Wireless communication system, method for managing wireless communication system, and management device

Abstract

To provide a wireless communication system capable of suppressing excessive use of relay devices.SOLUTION: A wireless communication system includes: a high-level communication device that receives sensor data via 802.11ah wireless communication; a relay device that relays the sensor data to the high-level communication device via 802.11ah wireless communication; a plurality of sensor terminals that transmit the sensor data to the relay device via 802.11ah wireless communication; and a server having a frequency management unit that decreases the transmission frequency of sensor data of other sensor terminals when the transmission frequency of sensor data of one of the plurality of sensor terminals increases.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wireless communication system, a management method of a wireless communication system, and a management device.

Background Art

[0002] In Patent Document 1, when realizing the role of a gateway between a sensor and a server, a technique is disclosed in which data is aggregated between gateways in consideration of transmission time limits, and the number of simultaneous connections to mobile communication by the gateway is reduced.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the 920 MHz band in Japan where IEEE standard 802.11ah can be used, the transmission time per unit time (also referred to as transmission duty) is limited to 10% by the Radio Law.

[0005] In a wireless communication system in which sensor data from a plurality of sensor terminals is transmitted to a higher-level communication device via a relay device, the transmission frequency of the sensor data may vary according to the urgency level or the like. If the transmission frequency increases excessively, the transmission time of the relay device may exceed the limit.

[0006] The present invention has been made in view of the above problems, and its main object is to provide a wireless communication system, a management method of a wireless communication system, and a management device capable of suppressing excessive use of a relay device.

Means for Solving the Problems

[0007] To solve the above problems, a wireless communication system according to one aspect of the present invention comprises: a higher-level communication device that receives sensor data via 802.11ah wireless communication; a relay device that relays the sensor data to the higher-level communication device via 802.11ah wireless communication; a plurality of sensor terminals that transmit the sensor data to the relay device via 802.11ah wireless communication; and a server having a frequency management unit that reduces the transmission frequency of sensor data of other sensor terminals when the transmission frequency of sensor data of one of the plurality of sensor terminals increases. This makes it possible to suppress excessive use of the relay device.

[0008] In the above embodiment, the frequency management unit may stop the transmission of sensor data from the other sensor terminals. This makes it possible to further suppress excessive use of the relay device.

[0009] In the above embodiment, the frequency management unit may monitor the transmission frequency of the sensor data from the plurality of sensor terminals, and if the transmission frequency of the sensor data from one sensor terminal increases, it may decrease the transmission frequency of the sensor data from the other sensor terminals. This makes it possible to monitor the transmission frequency of sensor data and detect an increase in the transmission frequency of sensor data.

[0010] In the above embodiment, the frequency management unit may reduce the transmission frequency of sensor data from other sensor terminals when it receives notification from one sensor terminal that the transmission frequency of sensor data has increased. This makes it possible to detect an increase in the transmission frequency of sensor data by receiving notifications from sensor terminals.

[0011] In the above embodiment, the plurality of sensor terminals may increase the frequency of transmitting the sensor data when an emergency condition is detected. This makes it possible to increase the frequency of transmitting sensor data when an emergency condition is detected.

[0012] In the above embodiment, the frequency management unit may determine the degree of urgency based on the sensor data of the plurality of sensor terminals and notify sensor terminals with a degree of urgency above a predetermined level of emergency status. This makes it possible for the frequency management unit to notify sensor terminals of emergency status.

[0013] In the above embodiment, the plurality of sensor terminals may determine the degree of urgency based on the sensor data and detect an emergency state if the degree of urgency is above a predetermined level. This makes it possible for the sensor terminals to detect an emergency state on their own.

[0014] In the above embodiment, if the frequency of transmission of sensor data from one sensor terminal increases, the frequency of transmission of sensor data from sensor terminals with a low level of urgency, as determined based on the sensor data, may be reduced. This makes it possible to reduce the transmission frequency of sensor terminals with a low level of urgency.

[0015] Furthermore, in another aspect of the present invention, a method for managing a wireless communication system comprises a higher-level communication device that receives sensor data via 802.11ah wireless communication, a relay device that relays the sensor data to the higher-level communication device via 802.11ah wireless communication, and a plurality of sensor terminals that transmit the sensor data to the relay device via 802.11ah wireless communication. In this wireless communication system, when the transmission frequency of the sensor data from one of the plurality of sensor terminals increases, the transmission frequency of the sensor data from the other sensor terminals is reduced. This makes it possible to suppress excessive use of the relay device.

[0016] In addition, a management device according to another aspect of the present invention includes an upper communication device that receives sensor data by 802.11ah wireless communication, a relay device that relays the sensor data to the upper communication device by 802.11ah wireless communication, and a plurality of sensor terminals that transmit the sensor data to the relay device by 802.11ah wireless communication. When the transmission frequency of the sensor data of one of the plurality of sensor terminals increases, a change unit that decreases the transmission frequency of the sensor data of other sensor terminals is provided. According to this, it is possible to suppress excessive use of the relay device.

Brief Description of Drawings

[0017] [Figure 1] It is a diagram showing a configuration example of a wireless communication system. [Figure 2] It is a diagram showing a configuration example of an access point. [Figure 3] It is a diagram showing a configuration example of a relay device. [Figure 4] It is a diagram showing a configuration example of a sensor terminal. [Figure 5] It is a diagram showing an example of pairing data for an access point. [Figure 6] It is a diagram showing an example of pairing data for a relay device. [Figure 7] It is a diagram showing an example of pairing data for a sensor terminal. [Figure 8] It is a diagram for explaining the first embodiment. [Figure 9] It is a diagram showing a configuration example of a route management unit. [Figure 10] It is a diagram showing an example of a procedure of a management method. [Figure 11] It is a diagram for explaining the change of pairing data. [Figure 12] It is a diagram for explaining the change of pairing data. [Figure 13] It is a diagram for explaining the second embodiment. [Figure 14] [[ID=四十七]]It is a diagram showing a configuration example of a transmission management unit. [Figure 15] This is a diagram showing an example of a database. [Figure 16] This is a diagram showing an example of a time table. [Figure 17] This is a diagram showing an example of the procedure of a management method. [Figure 18] This is a diagram for explaining the third embodiment. [Figure 19] This is a diagram showing an example of the configuration of a frequency management unit. [Figure 20] This is a diagram showing an example of the procedure of a management method. [Figure 21] This is a diagram showing an example of the procedure of a management method. [Figure 22] This is a diagram showing an example of the procedure of a management method.

Modes for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0019] [System Overview] FIG. 1 is a block diagram showing a configuration example of a wireless communication system 100. The wireless communication system 100 includes an access point 1, one or more relay devices 2, and a plurality of sensor terminals 3. The wireless communication system 100 may further include a server 4.

[0020] The access point 1 and the server 4 are connected to a communication network such as a wired LAN or the Internet. The access point 1 is an example of a higher-level wireless device. Not limited to this, the higher-level wireless device may be, for example, a router or the like.

[0021] The relay device 2 relays wireless communication between the access point 1 and the sensor terminal 3. The sensor terminal 3 is a wireless communication terminal equipped with a sensor, and transmits sensor data detected by the sensor. The sensor terminal 3 is a so-called IoT device.

[0022] The sensor terminal 3 can be any of the following types of sensors: a light sensor, an image sensor, a pressure sensor, a temperature sensor, a humidity sensor, or an acceleration sensor.

[0023] Access point 1, relay device 2, and sensor terminal 3 are capable of wireless communication using the 920MHz band. Specifically, access point 1, relay device 2, and sensor terminal 3 are capable of wireless communication using, for example, the IEEE standard 802.11ah.

[0024] The 920MHz band is suitable for long-distance communication, and furthermore, by having a relay device 2 interposed between the access point 1 and the sensor terminal 3, the wireless communication system 100 can collect sensor data from a large number of sensor terminals 3 located over a wide area.

[0025] However, in the 920MHz band, the Radio Law limits the transmission time per unit time (also called transmission duty cycle) to 10%. Specifically, the transmission time is limited to within 6 minutes per hour.

[0026] Each sensor terminal 3 transmits sensor data via a route that reaches the access point 1 via a relay device 2 (hereinafter also referred to as the "upstream route"). That is, along the upstream route, sensor data is transmitted from the sensor terminal 3 to the relay device 2, and then from the relay device 2 to the access point 1.

[0027] Furthermore, access point 1 transmits management data to sensor terminal 3 via a route opposite to the uplink route (hereinafter also referred to as the "downlink route"). Specifically, on the downlink route, the management data is transmitted from access point 1 to relay device 2, and then from relay device 2 to sensor terminal 3.

[0028] Figure 2 is a block diagram showing an example configuration of access point 1. Access point 1 comprises a control unit 10, a wireless communication unit 11, and a wired communication unit 12.

[0029] The control unit 10 is a computer that includes a CPU, RAM, ROM, non-volatile memory, and input / output interfaces. The CPU of the control unit 10 performs information processing according to a program loaded from ROM or non-volatile memory into RAM.

[0030] The program may be supplied via an information storage medium such as an optical disc or memory card, or via a communication network such as the Internet or LAN.

[0031] The wireless communication unit 11 enables wireless communication using the 920MHz band. The wired communication unit 12 is connected to a wired LAN. The control unit 10 bridges the wireless communication terminal connected to the wireless communication unit 11 and the wired LAN connected to the wired communication unit 12.

[0032] Figure 3 is a block diagram showing an example configuration of the relay device 2. The relay device 2 comprises a control unit 20 and a wireless communication unit 21. The control unit 20 and the wireless communication unit 21 have the same configuration as the control unit 10 and the wireless communication unit 11 of the access point 1.

[0033] Figure 4 is a block diagram showing an example configuration of the sensor terminal 3. The sensor terminal 3 comprises a control unit 30, a wireless communication unit 31, and a sensor 33. The control unit 30 and the wireless communication unit 31 have the same configuration as the control unit 10 and the wireless communication unit 11 of the access point 1.

[0034] The control unit 10 generates sensor data based on the electrical signals output from the sensor 33. The control unit 10 also performs configuration changes and other operations based on the received management data. Note that the sensor terminal 3 is not limited to one sensor 33; it may have multiple sensors.

[0035] Figures 5 through 7 show examples of pairing data. Each of the access point 1, relay device 2, and sensor terminal 3 holds pairing data to define the route on which sensor data or management data is transmitted. The route defined in the pairing data includes both uplink and downlink routes. The pairing data is defined by the identifiers of the access point 1, relay device 2, and sensor terminal 3 along the route.

[0036] As shown in the example in Figure 5, the pairing data for access point 1 includes route data that originates from or terminates at access point 1. When access point 1 receives management data from server 4, it refers to the pairing data and identifies the relay device 2 to which the management data will be sent. For example, access point "AP" sends management data to relay device "RP1" which is included in route 1 for sending management data to sensor terminal "ST1".

[0037] As shown in the example in Figure 6, the pairing data for the relay device 2 includes the route data that passes through the relay device 2. When the relay device 2 receives management data from the access point 1, it refers to the pairing data and identifies the sensor terminal 3 to which the management data will be sent. For example, the relay device "RP1" sends the management data to the sensor terminal "ST1" which is included in route 1 for sending the management data.

[0038] Furthermore, when the relay device 2 receives sensor data from the sensor terminal 3, it refers to the pairing data to identify the access point 1 to which the sensor data will be sent. For example, the relay device "RP1" sends the sensor data to the access point "AP" included in route 1 for sending sensor data from the sensor terminal "ST1".

[0039] As shown in the example in Figure 7, the pairing data for sensor terminal 3 includes route data originating from or ending at sensor terminal 3. Sensor terminal 3 refers to the pairing data to identify the relay device 2 to which the sensor data will be transmitted. For example, sensor terminal "ST1" transmits sensor data to relay device "RP1" which is included in route 1 for transmitting sensor data.

[0040] [First Embodiment] Figure 8 is a diagram illustrating the first embodiment. In this embodiment, the wireless communication system 100 includes a plurality of relay devices 2a, 2b. In this embodiment, a route management unit 5 is installed at each of the plurality of sensor terminals 3. The route management unit 5 is an example of a management device. In the figure, only one sensor terminal 3 is shown for illustrative purposes, but the number of sensor terminals 3 is greater than the number of relay devices 2.

[0041] The route management unit 5 is not limited to the sensor terminal 3; for example, it may be installed in the relay device 2, the access point 1, the server 4, or as an independent device.

[0042] When one sensor terminal 3 can communicate with two relay devices 2a and 2b, there are two possible routes for the sensor terminal 3 to transmit sensor data and receive management data: route Ra, which goes through relay device 2a, and route Rb, which goes through relay device 2b. Here, we assume that route Ra is used first.

[0043] Route Ra includes an uplink route in which sensor data is transmitted from sensor terminal 3 to relay device 2a and then from relay device 2a to access point 1. Route Ra also includes a downlink route in which management data is transmitted from access point 1 to relay device 2a and then from relay device 2a to sensor terminal 3.

[0044] Route Rb includes an uplink route in which sensor data is transmitted from sensor terminal 3 to relay device 2b, and then from relay device 2b to access point 1. Route Rb also includes a downlink route in which management data is transmitted from access point 1 to relay device 2b, and then from relay device 2b to sensor terminal 3.

[0045] Incidentally, in a system like the wireless communication system 100, where sensor data from sensor terminals 3 is transmitted to access point 1 via relay device 2, the transmission time of relay device 2 tends to increase compared to that of sensor terminals 3 or access point 1 because data is concentrated in relay device 2. This problem becomes more pronounced as the number of sensor terminals 3 increases.

[0046] Therefore, in this embodiment, excessive use of the relay device 2 is suppressed by changing the route according to the usage history of the relay device 2, as described below.

[0047] Figure 9 is a block diagram showing an example configuration of the route management unit 5. The route management unit 5 is implemented by the CPU of the sensor terminal 3 executing information processing according to a program. The route management unit 5 includes a transmission time acquisition unit 51 and a route change unit 52.

[0048] The transmission time acquisition unit 51 acquires the transmission time per unit time from the relay devices 2a and 2b. The relay devices 2a and 2b measure the transmission time per hour, and the transmission time acquisition unit 51 periodically acquires the current value of the transmission time per hour from the relay devices 2a and 2b. The transmission time per hour may be, for example, the transmission time in each hourly time frame, or the transmission time in the most recent hour.

[0049] The route change unit 52 changes the route to route Rb via another relay device 2b if the transmission time of the relay device 2a included in the currently used route Ra exceeds a threshold. That is, based on the transmission time acquired by the transmission time acquisition unit 51, the route change unit 52 changes the route to another route Rb via a relay device 2b whose transmission time is less than the threshold if the transmission time of the relay device 2a included in the currently used route Ra exceeds a threshold. The threshold is set, for example, to 8% of the transmission time per unit time, with a margin of 10%. The threshold and the destination relay device 2b may be determined based on the amount of data to be transmitted by the sensor terminal, the distance between the sensor terminal and the relay device, the transmission waiting time of the sensor terminal, the time of day, the weather, the wireless communication conditions including the number of communication errors, and the number of times the threshold has been reached in a certain period in the past.

[0050] The route change unit 52 sends a route change request to the access point 1, relay devices 2a and 2b, and sensor terminal 3 to change from route Ra to route Rb. Upon receiving the route change request, the access point 1, relay devices 2a and 2b, and sensor terminal 3 update their pairing data to change from route Ra to route Rb.

[0051] Figure 10 is a flowchart showing an example of a procedure for managing the wireless communication system 100 according to the first embodiment. The CPU of the sensor terminal 3 functions as a route management unit 5 by executing the information processing shown in the figure according to the program.

[0052] The relay devices 2a and 2b transmit the current transmission time (S21, S31). The relay devices 2a and 2b may periodically transmit the current transmission time by, for example, including it in a beacon, or they may transmit the current transmission time in response to a periodic request from the route management unit 5.

[0053] The route management unit 5 obtains the current transmission time from the relay devices 2a and 2b (S11, processing as the transmission time acquisition unit 51).

[0054] The route management unit 5 monitors the transmission time of the relay device 2a included in the currently used route Ra, and if the transmission time of the relay device 2a exceeds a threshold (S12: YES), it executes a route change process (S13 to S15, processing as the route change unit 52).

[0055] The threshold is preferably set to be smaller than the transmission time limit per unit time (specifically, 6 minutes per hour).

[0056] In the route change process, the route management unit 5 confirms that the transmission time of the other relay device 2b is below a threshold (S13: YES), updates the pairing data held by the sensor terminal 3 (S14), and sends a route change request to the relay devices 2a and 2b (S15).

[0057] If there are multiple other relay devices 2b, the route management unit 5 selects the relay device 2b with the shortest transmission time from among the multiple relay devices 2b. Alternatively, the route management unit 5 may select the relay device 2b with the strongest signal strength from among the multiple relay devices 2b.

[0058] The acquisition of the transmission time from other relay devices 2b in S11 may be performed when confirming in S13 that the transmission time of other relay devices 2b is below a threshold.

[0059] In the S14 pairing data update, the "relay device" portion of the pairing data (see Figure 7), which is the destination for the sensor data, is changed from relay device 2a to relay device 2b.

[0060] When relay devices 2a and 2b receive a route change request (S22, S32: YES), they update the pairing data (S23, S33).

[0061] Specifically, the relay device 2a discards the pairing data representing route Ra in response to a route change request. For example, as shown in Figure 11, the pairing data of the relay device 2a discards the data of the sensor terminal 3 (referred to here as "ST3") that sent the route change request.

[0062] Furthermore, the relay device 2b generates pairing data representing route Rb in response to a route change request. For example, as shown in Figure 12, the pairing data of the relay device 2b newly generates data for the sensor terminal 3 (referred to here as "ST3") that sent the route change request.

[0063] Similarly, the route management unit 5 also sends a route change request to the access point 1. Upon receiving the route change request, the access point 1 discards the pairing data representing route Ra and generates pairing data representing route Rb in its pairing data (see Figure 5).

[0064] As a result of the above processing, the route used is changed from route Ra to route Rb, and consequently, sensor data from sensor terminal 3 is transmitted to access point 1 via relay device 2b. In addition, management data from access point 1 is also transmitted to sensor terminal 3 via relay device 2b.

[0065] According to this embodiment, if the transmission time of relay device 2a included in the currently used route Ra exceeds a threshold, the system is changed to use another route Rb that passes through relay device 2b whose transmission time is less than the threshold. This makes it possible to prevent the transmission time of relay device 2a from exceeding the limit.

[0066] [Second Embodiment] Figure 13 is a diagram illustrating a second embodiment. In this embodiment, a transmission management unit 6 is installed on the server 4. The transmission management unit 6 is an example of a management device. In this figure, only one relay device 2 is shown for the sake of clarity, but there may be multiple relay devices 2.

[0067] The server 4 of the transmission management unit 6 is not limited to a server 4 on the network, but may also be installed at, for example, an access point 1, a relay device 2, a sensor terminal 3, or as an independent device.

[0068] By the way, in a system like the wireless communication system 100, where sensor data from sensor terminals 3 is transmitted to access point 1 via relay device 2, if the timing of sensor data transmission from multiple sensor terminals 3 is concentrated, the transmission time of relay device 2 may exceed its limit.

[0069] Therefore, in this embodiment, the transmission timing of sensor data from multiple sensor terminals 3 is managed as described below.

[0070] Figure 14 is a block diagram showing an example configuration of the transmission management unit 6. The transmission management unit 6 is implemented by the CPU of the server 4 executing information processing according to a program. The transmission management unit 6 includes a determination unit 61 and a setting unit 62.

[0071] The determination unit 61 predetermines the transmission timing at which multiple sensor terminals 3 will transmit sensor data. The setting unit 62 sets the transmission timing determined by the determination unit 61 to the multiple sensor terminals 3.

[0072] The determination unit 61 refers to a database (see Figure 15) in which data related to the sensor data is stored, and determines the transmission timing at which multiple sensor terminals 3 will transmit sensor data.

[0073] As shown in Figure 15, the database includes fields such as "Sensor Terminal," "Sensor Data," "Data Volume," and "Transmission Period." "Sensor Terminal" represents the identifier of sensor terminal 3.

[0074] "Sensor data" refers to the sensor data transmitted by the sensor terminal 3. If a single sensor terminal 3 is equipped with multiple sensors 33, multiple sets of sensor data are associated with that sensor terminal 3.

[0075] "Data volume" refers to the amount of sensor data. The data volume does not need to be an exact value; for example, it could be an estimate or a grade of data volume. "Transmission cycle" refers to the transmission cycle of the sensor data.

[0076] The determination unit 61 allocates the transmission timing of sensor data to predetermined time slots (specifically, 1 hour) in the timetable (see Figure 16). Here, the predetermined time slots are divided into units of time in the 920MHz band where the transmission time per unit is limited.

[0077] At this time, the decision unit 61 distributes the transmission timing by allocating the transmission timing of some sensor terminals 3 to a first time frame and allocating the transmission timing of other sensor terminals 3 to a second time frame separate from the first time frame. For example, as shown in Figure 16, the sensor data D1, D2, and D4 from sensor terminals ST1, ST2, and ST4 are allocated to the 14:00 time frame, and the sensor data D31 and D32 from sensor terminal ST3 are allocated to the 15:00 time frame.

[0078] Furthermore, the decision unit 61 allocates the transmission timing of sensor data to time slots, taking into account the transmission cycle of sensor data stored in the database (see Figure 15). For example, if the transmission cycles T1 and T2 of sensor data D1 and D2 are 2 hours, then if sensor data D1 and D2 are allocated to the 14:00 and 16:00 time slots, other sensor data D31 and D32 will avoid 14:00 and 16:00 and be allocated to the 15:00 time slot.

[0079] Furthermore, the determination unit 61 limits the number of sensor data transmission timings allocated to a single time frame to a predetermined number or less. For example, when the number of sensor data transmission timings allocated to a single time frame is limited to three or less, if three sensor data D1, D2, and D4 are allocated to the 14:00 time frame, the other sensor data D31 and D32 will be allocated to the 15:00 time frame.

[0080] Furthermore, the decision unit 61 allocates the timing of sensor data transmission to time slots according to the amount of sensor data stored in the database (see Figure 15). For example, if the sum of the data amounts A1, A2, A4 for sensor data D1, D2, and D4 is close to the amount of data for one hour, then if sensor data D1, D2, and D4 are allocated to the 14:00 time slot, the other sensor data D31 and D32 will be allocated to the 15:00 time slot.

[0081] According to this embodiment, by distributing the transmission timing of sensor data from multiple sensor terminals 3, it is possible to prevent the transmission time of the relay device 2, which relays the sensor data, from exceeding the limit.

[0082] Figure 17 is a flowchart showing an example of a procedure for managing the wireless communication system 100 according to the second embodiment. The CPU of the server 4 functions as a transmission management unit 6 by executing the information processing shown in the figure according to the program.

[0083] The following describes an example of the process for determining the timing of sensor data transmission when a new sensor terminal 3 is added, or when a new sensor 33 is added to any of the sensor terminals 3. However, the timing of sensor data transmission may be determined simultaneously.

[0084] When sensor terminal 3 detects an addition (S51: YES), it notifies transmission management unit 6 of the addition (S52). In other words, sensor terminal 3 notifies transmission management unit 6 of the addition when the unit is installed or when a new sensor 33 is added to the unit.

[0085] When the transmission management unit 6 receives notification of an expansion from the sensor terminal 3 (S41: YES), it determines the transmission timing at which the sensor terminal 3 will transmit sensor data (S42, processing as the determination unit 61), and notifies the sensor terminal 3 of the determined transmission timing (S43, processing as the setting unit).

[0086] As described above, the timing of transmission is determined by considering the timing of sensor data transmission by other sensor terminals 3 in the timetable (see Figure 16). In other words, the timing of transmission of new sensor data is determined so that the transmission timings of multiple sensor data are not concentrated in a specific time frame but are distributed.

[0087] When the sensor terminal 3 receives notification of the transmission timing from the transmission management unit 6 (S51: YES), it sets the notified transmission timing (S52). Thereafter, when the set transmission timing arrives, the sensor terminal 3 transmits the sensor data to the relay device 2.

[0088] According to this, when a new sensor terminal 3 is added, or when a new sensor 33 is added to any of the sensor terminals 3, it becomes possible to determine the timing of the transmission of new sensor data so as not to coincide with the timing of the transmission of sensor data by other sensor terminals 3.

[0089] [Third Embodiment] Figure 18 is a diagram illustrating a third embodiment. In this embodiment, a frequency management unit 7 is installed on the server 4. The frequency management unit 7 is an example of a management device. In this figure, only one relay device 2 is shown for the sake of clarity, but there may be multiple relay devices 2.

[0090] The frequency management unit 7 is not limited to the server 4; for example, it may be installed on the access point 1, the relay device 2, the sensor terminal 3, or as an independent device.

[0091] By the way, in a system like the wireless communication system 100, where sensor data from a sensor terminal 3 is transmitted to an access point 1 via a relay device 2, the frequency of sensor data transmission may fluctuate depending on the urgency, etc. If the transmission frequency increases excessively, the transmission time of the relay device 2 may exceed its limit.

[0092] Therefore, in this embodiment, excessive use of the relay device 2 is suppressed by balancing the transmission frequency of sensor data, as described below.

[0093] Figure 19 is a block diagram showing an example configuration of the frequency management unit 7. The frequency management unit 7 is realized by the CPU of the server 4 performing information processing. The frequency management unit 7 includes a monitoring unit 71 and a modification unit 72.

[0094] The monitoring unit 71 monitors the transmission frequency of sensor data from multiple sensor terminals 3. The modification unit 72 decreases the transmission frequency of sensor data from other sensor terminals 3 (hereinafter referred to as "sensor terminal 3b") when the transmission frequency of sensor data from one of the multiple sensor terminals 3 (hereinafter referred to as "sensor terminal 3a") increases.

[0095] The monitoring unit 71 may detect an increase in the frequency of sensor data transmission from the sensor terminal 3a when the frequency of sensor data transmission exceeds a threshold, when the rate of change of the frequency of sensor data transmission exceeds a threshold, or when the derivative of the frequency of sensor data transmission exceeds a threshold.

[0096] Furthermore, the monitoring unit 71 may detect an increase in the frequency of sensor data transmission from the sensor terminal 3a when it receives notification from the sensor terminal 3a that the frequency of sensor data transmission has increased. In addition, the monitoring unit 71 may determine the urgency based on the sensor data from multiple sensor terminals 3.

[0097] The modification unit 72 instructs the sensor terminal 3b to reduce the frequency of sensor data transmission. When the sensor terminal 3b receives an instruction from the frequency management unit 7 to reduce the transmission frequency, it reduces the frequency of sensor data transmission. The modification unit 72 may also stop the transmission of sensor data by the sensor terminal 3b.

[0098] Figures 20 to 22 are flowcharts showing an example procedure for managing the wireless communication system 100 according to the third embodiment. The CPU of the server 4 functions as the frequency management unit 7 by executing the information processing shown in the figures according to the program. For overlapping steps, the same number is used to omit detailed explanations.

[0099] Figure 20 is a flowchart of the first example. Sensor terminal 3a determines the degree of urgency based on sensor data (S71), and if an emergency is detected, i.e., if the degree of urgency is above a predetermined level (S72: YES), it increases the frequency of transmission of sensor data (S73).

[0100] The sensor terminal 3a periodically performs this urgency determination. The urgency is the level of urgency of the object being monitored by the sensor 33, and is expressed, for example, in classes according to the magnitude of the sensor data values.

[0101] The frequency management unit 7 monitors the frequency of sensor data transmission (S61, processing as the monitoring unit 71), and when it detects an increase in the frequency of sensor data transmission by the sensor terminal 3a (S62: YES), it determines which sensor terminal 3b will reduce the transmission frequency (S63) and instructs the sensor terminal 3b to reduce the transmission frequency (S64: processing as the modification unit 72).

[0102] If there are multiple sensor terminals 3 other than sensor terminal 3a, the frequency management unit 7 determines, for example, the sensor terminal 3 with the lowest urgency level, determined based on sensor data, to be the sensor terminal 3b whose transmission frequency will be reduced.

[0103] When the sensor terminal 3b receives an instruction from the frequency management unit 7 to reduce the transmission frequency (S81: YES), it reduces the transmission frequency of sensor data (S82).

[0104] Figure 21 is a flowchart of the second example. Sensor terminal 3a determines the urgency level based on sensor data (S71), and if an emergency condition is detected (S72: YES), it increases the frequency of sensor data transmission (S73) and sends a notification of the increased transmission frequency to frequency management unit 7 (S74). The notification of increased transmission frequency is also a notification of an emergency condition.

[0105] When the frequency management unit 7 receives notification of an increase in transmission frequency (S65:YES), it determines which sensor terminal 3b will have its transmission frequency reduced (S63) and instructs the sensor terminal 3b to reduce its transmission frequency (S64). When the sensor terminal 3b receives an instruction from the frequency management unit 7 to reduce its transmission frequency (S81:YES), it reduces the transmission frequency of sensor data (S82).

[0106] Figure 22 is a flowchart of the third example. The frequency management unit 7 monitors the sensor data of multiple sensor terminals 3 and determines, based on that sensor data, whether any of the sensor terminals 3 are in an emergency state, that is, whether the degree of urgency is above a predetermined level (S66 to S67, processing as the monitoring unit 71).

[0107] When the frequency management unit 7 detects a sensor terminal 3a with an urgency level above a predetermined level (S67:YES), it notifies the sensor terminal 3a of the emergency status (S68). The notification of the emergency status also serves as an instruction to increase the transmission frequency. When the sensor terminal 3a receives the notification of the emergency status from the frequency management unit 7 (S75:YES), it increases the transmission frequency of sensor data (S73).

[0108] Furthermore, the frequency management unit 7 determines that the sensor terminal 3b with low urgency is the target for reducing the transmission frequency (S63), and instructs the sensor terminal 3b to reduce the transmission frequency (S64). When the sensor terminal 3b receives the instruction from the frequency management unit 7 to reduce the transmission frequency (S81: YES), it reduces the transmission frequency of sensor data (S82).

[0109] According to this embodiment, when the transmission frequency of sensor data from sensor terminal 3a increases, the transmission frequency of sensor data from sensor terminal 3b is reduced, thereby preventing the transmission time of the relay device 2, which relays the sensor data, from exceeding its limit. Furthermore, it is possible to avoid a situation where sensor terminal 3a, which is in an emergency state, is unable to transmit sensor data.

[0110] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are, of course, possible for those skilled in the art. Furthermore, the multiple embodiments described above can be combined as appropriate.

[0111] The following lists representative embodiments of the present invention.

[0112] (1) A higher-level communication device receives sensor data via 802.11ah wireless communication, A relay device that relays the sensor data to the higher-level communication device via 802.11ah wireless communication, Multiple sensor terminals transmit the sensor data to the relay device via 802.11ah wireless communication. A server having a frequency management unit that reduces the frequency of transmission of sensor data from other sensor terminals when the transmission frequency of sensor data from one of the plurality of sensor terminals increases, A wireless communication system equipped with the following features.

[0113] (2) The frequency management unit stops the transmission of the sensor data from the other sensor terminal. (1) The wireless communication system described above.

[0114] (3) The frequency management unit monitors the transmission frequency of the sensor data from the multiple sensor terminals, and when the transmission frequency of the sensor data from one sensor terminal increases, it reduces the transmission frequency of the sensor data from the other sensor terminals. The wireless communication system described in (1) or (2).

[0115] (4) When the frequency management unit receives notification from one sensor terminal that the transmission frequency of the sensor data has increased, it reduces the transmission frequency of the sensor data from other sensor terminals. The wireless communication system described in (1) or (2).

[0116] (5) The aforementioned plurality of sensor terminals increase the frequency of transmission of the sensor data when an emergency condition is detected. A wireless communication system as described in any of (1) through (4).

[0117] (6) The frequency management unit determines the degree of urgency based on the sensor data from the plurality of sensor terminals and notifies the sensor terminals with a degree of urgency equal to or greater than a predetermined level of emergency. (5) The wireless communication system described above.

[0118] (7) The aforementioned plurality of sensor terminals determine the degree of urgency based on the sensor data and detect an emergency state if the degree of urgency is above a predetermined level. (5) The wireless communication system described above.

[0119] (8) The frequency management unit, when the transmission frequency of sensor data from one sensor terminal increases, reduces the transmission frequency of sensor data from sensor terminals whose urgency is determined to be low based on the sensor data. A wireless communication system as described in any of (1) through (7).

[0120] (9) In a wireless communication system comprising a higher-level communication device that receives sensor data via 802.11ah wireless communication, a relay device that relays the sensor data to the higher-level communication device via 802.11ah wireless communication, and a plurality of sensor terminals that transmit the sensor data to the relay device via 802.11ah wireless communication, the system reduces the transmission frequency of sensor data of the other sensor terminals when the transmission frequency of sensor data of one of the plurality of sensor terminals increases. Methods for managing wireless communication systems.

[0121] (10) A wireless communication system comprising: a higher-level communication device that receives sensor data via 802.11ah wireless communication; a relay device that relays the sensor data to the higher-level communication device via 802.11ah wireless communication; and a plurality of sensor terminals that transmit the sensor data to the relay device via 802.11ah wireless communication, wherein a modification unit reduces the transmission frequency of sensor data of the other sensor terminals when the transmission frequency of sensor data of one of the plurality of sensor terminals increases. A control device equipped with the following features. [Explanation of Symbols]

[0122] 1 Access point (example of higher-level communication device), 2 Relay device, 3 Sensor terminal, 4 Server, 5 Route management unit, 6 Transmission management unit, 7 Frequency management unit, 10 Control unit, 11 Wireless communication unit, 12 Wired communication unit, 20 Control unit, 21 Wireless communication unit, 30 Control unit, 31 Wireless communication unit, 33 Sensor, 51 Transmission time acquisition unit, 52 Route change unit, 61 Determination unit, 62 Setting unit, 71 Monitoring unit, 72 Change unit

Claims

1. A higher-level communication device receives sensor data via 802.11ah wireless communication, A relay device that relays the sensor data to the higher-level communication device via 802.11ah wireless communication, Multiple sensor terminals transmit the sensor data to the relay device via 802.11ah wireless communication, A server having a frequency management unit that reduces the frequency of transmission of sensor data from other sensor terminals when the transmission frequency of sensor data from one of the plurality of sensor terminals increases, A wireless communication system equipped with the following features.

2. The frequency management unit stops the transmission of the sensor data from the other sensor terminal. The wireless communication system according to claim 1.

3. The frequency management unit monitors the transmission frequency of the sensor data from the multiple sensor terminals, and when the transmission frequency of the sensor data from one sensor terminal increases, it reduces the transmission frequency of the sensor data from the other sensor terminals. The wireless communication system according to claim 1.

4. When the frequency management unit receives notification from one sensor terminal that the transmission frequency of the sensor data has increased, it reduces the transmission frequency of the sensor data from other sensor terminals. The wireless communication system according to claim 1.

5. The aforementioned plurality of sensor terminals increase the frequency of transmission of the sensor data when an emergency condition is detected. The wireless communication system according to claim 1.

6. The frequency management unit determines the degree of urgency based on the sensor data from the plurality of sensor terminals and notifies the sensor terminals with a degree of urgency equal to or greater than a predetermined level of emergency. The wireless communication system according to claim 5.

7. The aforementioned plurality of sensor terminals determine the degree of urgency based on the sensor data and detect an emergency state if the degree of urgency is above a predetermined level. The wireless communication system according to claim 5.

8. The frequency management unit, when the transmission frequency of sensor data from one sensor terminal increases, reduces the transmission frequency of sensor data from sensor terminals whose urgency is determined to be low based on the sensor data. The wireless communication system according to claim 1.

9. In a wireless communication system comprising a higher-level communication device that receives sensor data via 802.11ah wireless communication, a relay device that relays the sensor data to the higher-level communication device via 802.11ah wireless communication, and a plurality of sensor terminals that transmit the sensor data to the relay device via 802.11ah wireless communication, the system reduces the transmission frequency of sensor data of the other sensor terminals when the transmission frequency of sensor data of one of the plurality of sensor terminals increases. Methods for managing wireless communication systems.

10. A wireless communication system comprising: a higher-level communication device that receives sensor data via 802.11ah wireless communication; a relay device that relays the sensor data to the higher-level communication device via 802.11ah wireless communication; and a plurality of sensor terminals that transmit the sensor data to the relay device via 802.11ah wireless communication, wherein a modification unit reduces the transmission frequency of sensor data of the other sensor terminals when the transmission frequency of sensor data of one of the plurality of sensor terminals increases. A control device equipped with the following features.

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