JP7243244B2 - Communication system, gateway device, relay processing program, communication control device, communication control program and communication method - Google Patents

Description

The present invention relates to a communication system, a gateway device, a relay processing program, a communication control device, a communication control program and a communication method. For example, it can be applied to a system that communicates with a host device (eg, an application server) via a network server, etc.).

Conventionally, there is LoRa (LoRaWAN) as a wireless communication scheme that covers a wide area with low power consumption (Non-Patent Document 1).

In a conventional communication system to which LoRa (Specification v1.0.3) shown in Non-Patent Document 1 is applied, a child device (hereinafter also referred to as "EndDevice") that performs wireless communication is connected to a host device via a GW and a network server. (for example, an application server) for wireless communication. At this time, the EndDevice is not aware that it is connected to a specific GW.

Here, uplink data communication (uplink data communication) in a communication system to which LoRa (Non-Patent Document 1) is applied will be described. The upstream data transmitted by the EndDevice is received by a plurality of GWs that receive radio waves, and the GWs transmit the data to the network server. The network server receives the same upstream data from a plurality of GWs, but validates the upstream data from the GW that received the strongest radio wave intensity from the EndDevice and transfers it to the application server. At that time, the network server discards the upstream data received from other GWs.

Next, downlink data communication (downlink data communication) in a communication system to which LoRa (Non-Patent Document 1) is applied will be described. In the LoRa protocol shown in Non-Patent Document 1, an intermittent downlink mechanism called Class B is standardized for the purpose of power saving of EndDevice. Hereinafter, this downlink communication scheme is also referred to as "LoRa Class B communication".

Specifically, in LoRa Class B communication, when downstream data is generated from the application server, the network server transmits the data via the GW that received the strongest radio wave intensity from the destination EndDevice immediately before. . The GW then transmits synchronization signals called Beacons at intervals of 128 seconds. In the LoRa protocol, this Beacon and Beacon are divided into 4096 slots every 30 ms. Then, the EndDevice calculates the slot assigned to itself among the 4096 slots by a certain algorithm, and sets the wireless reception mode at the timing of the slot (hereafter, this slot is called "PingSlot"). Since the EndDevice turns off the radio except for the PingSlot assigned to itself, it is possible to save power. When the GW receives downstream data from the network server, it temporarily caches the data and then transmits the data to the PingSlot of the destination EndDevice.

"LoRaWAN (TM) Specification v1.0.3", LoRa Alliance (TM), INTERNET, [searched January 21, 2019], <https://lora-alliance.org/resource-hub/lorawantm-specification- v103>

In conventional LoRa Class B communication, as described above, a beacon signal is used by EndDevice and GW to measure the timing of downlink data. However, in conventional LoRa Class B communication, EndDevice communicates without being aware of multiple GWs, so Beacons transmitted by multiple GWs must be transmitted from multiple GWs at the same timing. This is because when the EndDevice receives Beacon signals that are transmitted from a plurality of GWs at different times, radio wave interference occurs and the Beacon signals are mutually crushed, and the EndDevice cannot correctly recognize the Beacon signal.

Therefore, in conventional LoRa Class B communication, a plurality of GWs use GPS time included in GPS radio waves in order to synchronize the transmission timing of Beacon signals. However, since GPS radio waves can only be received outdoors with good visibility, there is a problem that LoRa Class B communication cannot be used in GWs installed in underground malls or indoors. That is, in conventional LoRa Class B communication, there is a problem that downstream data may not be transmitted to EndDevice using a GW installed in a place where GPS radio waves cannot be received.

In view of the above problems, data transmission (transmission of downlink data) using a downlink signal to a child device (EndDevice) via a gateway device (GW) that cannot receive radio waves for time synchronization (for example, GPS radio waves) A communication system, a gateway device, a relay processing program, a communication control device, a communication control program, and a communication method are desired.

A first aspect of the present invention comprises a child device, one or more gateway devices connected to the child device by wireless communication, relaying communication between each of the gateway devices and a host device, and each of the gateway devices each of the gateway devices includes (1) time synchronization signal receiving means for receiving a time synchronization signal from the outside of the gateway device; and (2) the child device (3) a second communication unit capable of communicating with the communication control device; and (4) a beacon signal to the child device via the first communication unit and (5) determining the timing at which the beacon transmission processing means transmits the beacon signal, and transmitting the beacon signal to the beacon transmission processing means at the determined timing. (6) after a predetermined time has elapsed from the timing at which the beacon transmission processing means transmits the beacon signal, the first communication unit is used to transmit a downlink signal addressed to the child device. (7) when the first communication unit receives an uplink signal from the child device, the uplink signal is transferred from the second communication unit to the communication control device; (8) clock means for keeping time in said gateway device; ( 9 ) said timing control means, when said time synchronization signal receiving means receives said time synchronization signal and controlling at a first beacon transmission timing in which the timing interval is a constant period, and if the time synchronization signal receiving means does not receive the time synchronization signal, the first beacon transmission timing is delayed by a predetermined delay time. A communication system characterized in that control is performed at the second beacon transmission timing determined by the second beacon transmission timing.

In a second aspect of the present invention, a child device, one or a plurality of gateway devices connected to the child device by wireless communication, relaying communication between each of the gateway devices and the host device, and each of the gateway devices (1) time synchronization signal receiving means for receiving a time synchronization signal from the outside of the gateway device; (2) the slave unit; (3) a second communication unit capable of communicating with the communication control device; and (4) the beacon signal to the child device via the first communication unit. and (5) determining the timing at which the beacon transmission processing means transmits the beacon signal, and transmitting the beacon signal to the beacon transmission processing means at the determined timing. (6) after a predetermined time has elapsed from the timing at which the beacon transmission processing means transmits the beacon signal, the first communication unit is used to transmit a downlink signal addressed to the child device. (7) when the first communication unit receives an uplink signal from the child device, the uplink signal is transferred from the second communication unit to the communication control device; (8) clock means for keeping time in said gateway device; ( 9 ) said timing control means, when said time synchronization signal receiving means receives said time synchronization signal and controlling at a first beacon transmission timing in which the timing interval is a constant period, and if the time synchronization signal receiving means does not receive the time synchronization signal, the first beacon transmission timing is delayed by a predetermined delay time. A gateway device characterized in that the gateway device is controlled at the second beacon transmission timing determined.

A relay processing program according to a third aspect of the present invention comprises: a child device; one or more gateway devices connected to the child device by wireless communication; and a communication control device for controlling communication of the gateway device, comprising a time synchronization signal receiving means for receiving a time synchronization signal from the outside of the gateway device; and a second communication unit capable of communicating with the communication control device. (2) determining a timing for the beacon transmission processing means to transmit the beacon signal, and transmitting the beacon transmission processing means to the beacon transmission processing means at the determined timing; (3) after a predetermined time elapses from the timing at which the beacon transmission processing means transmits the beacon signal, using the first communication unit, the child device is set as a destination; (4) when the first communication unit receives an uplink signal from the child device, the uplink signal is transmitted from the second communication unit to the communication unit; (5) functioning as clock means for measuring the time in the gateway device; When the signal is received, control is performed at the first beacon transmission timing having a constant interval between the timings, and when the time synchronization signal receiving means does not receive the time synchronization signal, the first beacon transmission timing is set to the predetermined timing. A relay processing program characterized by controlling at a second beacon transmission timing delayed by a delay time.

A communication control device according to a fourth aspect of the present invention comprises a child device, one or more gateway devices connected to the child device by wireless communication, relaying communication between each gateway device and a host device, and and a communication control device for controlling communication of the gateway device, wherein: (1) an uplink signal received from the gateway device and destined for the host device is transferred to the host device; wherein, when the upstream signal transmitted from the child device is received via a plurality of the gateway devices, the upstream signal to which the strongest radio wave intensity information is added is transferred to the host device. (2) downstream signal transfer processing means for selecting one of the gateway devices when a downstream signal is received from the higher-level device and transferring the downstream signal to the selected gateway device; (3) When receiving uplink signals including control signals sent by the slave unit at the time of connection from a plurality of gateway devices, to the gateway device that relays the uplink signal to which the strongest radio wave intensity information is added, (4) control signal processing means for performing processing for transmitting a downlink signal including a control signal responding to the child device; (5) first storage means for storing first information associated with the gateway device that transmitted the signal; (6) each of: (7) said downlink signal transfer processing means; and when a downlink signal addressed to the child device is received from the host device, the operation mode of the gateway device indicated by the first information corresponding to the child device and the gateway device indicated by the second information. either the gateway device indicated by the first information corresponding to the child device or the gateway device indicated by the second information is selected according to the combination with the operation mode of the slave device, and the selected gateway device It is characterized by transferring the downlink signal.

A communication control program according to a fifth aspect of the present invention comprises a child device, one or a plurality of gateway devices connected to the child device by wireless communication, relaying communication between each gateway device and a host device, and (1) an uplink signal received from the gateway device and destined for the higher-level device; When the uplink signal sent from the child device is received via a plurality of gateway devices, the uplink signal to which the strongest radio wave intensity information is added is transferred to the higher device. and (2) a downstream signal for selecting one of the gateway devices when a downstream signal is received from the host device and transferring the downstream signal to the selected gateway device. (3) the gateway that relays the upstream signal to which the strongest radio wave intensity information is added when receiving upstream signals including control signals to be transmitted by the slave units at the time of connection from the plurality of gateway devices; (4) for each slave unit, the control signal processing unit responds to the slave unit; (5) first storage means for storing first information associated with the gateway device that transmitted the downlink signal including the control signal; a second storage means for storing second information associated with the gateway device that is the relay source of the upstream signal transmitted from the slave unit to the host device when the upstream signal is transferred to the host device; (6) causing each of the gateway devices to function as gateway device management means for managing an operation mode set according to whether or not the gateway device has received the time synchronization signal; When receiving a downlink signal addressed to the child device from the host device, the transfer processing means is configured such that the operation mode of the gateway device indicated by the first information corresponding to the child device and the second information are Either the gateway device indicated by the first information or the gateway device indicated by the second information corresponding to the child device is selected and selected according to the combination with the operation mode of the indicated gateway device. the downlink signal to the gateway device is transferred.

A sixth aspect of the present invention is a child device, one or more gateway devices connected to the child device by wireless communication, relaying communication between each of the gateway devices and a host device, and each of the gateway devices In the communication method performed by a communication system comprising a communication control device for controlling communication, (1) each of the gateway devices includes time synchronization signal receiving means, a first communication unit, a second communication unit, and beacon transmission processing means, timing control means, downstream signal processing means , upstream signal processing means , and clock means ; (2) the time synchronization signal receiving means receives a time synchronization signal from the outside; (4) the second communication unit is capable of communicating with the communication control device; (6) the timing control means determines the timing at which the beacon transmission processing means transmits the beacon signal; (7) the downlink signal processing means, after a predetermined time has elapsed from the timing at which the beacon transmission processing means has transmitted the beacon signal, performs the first communication; (8) the upstream signal processing means, when the first communication unit receives an upstream signal from the slave device, (9) the clock means clocks the time in the gateway device; ( 10 ) the timing control means performs When the time-synchronized signal receiving means receives the time-synchronized signal, the time-synchronized signal receiving means controls at the first beacon transmission timing in which the timing interval is a constant period, and when the time-synchronized signal receiving means does not receive the time-synchronized signal, the A communication method, wherein control is performed with a second beacon transmission timing obtained by delaying a first beacon transmission timing by a predetermined delay time.

According to the present invention, it is possible to perform data transmission using a downstream signal to a slave device via a gateway device that cannot receive radio waves for time synchronization.

3 is a block diagram showing the functional configuration of a GW (gateway device) according to the embodiment; FIG. 1 is a block diagram showing an example of an overall configuration of a communication system according to an embodiment; FIG. 3 is a block diagram showing the functional configuration of a network server (communication control device) according to the embodiment; FIG. 4 is an explanatory diagram showing a configuration example of an EndDevice management table held by the network server according to the embodiment; FIG. FIG. 4 is an explanatory diagram showing a configuration example of a GW management table held by the network server according to the embodiment; 4 is a flow chart showing the operation when the GW according to the embodiment is activated. 4 is a timing chart showing a specific example of beacon signal transmission timing in the GW according to the embodiment; 7 is a flow chart showing operations when the network server according to the embodiment receives a control signal (DeviceTimeReq). 4 is a flow chart showing the operation when the network server according to the embodiment receives upstream data; 4 is a flow chart showing the operation when the network server according to the embodiment receives downstream data.

(A) Main Embodiments An embodiment of a communication system, a gateway device, a relay processing program, a communication control device, a communication control program, and a communication method according to the present invention will be described in detail below with reference to the drawings. In this embodiment, an example in which a gateway device and a communication control device are applied to a GW and a network server will be described.

(A-1) Configuration of Embodiment FIG. 2 is a block diagram showing the overall configuration of the communication system 1 of this embodiment.

The communication system 1 shown in FIG. 2 includes an application server 10 as a host device, a network server 20 as a communication control device, a GW 30 as a gateway device, and an EndDevice 40 as a child device.

The number of devices installed in the communication system 1 is not limited. For ease of explanation, in the communication system 1 of this embodiment, one network server 20, three GWs 30 (30-1 to 30-3), and one EndDevice 40 are arranged as shown in FIG. described as a thing.

In this embodiment, in principle, the communication system 1 is configured according to the standard specifications (LoRaWAN (TM) Specification v1.1, v1.0.3, etc.) defined by LoRaAlliance (TM) at the time of filing of the present application. It's becoming That is, in this specification, each device constituting the communication system 1 performs processing (operation) based on the specifications defined by LoRaAlliance (TM) for processing (operation) not particularly described below. In addition, hereinafter, the term “LoRa standard protocol” refers to the specifications defined by the LoRaAlliance (TM) at the time of filing the application.

Also, hereinafter, the wireless communication section between the EndDevice 40 and the GW 30 is referred to as a "LoRa wireless section". Then, in the network server 20, an ID for identifying each EndDevice 40 (for example, an address in the LoRa wireless section) and an ID for identifying each GW 30 (for example, IP addresses) are managed. In the following, the ID of EndDevice 40 is represented as "E1", and the IDs of GWs 30-1, 30-2 and 30-3 are represented as "G1", "G2" and "G3" respectively.

Next, the internal configuration of each device constituting the communication system 1 will be described.

First, the functional configuration of the GW 30 (30-1 to 30-3) will be explained using FIG. In this embodiment, it is assumed that each GW 30 has a configuration that can be shown by the block diagram of FIG.

As shown in FIG. 1, the GW 30 includes a wireless transmission unit 31, a wireless reception unit 32, a wired LAN transmission/reception unit 33, a GPS reception unit 34, a built-in clock unit 35, a random number generation unit 36, a Beacon transmission unit 37, a control unit 38, and LoRa It has a radio antenna 39 .

The control unit 38 has a function of controlling the entire GW 30 . The control unit 38 performs processing related to data transfer between the EndDevice 40 and the network server 20, for example.

In the GW 30, the LoRa radio antenna 39, the radio transmission section 31 and the radio reception section 32 constitute a radio communication interface (first communication section) for connecting to the LoRa radio section. That is, the GW 30 wirelessly communicates with the EndDevice 40 using the LoRa wireless antenna 39 , wireless transmitter 31 and wireless receiver 32 .

The LoRa radio antenna 39 is an antenna for radio wave transmission/reception with the LoRa radio section (EndDevice 40). The wireless transmission unit 31 has a function of transmitting wireless signals using the LoRa wireless antenna 39 . For example, the radio transmission unit 31 radio-modulates the data instructed by the control unit 38 according to the LoRa modulation method, and radio-transmits the data. The radio reception unit 32 has a function of receiving radio signals using the LoRa radio antenna 39 . The radio reception unit 32 demodulates the received radio waves according to the LoRa modulation method, for example, and passes the demodulated data to the control unit 38 .

The wired LAN transmission/reception unit 33 has a function of wired communication (second communication unit) in the GW 30 . The wired LAN transmission/reception unit 33 , for example, transmits data instructed by the control unit 38 to the wired LAN side (network server 20 side), or receives data from the wired LAN (network server 20 ) and passes it to the control unit 38 . process.

The GPS receiving unit 34 receives GPS radio waves (radio waves from GPS satellites; time-synchronized radio waves) using a GPS radio wave receiving antenna 341, and extracts data contained in the GPS radio waves (data including GPS time; time-synchronized signals). It has the function of obtaining The GPS receiver 34 supplies data obtained from GPS radio waves to the controller 38 .

The built-in clock section 35 has a function (internal clock means) for measuring time inside the GW 30 . The built-in clock unit 35 measures time (for example, adds a counter for measuring time) based on an internal clock signal (for example, a clock signal of a processor (not shown) constituting the control unit 38). It is responsible for the function of keeping time.

The control unit 38 corrects the time measured by the built-in clock unit 35 based on the GPS time included in the GPS radio waves received by the GPS receiving unit 34 . As a result, each GW 30 can realize synchronization of various timings (for example, synchronization of the timing of transmitting a beacon signal) with other GWs 30 . In this embodiment, the GW 30 implements means for acquiring timing for synchronizing with other GW 30 by receiving GPS radio waves. means is not limited to GPS.

The random number generator 36 has a function of generating random numbers (random numerical values). The random number generating section 36 may be realized by using random number generating means installed in a processor of a computer (not shown) that constitutes the control section 38 or the like, for example.

The beacon transmission unit 37 has a function of generating and transmitting a beacon signal (a beacon signal according to the LoRa standard protocol) at predetermined intervals (hereinafter referred to as “beacon intervals”). A beacon signal generated by the beacon transmission unit 37 is sent from the wireless transmission unit 31 (sent to the LoRa wireless section) via the control unit 38 .

In the GW 30, components that can be realized by software (for example, elements including the internal clock section 35, the random number generation section 36, the beacon transmission section 37, and the control section 38) are, for example, a computer not shown (for example, a processor, a memory , a computer configured by a hard disk (flash memory) or the like) by installing a program (including the relay processing program according to the embodiment).

Next, the functional configuration of the network server 20 will be explained using FIG.

As shown in FIG. 3 , the network server 20 has a wired LAN transmission/reception section 21 , a data storage section 22 and a control section 23 .

The control unit 23 has a function of controlling the network server 20 as a whole. The control unit 23 performs processing related to data transfer between the EndDevice 40 and the application server 10, for example.

The wired LAN transmission/reception unit 21 has a function of wired communication in the network server 20 . The wired LAN transmission/reception unit 21 , for example, transmits data instructed by the control unit 23 to the wired LAN side (the application server 10 or the network server 20 ), receives data from the wired LAN side, and passes the data to the control unit 23 . .

The data storage unit 22 is means for storing data used in processing of the control unit 23 . As the data storage unit 22, data storage means such as a hard disk or flash memory can be applied.

The data storage unit 22 of this embodiment stores an EndDevice management table 221 for managing which GW 30 each EndDevice 40 has communicated with, and a GW management table 222 for managing the state of each GW 30. . Detailed configurations of the EndDevice management table 221 and the GW management table 222 will be described later.

In the network server 20, components that can be realized by software (eg, the control unit 23 and the data storage unit 22) are implemented by, for example, a computer (eg, a computer configured by a processor, memory, hard disk (flash memory), etc.). It may be realized by installing a program (including the communication control program according to the embodiment).

Next, the Beacon signal transmission timing by GW30 is demonstrated.

The controller 38 of the GW 30 of this embodiment changes the downlink communication method (beacon signal transmission timing determination method) depending on whether the GPS receiver 34 can receive GPS radio waves. Hereinafter, this downlink communication method (beacon signal transmission timing determination method) is simply referred to as an “operation mode”. In this embodiment, when the GPS receiver 34 can receive GPS radio waves, the controller 38 of the GW 30 operates in an operation mode using Class B beacon signal transmission timing based on the LoRa standard protocol (hereinafter, “Class B mode” or (referred to as a "first operation mode"), and when the GPS receiver 34 cannot receive GPS radio waves, the beacon signal transmission timing is determined so as not to overlap with the Class B mode (first operation mode). (hereinafter referred to as "original Class B mode" or "second operation mode").

When operating in the Class B mode, the control unit 38 sets the transmission timing of the beacon every 128 seconds from January 6, 1980, which is the starting point of the GPS time, based on the time measured by the built-in clock unit 35. Then, the Beacon transmission unit 37 is controlled to execute the Beacon transmission process each time the Beacon transmission timing comes. While the control unit 38 operates in the Class B mode, the time measured by the built-in clock unit 35 is corrected based on the GPS time. cannot correct the time to be set.

Further, when operating in the original ClassB mode, the control unit 38 sets the Beacon signal transmission timing (hereinafter referred to as “Tb1”) determined in the ClassB mode to a delay time determined by a predetermined method. (hereinafter referred to as "Td") is delayed (hereinafter referred to as "Tb2"). That is, the Beacon signal transmission timing Tb2 in the original Classb mode is Tb1+Td.

In this embodiment, it is assumed that Td is set according to a random number (hereinafter referred to as "Nr") generated by the random number generator 36, but the method for determining Td is not limited to this. be.

Td may be set in the range of 0 to 128 sec (Beacon transmission interval in Class B mode), but it is desirable to set it in a range that does not overlap with the Beacon signal transmission timing of GW 30 operating in Class B mode.

For example, here, it is assumed that the period from when each GW 2 starts to ends the Beacon transmission is 20 msec or less. It is also assumed that the Beacon transmission interval in Class B mode is 128 sec. Furthermore, here, the lower limit of the range for setting Td is set to "Tdmin", and the upper limit of the range for setting Td is set to "Tdmax".

Then, in order not to overlap the Beacon signal transmission timing between the GW 30 in the original Class B mode and the GW 30 in the Class B mode, it is possible to set Tdmin>20msec and Tdmax<(128sec-20msec) (however, Tdmin<Tdmax). would be desirable. It should be noted that a larger difference between Tdmin and Tdmax is desirable in order to make it difficult for the beacon signal transmission timings of the GWs 30 operating in the unique Class B mode to overlap. Also, in order to make it difficult for the beacon signal transmission timings of the GWs 30 operating in the unique Class B mode to overlap, it is desirable that the grid width (setting unit) when the control unit 38 sets the delay time Td is short. For example, the control unit 38 may set the delay time Td in units of slots (30 msec) when timing between beacons in the LoRa standard protocol.

As described above, when operating in the unique Class B mode, the control unit 38 determines the delay time Td within the range of Tdmin to Tdmax based on the random number generated by the random number generation unit 36 . In this embodiment, it is assumed that the control unit 38 uses the initially determined delay time Td without updating it when operating in the unique Class B mode.

When the control unit 38 operates in the original Class B mode, it is preferable to continue using the delay time Td that has been determined once in order to perform stable communication with the EndDevice 40, but the delay time Td is updated at an arbitrary timing. You may make it For example, the control unit 38 may update the delay time Td every predetermined time.

Next, the configuration of the EndDevice management table 221 will be explained using FIG.

In the EndDevice management table 221, “EndDeviceID”, “DeviceTimeRsp transmission GW”, and “latest data reception GW” are registered for each EndDevice 40 . “EndDeviceID” is the ID of the EndDevice 40 concerned. “DeviceTimeRsp transmission GW” is the ID of GW 30 through which DeviceTimeRsp is sent back to EndDevice 40 in network server 20 . The “latest data reception GW” is the ID of the GW 30 that is the transfer source of the upstream data with the strongest radio wave intensity when the network server 20 recently received data from the EndDevice 40 .

Next, the configuration of the GW management table 222 will be explained using FIG.

In the GW management table 222, "GW_ID" and "operation mode" are registered for each GW30. “GW_ID” is the ID of the GW 30 concerned. The "operation mode" represents the operation mode of the GW 30, and is set to either the "original Class B mode" or the "Class B mode".

(A-2) Operation of Embodiment Next, the operation of the communication system 1 having the configuration as described above will be described.

First, the operation when the GW 30 is activated will be described using the flowchart of FIG.

When the controller 38 of the GW 30 is started (restarted), it performs initialization processing (for example, initialization of various parameters and cache) (S101).

Next, the control unit 38 controls the GPS receiving unit 34 to try to receive GPS radio waves (S102). If reception is not possible, the operation starts from step S103, which will be described later.

If the GPS radio wave cannot be received in step S102 described above, the control unit 38 starts up in the original Class B mode (S103).

When started in the unique ClassB mode, the control unit 38 notifies the network server 20 that the device itself will operate in the unique ClassB mode (S104), further causes the random number generation unit 36 to generate a random number, and the generated random number Then, the delay time Td is obtained based on (S105).

At this time, the control unit 23 of the network server 20 updates the data of the GW management table 222 (data of the operation mode corresponding to the ID of the GW 30 that received the notification) in accordance with the content of the notification.

The control unit 38 starts the process of beacon transmission (control of causing the beacon transmission unit 37 to transmit the beacon) at the timing (Tb+Td) obtained by delaying the timing Tb (beacon signal transmission timing in Class B mode) by the delay time Td (S106). ).

On the other hand, when the GPS radio wave can be received in the above step S102, the control unit 38 starts up in Class B mode (S107).

When activated in the ClassB mode, the control unit 38 starts the Beacon transmission process (control to cause the Beacon transmission unit 37 to transmit the Beacon) at the Beacon signal transmission timing Tb in the ClassB mode (S108).

As described above, the GW 30 selects a downlink communication mode (Class B mode or original Class B mode) at startup, and thereafter performs downlink communication (determination of the Beacon signal transmission timing) in the selected communication mode.

Next, an example of the beacon signal transmission timing of each GW 30 when the GW 30 operating in the Class B mode and the GW 30 operating in the unique Class B mode coexist will be described with reference to FIG.

Here, it is assumed that the GW management table 222 held by the network server 20 is in a state as shown in FIG.

That is, here, as shown in FIG. 5, the operation mode of GW30-1 is Class B mode, and the operation modes of GW30-2 and GW30-3 are original Class B mode. Here, the delay times acquired by GW30-2 and GW30-3 are represented by Td2 and Td3, respectively. Also, in the GW 30-1 operating in the Class B mode, arbitrary Beacon signal transmission timings are represented as "Tb1_1, Tb1_2, ...". Then, the Beacon signal transmission timings of GW 30-2 are “Tb1_1+Td2, Tb1_2+Td2, .

As shown in FIG. 5, in the communication system 1, the Beacon signal transmission timing of GW 30-1 operating in Class B mode and the Beacon signal transmission timing of GW 30-2 and GW 30-3 operating in original Class B do not overlap. . In addition, even if there are a plurality of GWs 30 operating in their own Class B, if the delay times Td obtained based on random numbers in each GW 30 do not match (Td2≠Td3), the Beacon between the GWs 30 operating in their own Class B Signal transmission timing results in non-overlapping.

Next, the operation when the EndDevice 40 participates in the LoRa network (connects to the network server 20 via one of the GWs 30) will be described with reference to the flowchart of FIG.

First, it is assumed that the EndDevice 40 sends out a DeviceTimeReq signal (sent to the LoRa radio section by a radio signal) in order to know the reception timing of the next Beacon signal in accordance with the procedure specified in the LoRa standard protocol. . Here, it is assumed that the DeviceTimeReq signal sent from EndDevice 40 is received by each of GW30-1 to GW30-3. Upon receiving the DeviceTimeReq from the EndDevice 40, the control unit 38 of the GW 30-1 to GW 30-3 records the radio wave strength (value of reception strength) at the time of receiving the DeviceTimeReq in accordance with the LoRa standard protocol, and records the received DeviceTimeReq. is added to the information of the radio wave intensity recorded in the , and transferred to the network server 20 .

As described above, here, the DeviceTimeReq sent from the EndDevice 40 is received by the network server 20 together with the value of the radio wave intensity (the radio wave intensity when received by each GW 30) via the GWs 30-1 to 30-3. (S201).

The control unit 23 of the network server 20 selects the GW 30 through which the DeviceTimeRsp is returned based on the value of the radio wave intensity added to the DeviceTimeReq received from each of the GWs 30-1 to 30-3. At this time, the control unit 23 of the network server 20 sets the ID of the selected GW 30 (the ID of the GW 30 with the strongest radio wave intensity) as the DeviceTimeRsp transmission GW corresponding to the EndDevice 40 in the EndDevice management table 221 (S202).

Then, the control unit 23 of the network server 20 transmits DeviceTimeRsp addressed to the EndDevice 40 to the selected GW 30 (S203).

Note that the process of the control unit 23 of the network server 20 receiving the DeviceTimeReq and returning the DeviceTimeRsp (including the process of selecting the GW 30 to pass through) itself can be performed in accordance with the LoRa standard protocol. can.

Next, the operation of the network server 20 when transferring uplink data (uplink data transfer) will be described with reference to the flowchart of FIG.

When uplink data (data to be transmitted with the application server 10 as the destination) is generated, the EndDevice 40 transmits the uplink data to the LoRa wireless section. When GW 30 (control unit 38 ) within the reception range of radio waves from EndDevice 40 receives upstream data from EndDevice 40 , it adds radio wave intensity to the received upstream data and transfers the data to network server 20 .

Then, the upstream data transferred from each GW 30 is received by the network server 20 (control unit 23) (S301).

At this time, the control unit 23 of the network server 20 receives transfer of upstream data from the plurality of GWs 30 . When receiving upstream data transfer from a plurality of GWs 30, the control unit 23 of the network server 20 refers to the value of radio wave intensity added to each received upstream data, and selects the upstream data with the strongest radio wave intensity. Determines to transfer to the application server 10, and sets the ID of the GW 30 (the GW 30 that is the transfer source of the upstream data with the strongest radio wave intensity) in the EndDevice management table 221 (the most recent data reception GW corresponding to the EndDevice 40) ( S302).

When there is uplink data received only from one GW 30, the control unit 23 of the network server 20 ignores the value of the radio wave intensity and transfers the ID of the GW 30 that is the transfer source of the uplink data to the EndDevice 40. may be set to the most recent data reception GW corresponding to .

Then, the control unit 23 of the network server 20 transfers the received upstream data (the upstream data received from the GW 30 with the strongest radio wave intensity) to the application server 10 (S303).

Note that the process itself when the control unit 23 of the network server 20 receives upstream data from a plurality of GWs 30 and transfers the data to the application server 10 can apply a procedure in accordance with the LoRa standard protocol.

Next, the operation of the network server 20 when transferring downstream data will be described with reference to the flowchart of FIG.

First, it is assumed that downstream data (downlink data) is transmitted from the application server 10 to the EndDevice 40 . Downstream data transmitted from the application server 10 is first received by the network server 20 (control unit 23) (S401). Note that the network server 20 already stores (registers) the ID of the EndDevice 40 that is the destination of the downstream data at the timing of receiving the downstream data from the application server 10 .

Then, the control unit 23 of the network server 20 acquires the destination (the ID of the EndDevice 40) of the received downlink data, and stores the DeviceTimeRsp transmission GW corresponding to the destination (the ID of the destination) and the latest data reception GW in the EndDevice management table 221. Get GW. Then, the control unit 23 of the network server 20 refers to the GW management table 222, and the operation mode of the GW 30 (hereinafter referred to as "first GW 30") corresponding to the acquired DeviceTimeRsp transmission GW and the acquired latest data The operation mode of the GW 30 corresponding to the receiving GW (hereinafter referred to as "second GW 30") is confirmed. Then, the control unit 23 of the network server 20 selects the GW 30 to be the transfer destination of the received downlink data according to the combination of the operation mode of the first GW 30 and the operation mode of the second GW 30 (first Either the GW 30 or the second GW 30 is selected) (S402, S403).

Here, as shown in steps S402 and S403 of FIG. 10, the control unit 23 of the network server 20, if the operation mode of the first GW 30 (DeviceTimeRsp transmission GW) is the GW of the original Class B mode (in S402 Yes), the first GW 30 (DeviceTimeRsp transmission GW) is selected as the transfer destination of the downlink signal. Further, here, the control unit 23 of the network server 20 determines that the operation mode of the first GW 30 (DeviceTimeRsp transmission GW) is a GW whose operation mode is the Class B mode (No in S402), and that the operation mode of the second GW 30 (most recent data reception GW) is If the operation mode is the unique Class B mode (No in S403), the first GW 30 (DeviceTimeRsp transmission GW) is selected as the transfer destination of the downlink signal. Further, here, the control unit 23 of the network server 20 determines whether the operation modes of the first GW 30 (DeviceTimeRsp transmission GW) and the second GW 30 (most recent data reception GW) are both Class B mode GW (No in S402). and Yes in S403), the second GW 30 (most recent data receiving GW) is selected as the transfer destination of the downlink signal. In other words, when either one of the operation mode of the first GW 30 or the operation mode of the second GW 30 is the original Class B mode, the control unit 23 of the network server 20 sends the first GW 30 (DeviceTimeRsp transmission GW) is selected as the forwarding destination of downstream data, and if not, the second GW 30 (most recent data receiving GW) is selected as the forwarding destination of downstream data.

When the first GW 30 (DeviceTimeRsp transmission GW) is selected as the transfer destination of the downlink signal, the control unit 23 of the network server 20 transmits the downlink data via the PingSlot of the first GW 30 (DeviceTimeRsp transmission GW). The first GW 30 (DeviceTimeRsp transmission GW) is instructed to transmit (S404).

On the other hand, when the second GW 30 (most recent data receiving GW) is selected as the forwarding destination of the downlink signal, the control unit 23 of the network server 20 transmits the data via the PingSlot of the second GW 30 (most recent data receiving GW) The second GW 30 (most recent data receiving GW) is instructed to transmit the downlink data (S405).

(A-3) Effects of Embodiment According to this embodiment, the following effects can be obtained.

In the communication system 1, the GW 30 that cannot receive GPS radio waves (for example, the GW 30 installed indoors) operates in the unique Class B mode. Specifically, in the communication system 1, the beacon signal transmission timing of the GW 30 that operates in the original Class B mode (the GW 30 that cannot receive GPS radio waves) is delayed by the delay time Td, so that the beacon signal transmission timing of the original Class B mode is delayed. can be controlled so as not to interfere (overlap) with the Beacon signal transmission timing in Class B mode. In other words, in the communication system 1, even if there is a GW 30 that cannot receive GPS radio waves, downlink data can be transmitted to the EndDevice 40 (slave device) that supports only the LoRa Class B communication method based on the LoRa standard protocol. .

Further, in this embodiment, the GW 30 operating in the unique Class B mode (the GW 30 unable to receive GPS radio waves) sets the delay time Td based on random numbers. Thereby, in the communication system 1 of this embodiment, even if there are a plurality of GWs 30 operating in the unique ClassB mode, it is possible to suppress the possibility of interference between Beacon transmissions between the GWs 30 operating in the unique ClassB mode.

In addition, in the network server 20 of this embodiment, by managing the EndDevice management table 221 and the GW management table 222, the operation mode of the first GW 30 (DeviceTimeRsp transmission GW) and the operation mode of the second GW 30 (most recent data reception GW) Know your mode of operation. Then, in the network server 20 of this embodiment, either the first GW 30 or the second GW 30 is selected as the forwarding destination of downstream data according to the combination of the operation mode of the first GW 30 and the operation mode of the second GW 30. are doing. Specifically, in the network server 20 of this embodiment, when either the operation mode of the first GW 30 or the operation mode of the second GW 30 is the original Class B mode, the first GW 30 (DeviceTimeRsp transmission GW) is selected as the forwarding destination of downstream data, and if not, the second GW 30 (most recent data receiving GW) is selected as the forwarding destination of downstream data. As a result, in the EndDevice 40 of the communication system 1 of this embodiment, the PingSlot of the GW 30 that transmitted the synchronized Beacon signal can more reliably receive downlink data (suppress downlink data reception failure).

(B) Other Embodiments The present invention is not limited to the above-described embodiments, and modified embodiments such as those illustrated below can also be mentioned.

(B-1) In the above embodiment, the network server 20 has the EndDevice management table 221 and the GW management table 222, updates these tables, and selects the GW 30 to which downlink data is to be transferred (Fig. 10 ), the processing of the network server 20 may be completely compliant with the LoRa standard protocol. In this case, the EndDevice management table 221 and the GW management table 222 are excluded from the network server 20, and each GW 30 also performs the process of reporting the operation mode of its own device to the network server 20 (the process of step S104 described above). You may make it exclude.

(B-2) In the communication system of the above embodiment, an example in which LoRa is applied has been described, but if the configuration requires an intermittent downlink using a Beacon signal similar to LoRa, other types of protocols may be replaced with

Reference Signs List 1 communication system 10 application server 20 network server 21 wired LAN transmission/reception unit 22 data storage unit 23 control unit 30, 30-1 to 30-3 GW 31 wireless transmission unit , 32... Wireless receiving unit 33... Wired LAN transmitting/receiving unit 34... GPS receiving unit 341... GPS receiving antenna 35... Built-in clock unit 36... Random number generating unit 37... Transmitting unit 38... Control unit 39... LoRa wireless antenna, 221...management table, 222...GW management table.

Claims (11)

Communication control for relaying communication between a child device, one or more gateway devices connected to the child device by wireless communication, and each of the gateway devices and a higher-level device, and controlling the communication of each of the gateway devices In a communication system comprising a device,
each said gateway device,
a time synchronization signal receiving means for receiving a time synchronization signal from outside the gateway device;
a first communication unit capable of transmitting and receiving radio signals to and from the child device;
a second communication unit communicable with the communication control device;
beacon transmission processing means for performing processing for transmitting a beacon signal to the child device via the first communication unit;
timing control means for determining the timing at which the beacon transmission processing means transmits the beacon signal, and causing the beacon transmission processing means to transmit the beacon signal at the determined timing;
downstream signal processing means for performing processing for transmitting a downstream signal addressed to the child device using the first communication unit after a predetermined time has elapsed from the timing at which the beacon transmission processing means transmitted the beacon signal; ,
Uplink signal processing means for, when the first communication unit receives an uplink signal from the child device, transferring the uplink signal from the second communication unit to the communication control device ;
clock means for measuring the time in the gateway device,
When the time-synchronous signal receiving means receives the time-synchronous signal, the timing control means controls the time-synchronous signal receiving means at a first beacon transmission timing in which the timing interval is a constant period, and the time-synchronous signal receiving means performs the time synchronization. A communication system, wherein when no signal is received, the first beacon transmission timing is controlled by a second beacon transmission timing delayed by a predetermined delay time. The gateway device
Time correction means for correcting the time based on the time synchronization signal
with
When the time synchronization signal receiving means receives the time synchronization signal, the timing control means determines the first beacon transmission timing based on the time corrected by the time correction means, and determines the time synchronization signal. 2. The communication system according to claim 1, wherein when the receiving means does not receive the time synchronization signal, the second beacon transmission timing is determined based on the time that has not been corrected by the time correcting means. The gateway device
When the time-synchronous signal receiving means receives the time-synchronous signal, the operation mode of the timing control means is set to the first operation mode, and when the time-synchronous signal receiving means does not receive the time-synchronous signal, the timing an operation mode setting means for setting the operation mode of the control means to a second operation mode;
The timing control means determines the first beacon transmission timing in the first operation mode, and determines the second beacon transmission timing in the second operation mode.
3. A communication system according to claim 1 or 2, characterized by: The gateway device comprises random number generating means for generating random numbers,
4. The communication system according to claim 1, wherein said delay time is a value based on said random number. said upstream signal processing means, when transferring an upstream signal to said communication control device, adds to said upstream signal radio wave intensity information when said first communication unit receives said upstream signal;
The communication control device is
When an upstream signal addressed to the higher-level device received from the gateway device is transferred to the higher-level device, and the up-link signal transmitted from the child device is received via a plurality of the gateway devices , an upstream signal transfer processing means for transferring an upstream signal to which information on the strongest radio wave intensity is added to the higher-level device;
Downlink signal transfer processing means for selecting one of the gateway devices and transferring the downlink signal to the selected gateway device when the downlink signal is received from the host device;
When receiving upstream signals including control signals that the slave unit sends out at the time of connection from a plurality of the gateway devices, the slave unit is sent to the gateway device that relayed the upstream signal to which the strongest radio wave intensity information is added. a control signal processing means for performing processing for transmitting a downlink signal including a control signal responding to the
a first storage means for storing, for each slave device, first information associated with the gateway device to which the control signal processing means transmits a downlink signal including a control signal responding to the slave device;
Correspondence with the gateway device that is the relay source of the upstream signal when the upstream signal transfer processing means transfers the upstream signal sent from the slave device with the host device as a destination to the host device, for each slave device. a second storage means for storing the attached second information;
a gateway device management means for managing an operation mode for each of the gateway devices, which is set according to whether or not the gateway device has received the time synchronization signal;
When the downstream signal transfer processing means receives a downstream signal destined for the child device from the higher-level device, the downstream signal transfer processing means selects an operation mode of the gateway device indicated by the first information corresponding to the child device and the second either the gateway device indicated by the first information or the gateway device indicated by the second information corresponding to the child device is selected according to the combination with the operation mode of the gateway device indicated by the information of , the downlink signal is transferred to the selected gateway device. The downlink signal transfer processing means, when receiving a downlink signal addressed to the child device from the higher-level device, at least determines the operation mode of the gateway device indicated by the first information corresponding to the child device, or the If any one of the operation modes of the gateway device indicated by the second information is set to the second operation mode, the gateway device indicated by the first information corresponding to the child device is selected, and When both the operation mode of the gateway device indicated by the first information corresponding to the child device and the operation mode of the gateway device indicated by the second information are set to the first operation mode, the child device 6. The communication system according to claim 5, wherein the gateway device indicated by the second information corresponding to the device is selected. Communication control for relaying communication between a child device, one or more gateway devices connected to the child device by wireless communication, and each of the gateway devices and a higher-level device, and controlling the communication of each of the gateway devices In the gateway device constituting a communication system comprising a device,
a time synchronization signal receiving means for receiving a time synchronization signal from outside the gateway device;
a first communication unit capable of transmitting and receiving radio signals to and from the child device;
a second communication unit communicable with the communication control device;
beacon transmission processing means for performing processing for transmitting a beacon signal to the child device via the first communication unit;
timing control means for determining the timing at which the beacon transmission processing means transmits the beacon signal, and causing the beacon transmission processing means to transmit the beacon signal at the determined timing;
downstream signal processing means for performing processing for transmitting a downstream signal addressed to the child device using the first communication unit after a predetermined time has elapsed from the timing at which the beacon transmission processing means transmitted the beacon signal; ,
Uplink signal processing means for, when the first communication unit receives an uplink signal from the child device, transferring the uplink signal from the second communication unit to the communication control device ;
a clock means for measuring the time in the gateway device,
When the time-synchronous signal receiving means receives the time-synchronous signal, the timing control means controls the time-synchronous signal receiving means at a first beacon transmission timing in which the timing interval is a constant period, and the time-synchronous signal receiving means performs the time synchronization. When no signal is received, the first beacon transmission timing is controlled by a second beacon transmission timing delayed by a predetermined delay time.
A gateway device characterized by: Communication control for relaying communication between a child device, one or more gateway devices connected to the child device by wireless communication, and each of the gateway devices and a higher-level device, and controlling the communication of each of the gateway devices a time synchronization signal receiving means for receiving a time synchronization signal from outside the gateway device; a first communication unit capable of transmitting and receiving a radio signal to and from the child device; a computer installed in a gateway device having a second communication unit capable of communicating with the communication control device,
beacon transmission processing means for performing processing for transmitting a beacon signal to the child device via the first communication unit;
timing control means for determining the timing at which the beacon transmission processing means transmits the beacon signal, and causing the beacon transmission processing means to transmit the beacon signal at the determined timing;
downstream signal processing means for performing processing for transmitting a downstream signal addressed to the child device using the first communication unit after a predetermined time has elapsed from the timing at which the beacon transmission processing means transmitted the beacon signal; ,
Uplink signal processing means for, when the first communication unit receives an uplink signal from the child device, transferring the uplink signal from the second communication unit to the communication control device;
functioning as clock means for measuring the time in the gateway device;
When the time-synchronous signal receiving means receives the time-synchronous signal, the timing control means controls the time-synchronous signal receiving means at a first beacon transmission timing in which the timing interval is a constant period, and the time-synchronous signal receiving means performs the time synchronization. When no signal is received, the first beacon transmission timing is controlled by a second beacon transmission timing delayed by a predetermined delay time.
A relay processing program characterized by: Communication control for relaying communication between a child device, one or more gateway devices connected to the child device by wireless communication, and each of the gateway devices and a higher-level device, and controlling the communication of each of the gateway devices In the communication control device constituting a communication system comprising a device,
When an upstream signal addressed to the higher-level device received from the gateway device is transferred to the higher-level device, and the up-link signal transmitted from the child device is received via a plurality of the gateway devices , upstream signal transfer processing means for transferring an upstream signal to which information on the strongest radio wave intensity is added to the higher-level device;
Downlink signal transfer processing means for selecting one of the gateway devices and transferring the downlink signal to the selected gateway device when a downlink signal is received from the host device;
When uplink signals containing control signals that the slave unit sends out at the time of connection are received from a plurality of the gateway devices, the slave unit is sent to the gateway device that relayed the uplink signal to which the strongest radio wave intensity information is added. a control signal processing means for performing processing for transmitting a downlink signal including a control signal responding to the
a first storage means for storing, for each slave device, first information associated with the gateway device to which the control signal processing means transmits a downlink signal including a control signal responding to the slave device;
Correspondence with the gateway device that is the relay source of the uplink signal when the uplink signal transfer processing means transfers the uplink signal sent from the handset to the host device most recently with the host device as the destination, for each of the child devices. a second storage means for storing the attached second information;
a gateway device management means for managing an operation mode for each of the gateway devices, which is set according to whether or not the gateway device has received a time synchronization signal;
When the downstream signal transfer processing means receives a downstream signal destined for the child device from the higher-level device, the downstream signal transfer processing means selects an operation mode of the gateway device indicated by the first information corresponding to the child device and the second either the gateway device indicated by the first information or the gateway device indicated by the second information corresponding to the child device is selected according to the combination with the operation mode of the gateway device indicated by the information of , a communication control device that transfers the downlink signal to the selected gateway device. Communication control for relaying communication between a child device, one or more gateway devices connected to the child device by wireless communication, and each of the gateway devices and a higher-level device, and controlling the communication of each of the gateway devices a computer installed in the communication control device constituting a communication system comprising a device,
When an upstream signal addressed to the higher-level device received from the gateway device is transferred to the higher-level device, and the up-link signal transmitted from the child device is received via a plurality of the gateway devices , upstream signal transfer processing means for transferring an upstream signal to which information on the strongest radio wave intensity is added to the higher-level device;
Downlink signal transfer processing means for selecting one of the gateway devices and transferring the downlink signal to the selected gateway device when a downlink signal is received from the host device;
When uplink signals containing control signals that the slave unit sends out at the time of connection are received from a plurality of the gateway devices, the slave unit is sent to the gateway device that relayed the uplink signal to which the strongest radio wave intensity information is added. a control signal processing means for performing processing for transmitting a downlink signal including a control signal responding to the
a first storage means for storing, for each slave device, first information associated with the gateway device to which the control signal processing means transmits a downlink signal including a control signal responding to the slave device;
Correspondence with the gateway device that is the relay source of the uplink signal when the uplink signal transfer processing means transfers the uplink signal sent from the handset to the host device most recently with the host device as the destination, for each of the child devices. a second storage means for storing the attached second information;
Each of the gateway devices functions as gateway device management means for managing an operation mode set according to whether or not the gateway device has received a time synchronization signal;
When the downstream signal transfer processing means receives a downstream signal destined for the child device from the higher-level device, the downstream signal transfer processing means selects an operation mode of the gateway device indicated by the first information corresponding to the child device and the second either the gateway device indicated by the first information or the gateway device indicated by the second information corresponding to the child device is selected according to the combination with the operation mode of the gateway device indicated by the information of , a communication control program for transferring the downlink signal to the selected gateway device. Communication control for relaying communication between a child device, one or more gateway devices connected to the child device by wireless communication, and each of the gateway devices and a higher-level device, and controlling the communication of each of the gateway devices In a communication method performed by a communication system comprising a device,
Each of the gateway devices includes time synchronization signal receiving means, a first communication section, a second communication section, beacon transmission processing means, timing control means, downlink signal processing means , uplink signal processing means and clock means ,
The time synchronization signal receiving means receives a time synchronization signal from the outside,
The first communication unit is capable of transmitting and receiving wireless signals to and from the child device,
The second communication unit is capable of communicating with the communication control device,
The beacon transmission processing means performs processing for transmitting a beacon signal to the child device via the first communication unit,
The timing control means determines the timing at which the beacon transmission processing means transmits the beacon signal, and causes the beacon transmission processing means to transmit the beacon signal at the determined timing;
The downstream signal processing means uses the first communication unit to transmit a downstream signal addressed to the child device after a predetermined time has passed from the timing at which the beacon transmission processing means transmits the beacon signal. and
the upstream signal processing means, when the first communication unit receives an upstream signal from the child device, performs processing for transferring the upstream signal from the second communication unit to the communication control device;
the clock means clocks the time in the gateway device;
When the time-synchronous signal receiving means receives the time-synchronous signal, the timing control means controls the time-synchronous signal receiving means at a first beacon transmission timing in which the timing interval is a constant period, and the time-synchronous signal receiving means performs the time synchronization. A communication method, wherein when no signal is received, the first beacon transmission timing is controlled with a second beacon transmission timing delayed by a predetermined delay time.

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