unit 221, a storage unit 222, a communication unit 223, and a connection unit 224.

[0039] The communication unit 223 performs wireless communication with other wireless communication terminals. For example, as described with reference to FIG. 1, the communication unit 223 establishes a communication connection with the association terminal or the detouring destination terminal, and transmits and receives a message between the association terminal or the detouring destination terminal. Also, as described with reference to FIG. 1, the communication unit 223 transmits a beacon request signal ReB by broadcast, and receives beacon information Be from terminals within the communication range. Furthermore, as described with reference to FIG. 1, the communication unit 223 transmits a beacon collection result C to the parent device 21 as detouring destination candidate information. For example, the communication unit 223 includes a communication module having an RF-LSI for 920 MHz band communication.

[0040] Specifically, the communication unit 223 has an antenna (not shown). The communication unit 223 transmits and receives wireless signals (radio waves) via the antenna. The communication unit 223 converts (decodes) the received wireless signals into signals that can be processed by the control unit 221, and outputs the converted signals to the control unit 221. The communication unit 223 also converts signals output from the control unit 221 to the communication unit 223 into signals that comply with a predetermined wireless communication method (for example, a special low-power radio communication method). This signal is output to the antenna. As a result, the wireless signals (radio waves) are transmitted from the antenna.

[0041] In this embodiment, the communication unit 223 measures the field strength value (received field strength) of the radio wave received by the antenna. The communication unit 223 outputs to the control unit 221 a signal indicating the measured field strength value.

[0042] An electric wire PL, which is connected to the meter 23, is connected to the connection unit 224. Thus, the connection unit 224 is wiredly connected to the meter 23 via the electric wire PL. The meter 23 is installed for each consumer, such as a private home, a company, or various facilities. The meter 23 is a measuring device. The measurement target of the meter 23 is, for example, the usage amount of a resource, such as gas, water, or electricity. The meter 23 measures, for example, the usage amount of a resource, such as gas, water, or electricity, and outputs the measurement result to the electric wire PL.

[0043] The control unit 221 acquires the measurement result from the meter 23 via the electric wire PL and the connection unit 224, and stores data indicating the measurement result in the memory unit 222. The control unit 221 reads out the data indicating the measurement result from the memory unit 222, and creates a telegram addressed to the center indicating the measurement result. The telegram addressed to the center is transmitted to the center device 11. For example, the first slave unit 22a transmits the telegram addressed to the center to the master unit 21 via its own communication unit 223. As a result, the master unit 21 transmits the telegram addressed to the center to the center device 11 via the wide area wireless network Ne and the center-side network control device 12.

[0044] The control unit 221 controls each element of the device itself (child device 22). For example, the control unit 221 controls the storage unit 222 and the communication unit 223. The control unit 221 includes a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The processor controls each element of the device itself (child device 22) by executing a computer program stored in the storage unit 222. Note that the control unit 221 and the storage unit 222 may form a microcomputer.

[0045] The control unit 221 executes various processes. For example, the control unit 221 executes the detouring destination selection process and the detouring destination candidate search process described with reference to Fig. 1. More specifically, the control unit 221 executes the beacon collection process.

[0046] The storage unit 222 stores various data. For example, the storage unit 222 stores its own association information, its own address information, its own hop count information, beacon information Be, and measurement results. The storage unit 222 also stores information indicating the first period described with reference to Fig. 1. The storage unit 222 includes, for example, a semiconductor memory such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a flash memory.

[0047] The storage unit 222 stores various computer programs executed by the control unit 221 (processor). The various computer programs include, for example, a computer program for executing the detour destination selection process and the detour destination candidate search process described with reference to Fig. 1. In this embodiment, the computer program for executing the detour destination selection process and the detour destination candidate search process includes a computer program for executing the beacon collection process described with reference to Fig. 1.

[0048] Next, the configuration of parent device 21 will be described with reference to Fig. 1 and Fig. 3. Fig. 3 is a block diagram showing the configuration of parent device 21 of this embodiment. As shown in Fig. 3, parent device 21 includes control unit 211, storage unit 212, first communication unit 213, and second communication unit 214. Control unit 211 is an example of a processing unit. First communication unit 213 and second communication unit 214 are examples of a transmission unit.

[0049] The first communication unit 213 is communicatively connected to the center device 11. Specifically, the first communication unit 213 communicates with the center-side network control device 12 via the wide-area wireless network Ne. Therefore, the first communication unit 213 is communicatively connected to the center device 11 via the wide-area wireless network Ne and the center-side network control device 12. The first communication unit 213 is a communication module capable of wide-area communication such as a PHS network, a FOMA network, an LTE network, a 4G network, and a 5G network. The first communication unit 213 transmits the measurement result to the center device 11. Also, the first communication unit 213 transmits the first notification information Nt1 to the center device 11 as described with reference to FIG. 1.

[0050] The second communication unit 214 performs wireless communication with the adoption terminal. The second communication unit 214 includes, for example, a communication module having an RF-LSI for 920 MHz band communication. The second communication unit 214 establishes a communication connection with the adoption terminal and transmits and receives a message with the adoption terminal. For example, the second communication unit 214 receives a measurement result from the adoption terminal. In addition, the second communication unit 214 transmits a beacon request signal ReB by broadcast and receives beacon information Be from a terminal within the communication range. Furthermore, the second communication unit 214 receives a beacon collection result C from the adoption terminal as detour destination candidate information, as described with reference to FIG. 1.

[0051] The control unit 211 controls each element of the device itself (parent device 21). For example, the control unit 211 controls the storage unit 212, the first communication unit 213, and the second communication unit 214. The control unit 211 includes a processor such as a CPU or an MPU. The processor controls each element of the device itself (parent device 21) by executing a computer program stored in the storage unit 212. Note that the control unit 211 and the storage unit 212 may form a microcomputer.

[0052] The control unit 211 executes various processes. For example, the control unit 211 executes a beacon collection process. The control unit 211 also executes an isolated terminal identification process and a first determination process described with reference to Fig. 1. Furthermore, the control unit 221 executes a first notification process as described with reference to Fig. 1, and transmits first notification information Nt1 to the center device 11.

[0053] The storage unit 212 stores various data. For example, the storage unit 212 stores its own association information, its own address information, and its own hop count information. Furthermore, the storage unit 212 stores the beacon collection result C (detouring destination candidate information) described with reference to Fig. 1. The storage unit 212 includes, for example, a semiconductor memory such as a ROM, a RAM, and a flash memory.

[0054] The storage unit 212 stores various computer programs executed by the control unit 211 (processor). For example, the various computer programs include a computer program for executing a beacon collection process. The various computer programs also include a computer program for executing an isolated terminal identification process and a first determination process described with reference to Fig. 1. Furthermore, the various computer programs also include a computer program for executing a first notification process.

[0055] Next, the process executed by the control unit 211 of the parent device 21 of this embodiment will be described with reference to Fig. 1 to Fig. 4. Fig. 4 is a flowchart showing the process executed by the control unit 211 of the parent device 21 of this embodiment. The process shown in Fig. 4 starts when the parent device 21 receives a beacon collection result C from the adoption terminal.

[0056] When the control unit 211 receives the beacon collection result C transmitted from the adopting terminal via the second communication unit 214, it executes the isolated terminal identification process described with reference to Fig. 1. In this embodiment, the control unit 211 first determines whether the previous beacon collection result C stored in the storage unit 212 matches the currently received beacon collection result C (step S1). Note that the previous beacon collection result C is the beacon collection result C acquired when the adopting terminals of the parent device 21 do not include an isolated terminal.

[0057] When the control unit 211 determines that the previous beacon collection result C and the current beacon collection result C match (Yes in step S1), the control unit 211 ends the process shown in Fig. 4. When the control unit 211 determines that the previous beacon collection result C and the current beacon collection result C do not match (No in step S1), the control unit 211 identifies an isolated terminal (step S2).

[0058] Specifically, the control unit 211 compares the previous beacon collection result C with the current beacon collection result C to identify the child devices 22 that could not receive the beacon information Be from each other, and identifies the child devices 22 that cannot communicate with the corresponding detouring destination candidate terminal as isolated terminals from among the identified child devices 22. Hereinafter, the child devices 22 that could not receive the beacon information Be from each other may be referred to as "monitoring target terminals."

[0059] In addition, if the previous beacon collection result C and the current beacon collection result C do not match, the control unit 211 does not store the current beacon collection result C in the memory unit 212. Therefore, the memory unit 212 holds the previous beacon collection result C (the beacon collection result C acquired when the parent device 21 does not include an isolated terminal in its associated terminals).

[0060] After identifying the isolated terminal, the control unit 211 executes the first determination process described with reference to Fig. 1. Specifically, the control unit 211 transmits a radio wave measurement request signal ReM to the isolated terminal. The radio wave measurement request signal ReM is a signal requesting received electric field strength information M. When the communication unit 223 of the isolated terminal (child device 22) receives the radio wave measurement request signal ReM, it measures the electric field strength value of the radio wave carrying the radio wave measurement request signal ReM. Based on the radio wave measurement request signal ReM, the control unit 221 of the isolated terminal (child device 22) transmits the received electric field strength information M indicating the measured electric field strength value to the parent device 21 via the communication unit 223. When the control unit 211 of the parent device 21 acquires the received electric field strength information M via the second communication unit 214, it determines whether the electric field strength value is equal to or less than a threshold (step S3).

[0061] If the control unit 211 determines that the field strength value is not equal to or less than the threshold value (No in step S3), it ends the process shown in Fig. 4. If the control unit 211 determines that the field strength value is equal to or less than the threshold value (Yes in step S3), it executes the first notification process described with reference to Figs. 1 and 2, and transmits first notification information Nt1 to the center device 11 (step S4). As a result, it is possible to notify the administrator of the center device 11 that the telemeter system 100 includes an isolated terminal, and that the radio wave environment of the isolated terminal is unstable.

[0062] In this embodiment, the control unit 211 executes a setting process after transmitting the first notification information Nt1 (step S5). The setting process is a process of changing the cycle in which the monitored terminal executes the detouring destination candidate search process to a second cycle that is shorter than the first cycle. For example, if the first cycle is a 45-day cycle, the second cycle may be a 7-day cycle. After executing the setting process, the control unit 221 ends the process shown in FIG. 4.

[0063] In detail, the control unit 211 transmits a setting signal Set to the monitoring target terminal via the second communication unit 214. The setting signal Set indicates an instruction to change the first cycle to the second cycle, and indicates the number of executions N, which is the number of times to execute the detouring destination candidate search process in the second cycle. The number of executions N is, for example, 4 or 5 times.

[0064] When the control unit 221 of the terminal to be monitored (child device 22) receives the setting signal Set via the communication unit 223, it changes the cycle of the detour destination candidate search process from the first cycle to the second cycle based on the setting signal Set. Specifically, it stores the second cycle in the memory unit 222. Also, the control unit 221 of the terminal to be monitored (child device 22) stores the number of executions N in the memory unit 222 based on the setting signal Set. As a result, the terminal to be monitored executes the detour destination candidate search process N times in the second cycle.

[0065] The setting process may be executed after the first notification process is executed.

[0066] Next, the second determination process, the second notification process, the third determination process, and the third notification process executed by the control unit 211 of the master device 21 of this embodiment will be described with reference to Fig. 1 to Fig. 3 and Fig. 5. Fig. 5 is a flowchart showing the second determination process, the second notification process, the third determination process, and the third notification process executed by the control unit 211 of the master device 21 of this embodiment. The process shown in Fig. 5 starts when the master device 21 receives a beacon collection result C from the terminal to be monitored.

[0067] When the control unit 211 receives the beacon collection result C transmitted from the monitored terminal via the second communication unit 214, it determines whether the isolated terminal is able to communicate with the detouring destination candidate terminal. Specifically, the control unit 211 determines whether the beacon collection result C of the monitored terminal stored in the storage unit 212 matches the current beacon collection result C acquired from the monitored terminal (step S11).

[0068] As described with reference to FIG. 4, the beacon collection result C stored in the storage unit 212 is the beacon collection result C acquired when the associated terminals of the parent device 21 do not include an isolated terminal.

[0069] If the control unit 211 determines that the beacon collection result C of the monitored terminal stored in the memory unit 212 matches the current beacon collection result C acquired from the monitored terminal (Yes in step S11), it executes a second determination process.

[0070] Specifically, the control unit 211 determines whether the number of consecutive matches between the beacon collection result C of the monitored terminal stored in the storage unit 212 and the current beacon collection result C acquired from the monitored terminal has reached N2 times (step S12). Here, N2 is an integer equal to or greater than 2, and is stored in advance in the storage unit 212. N2 times may indicate the same value as the number of executions N, or may indicate a value different from the number of executions N.

[0071] If it is determined that the number of consecutive matches between the beacon collection result C of the monitored terminal stored in the memory unit 212 and the current beacon collection result C obtained from the monitored terminal has not reached N2 (No in step S12), the control unit 211 terminates the processing shown in FIG. 5.

[0072] If it is determined that the number of consecutive matches between the beacon collection result C of the monitored terminal stored in the memory unit 212 and the current beacon collection result C obtained from the monitored terminal has reached N2 (Yes in step S12), the control unit 211 executes a second notification process (step S13) and terminates the process shown in Figure 5.

[0073] The second notification process is a process of transmitting second notification information Nt2 to the center device 11. The second notification information Nt2 indicates that the isolated terminal is now able to communicate with the detouring destination candidate terminal. In other words, the second notification information Nt2 indicates that the isolated terminal has recovered from the isolated state.

[0074] On the other hand, if the control unit 211 determines that the beacon collection result C of the monitored terminal stored in the memory unit 212 does not match the current beacon collection result C acquired from the monitored terminal (No in step S11), it executes a third determination process.

[0075] Specifically, the control unit 211 determines whether the number of times that the beacon collection result C of the monitored terminal stored in the storage unit 212 does not match the current beacon collection result C acquired from the monitored terminal has reached N3 times (step S14). Here, N3 is an integer equal to or greater than 2, and is stored in advance in the storage unit 212. N3 times may indicate the same value as the number of executions N, or may indicate a value different from the number of executions N. Furthermore, N3 times may indicate the same value as N1 times, or may indicate a value different from N1 times.

[0076] If it is determined that the number of times that the beacon collection result C of the monitored terminal stored in the memory unit 212 does not match the current beacon collection result C obtained from the monitored terminal does not reach N3 (No in step S14), the control unit 211 terminates the processing shown in Figure 5.

[0077] If it is determined that the number of times that the beacon collection result C of the monitored terminal stored in the memory unit 212 does not match the current beacon collection result C obtained from the monitored terminal has reached N3 (Yes in step S14), the control unit 211 executes a third notification process (step S15) and terminates the process shown in FIG. 5.

[0078] The third notification process is a process of transmitting third notification information Nt3 to the center device 11. The third notification information Nt3 indicates, for example, that the isolated terminal is broken. In other words, the control unit 211 may transmit a failure notification to the center device 11.

[0079] After the monitored terminal executes the detour destination candidate search process N times in the second cycle, master unit 21 transmits to the monitored terminal a setting signal for returning the cycle of the detour destination candidate search process from the second cycle to the first cycle.

[0080] Next, an example of the operation of the parent unit 21 and the first to third child units 22a to 22c will be described with reference to Fig. 1 to Fig. 15. First, an example of the operation of the parent unit 21 and the first to third child units 22a to 22c will be described with reference to Fig. 6 to Fig. 9.

[0081] 6 is a sequence diagram showing a beacon collection process executed by the control unit 211 of the parent device 21. As shown in FIG. 6, the control unit 211 of the parent device 21 broadcasts a beacon request signal ReB via the second communication unit 214. As a result, the control unit 211 of the parent device 21 receives beacon information Be from each of the first child device 22a to the third child device 22c via the second communication unit 214. The control unit 211 of the parent device 21 stores a beacon collection result C of the parent device 21 in the storage unit 212.

[0082] The beacon collection result C of the master unit 21 indicates that the master unit 21 can communicate with the first slave unit 22a to the third slave unit 22c. Specifically, the beacon collection result C of the master unit 21 includes unique information (address information) of each of the first slave unit 22a to the third slave unit 22c.

[0083] Fig. 7 is a sequence diagram showing a detouring destination candidate search process executed by the control unit 221 of the first handset 22a. As shown in Fig. 7, the control unit 221 of the first handset 22a broadcasts a beacon request signal ReB via the communication unit 223. As a result, the control unit 221 of the first handset 22a receives beacon information Be from each of the parent unit 21 and the second handset 22b via the communication unit 223.

[0084] When the control unit 221 of the first child device 22a receives the beacon information Be, it transmits a beacon collection result C to the parent device 21. The control unit 211 of the parent device 21 stores in the storage unit 212 the beacon collection result C of the first child device 22a.

[0085] The beacon collection result C of the first child device 22a indicates that the first child device 22a can communicate with the parent device 21 and the second child device 22b. Specifically, the beacon collection result C of the first child device 22a includes unique information (address information) of each of the parent device 21 and the second child device 22b.

[0086] Fig. 8 is a sequence diagram showing a detouring destination candidate search process executed by the control unit 221 of the second handset 22b. As shown in Fig. 8, the control unit 221 of the second handset 22b broadcasts a beacon request signal ReB via the communication unit 223. As a result, the control unit 221 of the second handset 22b receives beacon information Be from each of the parent unit 21, the first handset 22a, and the third handset 22c via the communication unit 223.

[0087] When the control unit 221 of the second child device 22b receives the beacon information Be, it transmits a beacon collection result C to the parent device 21. The control unit 211 of the parent device 21 stores in the storage unit 212 the beacon collection result C of the second child device 22b.

[0088] The beacon collection result C of the second child device 22b indicates that the second child device 22b can communicate with the parent device 21, the first child device 22a, and the third child device 22c. Specifically, the beacon collection result C of the second child device 22b includes unique information (address information) of each of the parent device 21, the first child device 22a, and the third child device 22c.

[0089] Fig. 9 is a sequence diagram showing a detouring destination candidate search process executed by the control unit 221 of the third handset 22c. As shown in Fig. 9, the control unit 221 of the third handset 22c broadcasts a beacon request signal ReB via the communication unit 223. As a result, the control unit 221 of the third handset 22c receives beacon information Be from each of the parent unit 21 and the second handset 22b via the communication unit 223.

[0090] When the control unit 221 of the third slave unit 22c receives the beacon information Be, it transmits a beacon collection result C to the master unit 21. The control unit 211 of the master unit 21 stores in the storage unit 212 the beacon collection result C of the third slave unit 22c.

[0091] The beacon collection result C of the third child device 22c indicates that the third child device 22c can communicate with the parent device 21 and the second child device 22b. Specifically, the beacon collection result C of the third child device 22c includes unique information (address information) of each of the parent device 21 and the second child device 22b.

[0092] Next, with reference to Figures 10 and 11, we will explain the operations of the parent unit 21, the second handset 22b, and the third handset 22c when communication cannot be performed between the second handset 22b and the third handset 22c for some reason.

[0093] Fig. 10 is another sequence diagram showing the detour destination candidate search process executed by the control unit 221 of the second handset 22b. As shown in Fig. 10, the control unit 221 of the second handset 22b broadcasts a beacon request signal ReB via the communication unit 223. If communication between the second handset 22b and the third handset 22c cannot be performed due to some reason, the communication unit 223 of the second handset 22b does not receive the beacon information Be from the third handset 22c. Therefore, the control unit 221 of the second handset 22b receives the beacon information Be from each of the parent unit 21 and the first handset 22a via the communication unit 223.

[0094] When the control unit 221 of the second child device 22b receives the beacon information Be, it transmits a beacon collection result C to the parent device 21. The control unit 211 of the parent device 21 stores in the storage unit 212 the beacon collection result C of the second child device 22b.

[0095] If communication between the second child device 22b and the third child device 22c cannot be performed due to some reason, the beacon collection result C of the second child device 22b indicates that the second child device 22b can communicate with the parent device 21 and the first child device 22a. Specifically, the beacon collection result C of the second child device 22b includes unique information (address information) of each of the parent device 21 and the first child device 22a.

[0096] 11 is another sequence diagram showing the detouring destination candidate search process executed by the control unit 221 of the third handset 22c. As shown in FIG. 11, the control unit 221 of the third handset 22c broadcasts a beacon request signal ReB via the communication unit 223. If communication between the second handset 22b and the third handset 22c cannot be performed due to some reason, the communication unit 223 of the third handset 22c does not receive the beacon information Be from the second handset 22b. Therefore, the control unit 221 of the third handset 22c receives the beacon information Be from the parent unit 21 via the communication unit 223.

[0097] When the control unit 221 of the third slave unit 22c receives the beacon information Be, it transmits a beacon collection result C to the master unit 21. The control unit 211 of the master unit 21 stores in the storage unit 212 the beacon collection result C of the third slave unit 22c.

[0098] If communication cannot be performed between the second handset 22b and the third handset 22c for some reason, the beacon collection result C of the third handset 22c indicates that the third handset 22c can communicate with the parent device 21. Specifically, the beacon collection result C of the third handset 22c includes unique information (address information) of the parent device 21.

[0099] Next, the isolated terminal identification process executed by the control unit 211 of the parent device 21 will be described with reference to Fig. 12A and Fig. 12B. Fig. 12A is a diagram showing the previous beacon collection result C stored in the storage unit 212 of the parent device 21. Fig. 12B is a diagram showing the beacon collection result C received this time by the parent device 21 from each of the first child device 22a to the third child device 22c. In detail, Fig. 12A shows the beacon collection result C acquired by the parent device 21 when the adoption terminals of the parent device 21 do not include an isolated terminal. Fig. 12B shows the beacon collection result C acquired by the parent device 21 when communication cannot be performed between the second child device 22b and the third child device 22c for some reason.

[0100] 12A and 12B, if communication cannot be performed between the second handset 22b and the third handset 22c for some reason, the unique information of the third handset 22c disappears from the beacon collection result C of the second handset 22b, and the unique information of the second handset 22b disappears from the beacon collection result C of the third handset 22c. Therefore, the control unit 221 of the master unit 21 compares the previous beacon collection result C stored in the storage unit 212 with the beacon collection result C received this time, thereby identifying the second handset 22b and the third handset 22c as the handset 22 that could not receive the beacon information Be (response information) from each other.

[0101] 12B, the second child device 22b is not an isolated terminal because it can communicate with the first child device 22a. On the other hand, the third child device 22c cannot communicate with other child devices 22 that have the same hop count or a hop count smaller than that of the third child device 22c. Therefore, the control unit 211 of the parent device 21 identifies the third child device 22c as an isolated terminal based on the beacon collection result C received this time.

[0102] Next, the first determination process, the setting process, and the first notification process executed by the control unit 211 of the parent device 21 will be described with reference to Fig. 13. Fig. 13 is a sequence diagram showing the first determination process, the setting process, and the first notification process executed by the control unit 211 of the parent device 21.

[0103] 13, when the control unit 211 of the parent device 21 identifies the third child device 22c as an isolated terminal, the control unit 211 transmits a radio wave measurement request signal ReM to the third child device 22c. As a result, the control unit 211 of the parent device 21 receives the reception field intensity information M from the third child device 22c via the second communication unit 214.

[0104] When the control unit 211 of the parent device 21 receives the reception electric field strength information M, it determines whether or not the electric field strength value is equal to or less than the threshold value. When the control unit 211 of the parent device 21 determines that the electric field strength value is equal to or less than the threshold value, it transmits a setting signal Set to the second handset 22b and the third handset 22c, which are the terminals to be monitored. As a result, the cycle in which the second handset 22b and the third handset 22c execute the detour destination candidate search process is changed from the first cycle to the second cycle. In addition, the number of times that the second handset 22b and the third handset 22c execute the detour destination candidate search process in the second cycle is set to N times.

[0105] In the example shown in FIG. 13, the control unit 211 of the master unit 21 executes a first notification process after executing a setting process, and transmits first notification information Nt1 to the center device 11.

[0106] Next, the second determination process and the second notification process executed by the control unit 211 of the parent device 21 will be described with reference to Fig. 14. Fig. 14 is a sequence diagram showing the second determination process and the second notification process executed by the control unit 211 of the parent device 21.

[0107] In the example shown in Fig. 14, N2 times is 2. As shown in Fig. 14, when the number of consecutive matches between the beacon collection result C (see Fig. 12A) of the monitored terminals (second slave 22b and third slave 22c) stored in the memory unit 212 of the master 21 and the current beacon collection result C acquired from the monitored terminal reaches 2 (N2 times), the control unit 211 of the master 21 executes the second notification process and transmits the second notification information Nt2 to the center device 11.

[0108] Next, the third determination process and the third notification process executed by the control unit 211 of the parent device 21 will be described with reference to Fig. 15. Fig. 15 is a sequence diagram showing the third determination process and the third notification process executed by the control unit 211 of the parent device 21.

[0109] In the example shown in Fig. 15, N3 times is N times. As shown in Fig. 15, when the number of times that the beacon collection result C (see Fig. 12A) of the monitored terminals (second slave 22b and third slave 22c) stored in the memory unit 212 of the master 21 does not match the current beacon collection result C acquired from the monitored terminal reaches N times (N3 times), the control unit 211 of the master 21 executes a third notification process and transmits third notification information Nt3 to the center device 11.

[0110] The first embodiment of the present invention has been described above with reference to Fig. 1 to Fig. 15. According to this embodiment, when communication with a related terminal cannot be performed due to some reason, it is possible to know in advance child device 22 (isolated terminal) that cannot be detoured.

[0111] Furthermore, according to this embodiment, the first determination process makes it possible to grasp in advance isolated terminals that are more likely to be unable to communicate with an associated terminal.

[0112] Furthermore, according to the present embodiment, the period of the detouring destination candidate search process performed by the monitored terminal can be temporarily shortened by the setting process, so that it is possible to check earlier whether the deterioration of the radio wave environment is temporary.

[0113] In this embodiment, in the first judgment process, the parent unit 21 judges the radio wave conditions between the parent unit 21 and the isolated terminal based on the received electric field strength of the isolated terminal, but the radio wave conditions between the parent unit 21 and the isolated terminal may also be judged based on the electric field strength of the radio waves received by the parent unit 21 from the isolated terminal.

[0114] In addition, in this embodiment, parent device 21 executes the setting process once, but parent device 21 may execute the setting process multiple times to gradually bring the cycle of the detour destination candidate search process closer to the first cycle from the second cycle. For example, parent device 21 may set a third cycle that is shorter than the first cycle and longer than the second cycle after the monitored terminal executes the detour destination candidate search process N times in the second cycle. For example, if the first cycle is a 45-day cycle and the second cycle is a 7-day cycle, the third cycle may be a 15-day cycle.

[0115] In addition, in this embodiment, the parent device 21 executes the second determination process and the third determination process, but both or one of the second determination process and the third determination process may be omitted.

[0116] In the present embodiment, the parent device 21 executes the second notification process when the number of consecutive matches between the beacon collection result C of the monitoring target terminal stored in the storage unit 212 of the parent device 21 and the current beacon collection result C acquired from the monitoring target terminal reaches N2 times. However, the parent device 21 may determine whether or not the current beacon collection result C acquired from the isolated terminal includes a child device 22 other than the wireless communication terminal included in the beacon collection result C of the isolated terminal stored in the storage unit 212. In this case, the parent device 21 executes the second notification process when the number of times it is determined that the current beacon collection result C acquired from the isolated terminal includes a child device 22 other than the wireless communication terminal included in the beacon collection result C of the isolated terminal stored in the storage unit 212 reaches N2 times. For example, when the third child device 22c is an isolated terminal, the parent device 21 determines whether or not the beacon collection result C acquired from the third child device 22c includes a child device 22 other than the parent device 21 and the second child device 22b. Here, the handset 22 different from the parent device 21 and the second handset 22b is, for example, a handset 22 newly installed within the wireless communication range of the third handset 22c.

[0117] Furthermore, in this embodiment, the parent unit 21 executes the third notification process when the number of times that the beacon collection result C of the monitored terminal stored in the memory unit 212 of the parent unit 21 does not match the current beacon collection result C acquired from the monitored terminal reaches N3 times, but the parent unit 21 may execute the third notification process when the number of times that the parent unit 21 determines that the current beacon collection result C acquired from the isolated terminal does not include a child unit 22 other than the wireless communication terminal included in the beacon collection result C of the isolated terminal stored in the memory unit 212 reaches N3 times.

[0118] [Embodiment 2] Next, a second embodiment of the present invention will be described with reference to Fig. 16. However, only differences from the first embodiment will be described, and a description of the same matters as in the first embodiment will be omitted. The second embodiment differs from the first embodiment in that the child device 22 executes the isolated terminal identification process.

[0119] 16 is a diagram showing a communication system 100 according to the present embodiment. As shown in FIG. 16, the communication system 100 (telemetry system) includes a master unit 21, a plurality of slave units 22, and a center device 11.

[0120] In the example shown in FIG. 16, the multiple child devices 22 include a first child device 22d, a second child device 22d1, a third child device 22d2, and a fourth child device 22d3. The parent device 21 communicates with the first child device 22d. Therefore, the adoption terminal of the parent device 21 includes the first child device 22d. The adoption terminals of each of the second child device 22d1 to the fourth child device 22d3 include the first child device 22d. In this embodiment, the first child device 22d is an example of a "higher wireless communication terminal", and the second child device 22d1 to the fourth child device 22d3 are examples of a "multiple lower wireless communication terminals".

[0121] Each of the second handset 22d1 to the fourth handset 22d3 executes a detour destination candidate search process and transmits detour destination candidate information to the first handset 22d. In this embodiment, the detour destination candidate information is the beacon collection result C.

[0122] The first handset 22d executes an isolated terminal identification process. Therefore, the first handset 22d identifies an isolated terminal from among the second handset 22d1 to the fourth handset 22d3 based on the beacon collection result C (detouring destination candidate information) received from each of the second handset 22d1 to the fourth handset 22d3.

[0123] When the first slave unit 22d identifies the isolated terminal, it executes a first determination process. Then, when the wireless communication state between the first slave unit 22d and the isolated terminal does not match a predetermined condition, it executes a first notification process and transmits the first notification information Nt1 addressed to the center device 11 to the master unit 21. As a result, the center device 11 receives the first notification information Nt1.

[0124] The first slave device 22d further executes a setting process to change the cycle in which the monitored terminal executes the detour destination candidate search process to a second cycle that is shorter than the first cycle. After that, the first slave device 22d determines whether the isolated terminal is able to communicate with the detour destination candidate terminal.

[0125] When the isolated terminal becomes able to communicate with the detouring destination candidate terminal, the first slave unit 22d executes a second notification process and transmits second notification information Nt2 addressed to the center device 11 to the master unit 21. On the other hand, when the isolated terminal does not become able to communicate with the detouring destination candidate terminal, the first slave unit 22d executes a third notification process and transmits third notification information Nt3 addressed to the center device 11 to the master unit 21.

[0126] The second embodiment of the present invention has been described above with reference to Fig. 16. According to this embodiment, it is possible to know in advance child device 22 (isolated terminal) that cannot be bypassed when communication with a related terminal cannot be performed due to some reason.

[0127] The embodiments of the present invention have been described above with reference to the drawings (FIGS. 1 to 16). However, the present invention is not limited to the above embodiments, and can be implemented in various aspects without departing from the gist of the present invention. In addition, the components disclosed in the above embodiments can be modified as appropriate. For example, a certain component among all the components shown in one embodiment may be added to a component of another embodiment, or some of all the components shown in one embodiment may be deleted from the embodiment.

[0128] The drawings are mainly schematic illustrations of each component to facilitate understanding of the invention, and the thickness, length, number, spacing, etc. of each component shown in the drawings may differ from the actual ones due to the convenience of creating the drawings. Furthermore, the configurations of each component shown in the above embodiment are merely examples and are not particularly limited, and it goes without saying that various modifications are possible within a range that does not substantially deviate from the effects of the present invention.

[0129] For example, in the embodiment described with reference to FIGS. 1 to 16, the meter 23 is not connected to the master unit 21, but the meter 23 may be connected to the master unit 21.

[0130] 1 to 16, the slave unit 22 and the meter 23 are connected by wires PL, but the slave unit 22 and the meter 23 may be connected wirelessly. Similarly, the master unit 21 and the meter 23 may be connected wirelessly. [Industrial Applicability]

[0131] The present invention provides a communication system and a wireless communication terminal, and has industrial applicability. [Explanation of symbols]

[0132] 11: Center device 21: Parent unit 22: Child unit 100: Communication system (telemetry system) 211: Control unit 212: Storage section Be: Beacon information C: Beacon collection results M: Reception field strength information N: Number of executions Nt1: 1st notification information Nt2 :Second notification information Nt3: Third notification information ReB: Beacon request signal ReM: Radio wave measurement request signal Set: Setting signal

Claims

1. A communication system including a plurality of lower wireless communication terminals and an upper wireless communication terminal that communicates with the plurality of lower wireless communication terminals, each of the plurality of lower wireless communication terminals broadcasts a response request signal, receives response information from other lower wireless communication terminals that are detouring destination candidate terminals within a wireless communication range of the terminal, and transmits the received response information to the upper wireless communication terminal, the response information including information unique to each of the other lower wireless communication terminals; The upper wireless communication terminal includes: a storage unit that stores the response information received from each of the plurality of lower-level wireless communication terminals; a processing unit that specifies, from among the plurality of lower wireless communication terminals, a first lower wireless communication terminal from which the response information cannot be received from each other based on the response information stored in the storage unit and the current response information received from each of the plurality of lower wireless communication terminals, and specifies, from among the specified first lower wireless communication terminals, a second lower wireless communication terminal that cannot communicate with the corresponding detouring destination candidate terminal; A communication system comprising:

2. a management device for managing the upper wireless communication terminal and the plurality of lower wireless communication terminals, 2. The communication system according to claim 1, wherein the upper wireless communication terminal further comprises a transmission unit that transmits, to the management device, information indicating that communication cannot be performed between the second lower wireless communication terminal and the corresponding detouring destination candidate terminal.

3. 3. The communication system according to claim 2, wherein the processing unit determines whether the second lower wireless communication terminal has been able to communicate with the corresponding detouring destination candidate terminal based on the response information stored in the memory unit and the current response information received from each of the first lower wireless communication terminals, and when the second lower wireless communication terminal has been able to communicate with the corresponding detouring destination candidate terminal, transmits information indicating that the second lower wireless communication terminal can communicate with the corresponding detouring destination candidate terminal via the transmission unit to the management device.

4. 4. The communication system according to claim 2 or claim 3, wherein the processing unit determines a wireless communication state between the second lower wireless communication terminal, and if the wireless communication state does not match a predefined condition, transmits information to the management device via the transmission unit indicating that the second lower wireless communication terminal cannot communicate with the corresponding detouring destination candidate terminal.

5. each of the plurality of lower-level wireless communication terminals transmits the response request signal in a first period that is defined in advance; 5. The communication system according to claim 4, wherein when the wireless communication state does not match the condition, the processing unit transmits, via the transmitting unit, a signal to the first lower wireless communication terminal, which sets a period for transmitting the response request signal to a second period shorter than the first period.

6. The communication system according to claim 5 , wherein the first lower wireless communication terminal transmits the response request signal a predetermined number of times in the second period.

7. 7. The communication system according to claim 6, wherein the processing unit transmits, via the transmitting unit, to the first lower wireless communication terminal a signal that sets the period for transmitting the response request signal to a third period that is longer than the second period and shorter than the first period, after the first lower wireless communication terminal transmits the response request signal in the second period the predetermined number of times.

8. A wireless communication terminal that communicates with a plurality of lower-level wireless communication terminals, each of the plurality of lower wireless communication terminals broadcasts a response request signal, receives response information from other lower wireless communication terminals that are detouring destination candidate terminals within a wireless communication range of the terminal, and transmits the received response information to the wireless communication terminal, the response information including information unique to each of the other lower wireless communication terminals; The wireless communication terminal includes: a storage unit that stores the response information received from each of the plurality of lower-level wireless communication terminals; a processing unit that specifies, from among the plurality of lower wireless communication terminals, a first lower wireless communication terminal from which the response information cannot be received from each other based on the response information stored in the storage unit and the current response information received from each of the plurality of lower wireless communication terminals, and specifies, from among the specified first lower wireless communication terminals, a second lower wireless communication terminal that cannot communicate with the corresponding detouring destination candidate terminal; A wireless communication terminal comprising:

Images