Aggregation system, communication node, and aggregation method

Abstract

To provide an aggregation system, etc. with which it is possible to avoid data collisions while suppressing the disposal of measured data.SOLUTION: The aggregation system comprises a first communication node that connects to a server using a first wireless circuit, a second communication node that connects to the first communication node using a second wireless circuit, and a server that aggregates measured data from the second communication node via the first communication node, or from the first communication node, using the first wireless circuit. The first communication node includes a notification unit that notifies each second communication node of the reconnection processing start time and scheduled processing time with the first wireless circuit, and an assignment unit that assigns a different number for each second communication node when a connection request from a second communication node is detected. The second communication node includes a calculation unit that calculates a wait time on the basis of the assigned number and the scheduled processing time, and a transmission unit that transmits measured data in a time slot other than the calculated wait time to the first communication node, using the second wireless circuit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an aggregation system, a communication node, and an aggregation method. [Background Art]

[0002] For example, with the development of IoT (Internet of Things) technology, the number of smart meters has increased. For example, aggregation systems that transmit measurement data such as electric energy measured by smart meters to a host system using an LTE (Long Term Evolution) line have become widespread. Furthermore, there is also known an aggregation system in which not only an NCU (Network Control Unit) but also other communication nodes are connected under a communication node connected to a 1:N wireless connection network such as an LTE line, for example, via a 920 MHz power-saving wireless line. By using the 920 MHz power-saving wireless line instead of the LTE line, packet charging in the LTE network is reduced.

[0003] In addition, communication nodes in an LTE network are not in a state of continuous communication for 24 hours, and are operated to disconnect communication once every 24 hours for the purpose of communication monitoring on the carrier side. Therefore, in order to avoid unintended communication disconnection, it is conceivable to adopt a mechanism in which a communication node that is LTE-connected to a host system disconnects communication with the LTE line at a cycle of, for example, 23 hours, and then reconnects to the LTE line. As a result, forced communication disconnection can be avoided. [Prior Art Literature] [Patent Literature]

[0004] [Patent Literature 1] Japanese Unexamined Patent Publication No. 2008-245102 [Patent Literature 2] Japanese Unexamined Patent Publication No. 2006-211232 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, as the number of smart meters connected within the aggregation system increases, the amount of measurement data transmitted from the NCU to the higher-level system increases, and the transmission frequency also increases. As a result, measurement data is sent to the communication node while it is in the process of reconnecting, and the data is discarded.

[0006] Furthermore, the next-generation smart meter aggregation system is being considered for connection not only with power companies but also with gas companies and water utilities. For example, it is being considered to connect the power company's aggregation system to gas company gas meters and water utility water meters. Therefore, the higher-level system will handle data from other companies, so it is necessary to avoid data collisions while minimizing data loss as much as possible.

[0007] One aspect of this is to provide an aggregation system that can avoid data collisions while suppressing the discarding of measurement data. [Means for solving the problem]

[0008] One embodiment of the aggregation system includes a first communication node connected to a higher-level system using a first wireless line, and a second communication node connected to the first communication node using a second wireless line. Furthermore, the aggregation system includes a higher-level system that aggregates measurement data from the second communication node or the first communication node via the first communication node using the first wireless line. The first communication node includes a first notification unit that notifies each second communication node of the start time and scheduled processing time for reconnection with the first wireless line, and a first assignment unit that, upon detecting a connection request from a second communication node, assigns a different first number to each second communication node. The second communication node includes a first calculation unit that calculates a waiting time based on the assigned first number and scheduled processing time, and a transmission unit that transmits measurement data to the first communication node using the second wireless line during time periods other than the calculated waiting time. [Effects of the Invention]

[0009] One aspect of this approach is that it can avoid data collisions while minimizing the discarding of measurement data. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is an explanatory diagram showing an example of the aggregation system of Example 1. [Figure 2] Figure 2 is an explanatory diagram showing an example of the functional configuration of the first communication node (second communication node) in Embodiment 1. [Figure 3] Figure 3 is an explanatory diagram showing an example of the functional configuration of an NCU. [Figure 4] Figure 4 is an explanatory diagram illustrating an example of the processing operation of the aggregation system during the search for a bypass source and the request for connection to a bypass source. [Figure 5] Figure 5 is an explanatory diagram showing an example of distributed waiting times. [Figure 6] Figure 6 is an explanatory diagram illustrating an example of the processing operation of the aggregation system related to the retransmission waiting time. [Figure 7] Figure 7 is an explanatory diagram showing an example of a retransmission waiting time. [Figure 8] Figure 8 is a flowchart showing an example of the processing operation of the first communication node involved in connection request processing. [Figure 9] Figure 9 is a flowchart showing an example of the processing operation of the first communication node involved in the reconnection start time update process. [Figure 10] Figure 10 is a flowchart showing an example of the processing operation of the first communication node involved in periodic notification processing. [Figure 11] Figure 11 is a flowchart showing an example of the processing operation of the second communication node involved in receiving data. [Figure 12] Figure 12 is a flowchart showing an example of the processing operation of the second communication node involved in the time update process. [Figure 13] Figure 13 is a flowchart showing an example of the processing operation of the second communication node involved in the registration process. [Figure 14]FIG. 14 is a flowchart illustrating an example of a processing operation of a second communication node involved in transmission processing. [Figure 15] FIG. 15 is a flowchart illustrating an example of a processing operation of an NCU involved in NCU-side transmission processing. [Figure 16] FIG. 16 is an explanatory diagram illustrating an example of a functional configuration of a first communication node (second communication node) according to the second embodiment. [Figure 17] FIG. 17 is an explanatory diagram illustrating an example of a processing operation of an aggregation system involved in firmware update processing according to the second embodiment. DESCRIPTION OF EMBODIMENTS

[0011] Hereinafter, embodiments of an aggregation system and the like disclosed in the present application will be described in detail with reference to the drawings. The disclosed technology is not limited by the present embodiment. Furthermore, the embodiments described below may be appropriately combined within a range that does not cause contradiction.

Embodiments

[0012] FIG. 1 is an explanatory diagram showing an example of the aggregation system 1 according to Embodiment 1. The aggregation system 1 shown in FIG. 1 includes a first communication node 2, a second communication node 3 subordinate to the first communication node 2, an NCU (Network Control Unit) 4 subordinate to the first communication node 2 and the second communication node 3, a base station 5, and a server 6. The first communication node 2 is a communication node connected to the server 6 using a first wireless line such as an LTE line, for example. The first communication node 2 is, for example, a smart meter of an electric power company. The second communication node 3 is wirelessly connected to the first communication node 2 using a second wireless line such as a 920 MHz power-saving wireless line, and is connected to the subordinate NCU 4 using the second wireless line. The second communication node 3 is, for example, a smart meter of an electric power company. The second communication node 3 is also connectable to the server 6 using the first wireless line. The NCU 4 is, for example, a water meter of a water supply bureau or a gas meter of a gas company, and is a third communication node that transmits measurement data to the upper first communication node 2 or the second communication node 3 using the second wireless line.

[0013] The base station 5 is a base station connected to a wireless communication network of the first wireless line. The server 6 is a host system that aggregates measurement data from the first communication node 2, the second communication node 3, and each NCU 4.

[0014] The first communication nodes 2 (second communication nodes 3) in the aggregation system 1 are arranged for each building, for example. For convenience of explanation, the case where the first communication node 2 (second communication node 3) is arranged for each building has been illustrated, but one communication node for a plurality of buildings is also acceptable, and can be changed as appropriate. Further, although the measurement data is exemplified by the measurement result of an electric power meter, the measurement result of a gas meter, and the measurement result of a water meter, the measurement data is not limited to these and can be changed as appropriate.

[0015] Figure 2 is an explanatory diagram showing an example of the functional configuration of the first communication node 2 (second communication node 3) of Embodiment 1. Since the second communication node 3 has substantially the same configuration as the first communication node 2, the explanation of its overlapping configuration and operation will be omitted. The first communication node 2 shown in Figure 2 includes a wireless IF (Interface) 11, a memory 12, and a CPU (Central Processing Unit) 13. The wireless IF 11 includes a first communication IF 11A and a second communication IF 11B. The first communication IF 11A is a communication IF that connects to a first wireless line, such as an LTE line. The second communication IF 11B is a communication IF that connects to a second wireless line, such as a 920MHz low-power wireless line. The first wireless line is, for example, a public toll line, while the second wireless line is, for example, a free line. The second wireless connection is not limited to a free connection; it may be a paid connection that is cheaper than the first wireless connection, and can be changed as appropriate. Memory 12 stores various information. CPU 13 controls the entire first communication node 2.

[0016] Memory 12 includes a line information memory 12A, a node information memory 12B, a detour number memory 12C, and an NCU information memory 12D. Line information memory 12A is a memory that stores information related to the first wireless line. Node information memory 12B is a memory that stores information related to the second communication node 3 under the first communication node 2 and information related to its own first communication node 2. Node information memory 12B is an area that stores a detour number, which is a first number assigned to each identification piece of information that identifies the second communication node 3 under the first communication node 2, which is itself. Detour number memory 12C is a memory that stores the detour number assigned to it by the first communication node 2. The detour number is, for example, an integer number starting from "1". NCU information memory 12D is a memory that stores information related to the subordinate NCU 4. The NCU information memory 12D is an area that stores the NCU bypass number, which is a second number assigned to each identification piece of information that identifies a subordinate NCU4. The NCU bypass number is, for example, an integer number starting with "1".

[0017] The CPU 13 has, functionally, a first communication control unit 13A, a second communication control unit 13B, a third communication control unit 13C, and a time acquisition unit 13D. The first communication control unit 13A controls the first communication IF 11A which wirelessly connects to the first wireless line. The second communication control unit 13B controls the second communication IF 11B which wirelessly connects to the first communication node 2 via the second wireless line. The third communication control unit 13C controls the second communication IF 11B which wirelessly connects to the subordinate NCU 4 via the second wireless line. The time acquisition unit 13D is a clock unit that acquires the current time.

[0018] The second communication control unit 13B includes a first notification unit 21, a first assignment unit 22, and a transmission unit 23. The first notification unit 21 broadcasts a periodic packet containing the reconnection start time and connection processing time. The reconnection start time is the time at which the first communication node 2 starts the reconnection process to reconnect with the first wireless line when it detects a communication interruption that occurs every 23 hours. The connection processing time is the time required from when the first communication node 2 starts the reconnection process until the reconnection with the first wireless line is completed, for example, 60 seconds. The reconnection start time and connection processing time are stored in the line information memory 12A. The periodic packet is a packet that the first communication node 2 periodically transmits. The second communication node 3 determines the highest-ranking first communication node 2 from among the multiple first communication nodes 2 based on the reception level of the periodic packets from each first communication node 2.

[0019] The first assignment unit 22 assigns a different detour number to each of its subordinate second communication nodes 3 and transmits the detour number to the subordinate second communication nodes 3 using the second wireless line. The line information memory 12A stores the reconnection start time, reconnection processing time, and reference time. The reference time is the time used when calculating the distributed waiting time with other second communication nodes 3, and the details will be described later. The transmission unit 23 transmits the measurement data to the server 6 using the first wireless line if its own node is the first communication node 2, and transmits the measurement data to the first communication node 2 using the second wireless line if its own node is the second communication node 3.

[0020] The third communication control unit 13C includes a first calculation unit 24, a determination unit 25, a second assignment unit 26, a second calculation unit 27, and a third notification unit 28. The first calculation unit 24 calculates the distributed waiting time, which is the distributed waiting time for the first communication node 2, using the reconnection start time, connection processing time, reference time, and bypass number from the higher-level first communication node 2. The first calculation unit 24 calculates its own distributed waiting time using (reconnection start time + connection processing time) + (its own bypass number × reference time). The distributed waiting time is the timing at which the subordinate second communication node 3 transmits measurement data to the first communication node 2. Although the distributed waiting time is used as an example for the distributed waiting time, the unavailable time may also be the remaining reconnection time (= reconnection start time + connection processing time) of the first communication node 2 plus the time required to avoid collisions of measurement data from each second communication node 3 (= its own bypass number × reference time). The second communication node 3 may transmit its measurement data to the first communication node 2 during time periods other than the unavailable time periods calculated by its own node.

[0021] When the determination unit 25 receives measurement data from a subordinate NCU 4, it determines whether the first communication node 2 is in the process of reconnecting and whether the current time is before its own distributed waiting time. If the determination unit 25 determines that the first communication node 2 is in the process of reconnecting and the current time is before its own distributed waiting time, it determines that the first communication node 2 is either out of communication with the first wireless line or in the process of reconnecting. If the determination unit 25 determines that the first communication node 2 is either out of communication with the first wireless line or in the process of reconnecting, it will notify the subordinate NCU 4 of a forwarding NG packet, as described later. If the determination unit 25 determines that the first communication node 2 is not in the process of reconnecting, it determines that the first communication node 2 is connected to the first wireless line and will forward the measurement data received from the subordinate NCU 4 to the first communication node 2.

[0022] The second assignment unit 26 assigns a different bypass number to each NCU4 when the second communication node 3 receives a connection request from an NCU4. The second calculation unit 27 calculates the retransmission waiting time for each subordinate NCU4. The second calculation unit 27 calculates the retransmission waiting time for the NCU4 using (reconnection start time + connection processing time) + (its own bypass number × reference time) + (the NCU bypass number of the relevant NCU4 × bypass time). The retransmission waiting time is the time when the NCU4 retransmits its measurement data to the higher-level second communication node 3. After the second calculation unit 27 calculates the retransmission waiting time for the subordinate NCU4, the third notification unit 28 sends a forwarding NG packet including the retransmission waiting time to the subordinate NCU4 using the second wireless line.

[0023] Figure 3 is an explanatory diagram showing an example of the functional configuration of NCU4. The NCU4 shown in Figure 3 has a wireless IF 31, a memory 32, a CPU 33, and a measurement unit 34. The wireless IF 31 has a third communication IF 31A. The third communication IF 31A is a communication IF that wirelessly connects to the higher-level first communication node 2 or second communication node 3 via a second wireless line. The measurement unit 34 measures meters such as power meters, water meters, and gas meters to obtain measurement data. The memory 32 stores various information. The CPU 33 controls the entire NCU4.

[0024] Memory 32 includes a retransmission waiting time memory 32A and a measurement data memory 32B. The retransmission waiting time memory 32A is a memory that stores the retransmission waiting time assigned to the NCU4 itself. When the CPU 33 in the NCU4 receives a forwarding NG packet from the higher-level second communication node 3, it stores the retransmission waiting time in the forwarding NG packet in the retransmission waiting time memory 32A. The measurement data memory 32B is a memory that temporarily stores the measurement data, which is the measurement result of the measurement unit 34.

[0025] The CPU 33 has, functionally, a fourth communication control unit 33A and a time acquisition unit 33B. The fourth communication control unit 33A controls the third communication IF 31A, which wirelessly connects to the higher-level second communication node 3 using the second wireless line. The time acquisition unit 33B is a clock unit that acquires the current time. The fourth communication control unit 33A determines whether the current time is a retransmission waiting time. If the current time is a retransmission waiting time, the fourth communication control unit 33A transmits the measurement data stored in the measurement data memory 32B to the higher-level second communication node 3. If the current time is not a retransmission waiting time, the fourth communication control unit 33A waits for the retransmission of the measurement data.

[0026] Figure 4 is an explanatory diagram showing an example of the processing operation of the aggregation system 1 during the detour source search and detour source connection request. For the sake of explanation, the second communication node 3 for “n=1” and the second communication node 3 for “n=2” are communication nodes under the first communication node 2. The first communication node 2 communicates with the server 6 via the base station 5 through the first wireless line, and also communicates with the second communication nodes 3 for “n=1” and “n=2” under its control via the second wireless line. Detour source search is the process in which the second communication node 3 searches for the higher-level first communication node 2 as the detour source from multiple first communication nodes in response to periodic packets from each first communication node 2. Detour source connection request is the process in which the second communication node 3 requests a connection from the first communication node 2, which is the detour source.

[0027] In Figure 4, the first communication node 2 broadcasts a periodic packet during the detour source search (step S11). The periodic packet includes the reconnection start time and connection processing time of the first communication node 2. When each second communication node 3 receives a periodic packet from the first communication node 2, it identifies the first communication node 2 as the detour source based on the reception level of the periodic packet. If the second communication node 3 identifies the first communication node 2 as the detour source, it stores the reconnection start time and connection processing time contained in the periodic packet in the line information memory 12A.

[0028] For example, when a bypass connection request is made, the second communication node 3, where "n=1", sends a connection request to the first communication node 2 via the second wireless line (step S12A). When the first communication node 2 receives the connection request, it sends a connection response to the second communication node 3 via the second wireless line, including the bypass number of the second communication node 3 (step S13A). As a result, the second communication node 3 stores the bypass number "1" assigned to its node in the bypass number memory 12C.

[0029] Furthermore, the second communication node 3, for which "n=2", sends a connection request to the first communication node 2 via the second wireless link (step S12B). When the first communication node 2 receives the connection request, it sends a connection response to the second communication node 3 via the second wireless link, which includes a bypass number that identifies the second communication node 3 (step S13B). As a result, the second communication node 3 stores the bypass number "2" assigned to its node in the bypass number memory 12C.

[0030] Figure 5 is an explanatory diagram showing an example of distributed waiting times. The first communication node 2 identifies a reconnection start time at which it will begin the reconnection process to reconnect to the first wireless line after disconnecting communication with the first wireless line in a 23-hour cycle. The first communication node 2 recognizes the time from the reconnection start time to a predetermined connection processing time, for example 60 seconds, as the remaining reconnection time. Note that the second communication node 3 with "detour number n=1", the second communication node 3 with "detour number n=2", and the second communication node 3 with "detour number n=3" are second communication nodes 3 under the control of the first communication node 2.

[0031] The second communication node 3, for "n=1", stores the reconnection start time, connection processing time, reference time, and detour number "n=1". The second communication node 3 for "n=1" calculates the distributed waiting time as (reconnection start time + reconnection processing time (60 seconds) + (reference time 10 seconds × detour number 1)). When the distributed waiting time of reconnection start time + reconnection processing time (60 seconds) + (reference time 10 seconds × 1) is reached, the second communication node 3 and each NCU4 under its control begin transmitting measurement data. In other words, the second communication node 3 for "n=1" will transmit measurement data during time periods other than the time period from the reconnection start time to the distributed waiting time.

[0032] The second communication node 3 for “n=2” stores the reconnection start time, connection processing time, reference time, and detour number “n=2”. The second communication node 3 for “n=2” calculates the distributed waiting time as reconnection start time + reconnection processing time (60 seconds) + (reference time 10 seconds × detour number 2). The second communication node 3 for “n=2” starts transmitting measurement data from the second communication node 3 and each NCU4 under its control when it reaches the distributed waiting time of reconnection start time + reconnection processing time (60 seconds) + (reference time 10 seconds × 2). In other words, the second communication node 3 for “n=2” will transmit measurement data during time periods other than the time period from the reconnection start time to the distributed waiting time.

[0033] The second communication node 3 for “n=3” stores the reconnection start time, connection processing time, reference time, and detour number “n=3”. The second communication node 3 for “n=3” calculates the distributed waiting time as reconnection start time + reconnection processing time (60 seconds) + (reference time 10 seconds × detour number 3). The second communication node for “n=3” starts transmitting measurement data from the second communication node 3 and each NCU4 under its control when it reaches the distributed waiting time of reconnection start time + reconnection processing time (60 seconds) + (reference time 10 seconds × 3). In other words, the second communication node 3 for “n=3” will transmit measurement data during time periods other than the time period from the reconnection start time to the distributed waiting time.

[0034] Furthermore, assuming a reference time of 10 seconds, the second communication node 3 with "n=1" transmits the measurement data to the first communication node 2 during the 10-second period between its own distributed waiting time and the distributed waiting time calculated by the second communication node 3 with "n=2". Furthermore, the second communication node 3 with "n=2" transmits the measurement data to the first communication node 2 during the 10-second period between its own distributed waiting time and the distributed waiting time calculated by the second communication node 3 with "n=3".

[0035] Figure 6 is an explanatory diagram showing an example of the processing operation of the aggregation system 1 related to the retransmission waiting time. Note that the second communication node 3 shown in Figure 6 is the second communication node 3 under the first communication node 2, and NCU4 is the NCU4 under the second communication node 3.

[0036] The first communication node 2 calculates the remaining reconnection time, which is calculated as (reconnection start time + reconnection processing time). The second communication node 3, under the first communication node 2, calculates the retransmission waiting time for each NCU 4 using (reconnection start time + reconnection processing time) + (reference time × detour number) + (detour time × NCU detour number).

[0037] The second communication node 3 assumes that it received a packet containing measurement data from its subordinate NCU 4 during the time remaining for reconnection + (reference time × detour number) (step S21). Note that the packet containing measurement data is the packet containing measurement data measured by NCU 4.

[0038] If the second communication node 3 receives a packet containing measurement data from its subordinate NCU 4 during the remaining reconnection time + (reference time × detour number), it determines that the first communication node 2 is in the process of reconnecting to the first wireless line and calculates the retransmission waiting time (step S22). The second communication node 3 calculates the retransmission waiting time for the NCU 4 using (reconnection start time + reconnection processing time) + (reference time × detour number) + (detour time × NCU detour number).

[0039] Furthermore, the second communication node 3 sends a forwarding NG notification, including the calculated retransmission waiting time, to its subordinate NCU4 (step S23). When the subordinate NCU4 receives the forwarding NG notification, it extracts the retransmission waiting time from the notification, and if the current time reaches the retransmission waiting time, it retransmits a packet containing the measurement data to the second communication node 3 (step S24).

[0040] When the second communication node 3 receives a packet containing measurement data from its subordinate NCU 4, it transmits the packet containing the measurement data to the first communication node 2. Furthermore, when the first communication node 2 receives a packet containing measurement data (step S24A), it transmits the packet containing the measurement data to the server 6 via the first wireless line (step S24B).

[0041] Figure 7 is an explanatory diagram showing an example of a retransmission waiting time. The second communication node 3 shown in Figure 7 calculates the retransmission waiting time for each of its subordinate NCUs 4 and assigns the retransmission waiting time to each subordinate NCU 4. The subordinate NCUs 4 of the second communication node 3 are, for example, NCU 4 with "NCU bypass number m=1" and NCU 4 with "NCU bypass number m=2". The reconnection time in this explanation is 60 seconds, the reference time is 10 seconds, and the bypass time is 1 second.

[0042] The second communication node 3 calculates its own distributed waiting time based on (reconnection start time + reconnection processing time + (reference time × detour number)). Furthermore, the second communication node 3 calculates the retransmission waiting time for NCU4 under NCU detour number "m=1" based on (reconnection start time + reconnection processing time + (reference time × detour number) + (detour time × NCU detour number 1).

[0043] Furthermore, the second communication node 3 calculates the retransmission waiting time for NCU4 under NCU bypass number "m=2" based on (reconnection start time + reconnection processing time + (reference time × bypass number) + (detour time 1 second × NCU bypass number 2).

[0044] Figure 8 is a flowchart illustrating an example of the processing operation of the first communication node 2 involved in connection request processing. In Figure 8, the second communication control unit 13B within the first communication node 2 determines whether or not it has received a connection request from the second communication node 3 using the second wireless line (step S31). The second communication node 3 transmits a connection request to the first communication node 2 using the second wireless line based on the reception level of periodic packets from the first communication node 2.

[0045] If the second communication control unit 13B in the first communication node 2 receives a connection request from the second communication node 3 (step S31: Yes), it determines whether the second communication node 3 in the connection request is already registered (step S32). If the second communication node 3 in the first communication node 2 is already registered (step S32: Yes), the first assignment unit 22 in the first communication node 2 sends a connection response to the second communication node 3 that includes a bypass number to be assigned to the registered second communication node 3 (step S33). The first communication node 2 then completes the processing operation shown in Figure 8.

[0046] If the second communication control unit 13B in the first communication node 2 does not receive a connection request from the second communication node 3 (step S31: No), it terminates the processing operation shown in Figure 8. If the second communication node 3 of the connection request is not already registered (step S32: No), the second communication control unit 13B stores the identification information of the second communication node 3 of the connection request in the node information memory 12B (step S34).

[0047] The first assignment unit 22 stores the identification information in the node information memory 12B and then assigns a bypass number to the second communication node 3 of the connection request (step S35). After assigning the bypass number to the second communication node 3 of the connection request, the first assignment unit 22 stores the assigned bypass number in the node information memory 12B in association with the identification information of the second communication node 3 (step S36). After storing the bypass number in the node information memory 12B, the first assignment unit 22 proceeds to the process in step S33 to send a connection response including the bypass number to the second communication node 3. As a result, the second communication node 3 can recognize that it has been registered with the first communication node 2 and its own bypass number in response to the connection response from the first communication node 2.

[0048] Figure 9 is a flowchart showing an example of the processing operation of the first communication node 2 involved in the reconnection start time update process. In Figure 9, the first communication control unit 13A within the first communication node 2 determines whether or not it has detected the reconnection timing for the first wireless line (step S41). The reconnection timing is the timing at which the reconnection process automatically starts after communication with the first wireless line is disconnected at 23-hour intervals.

[0049] If the first communication control unit 13A detects the timing for reconnecting the first wireless line (step S41: Yes), it starts a reconnection process to reconnect to the first wireless line (step S42). After starting the reconnection process, the first communication control unit 13A updates the reconnection start time and the reconnection process duration (step S43), and then terminates the processing operation shown in Figure 9. If the first communication control unit 13A does not detect the timing for reconnecting the first wireless line (step S41: No), it terminates the processing operation shown in Figure 9.

[0050] Figure 10 is a flowchart showing an example of the processing operation of the first communication node 2 involved in periodic notification processing. In Figure 10, the second communication control unit 13B within the first communication node 2 determines whether or not it has detected the timing for sending a periodic packet (step S51). The timing for sending a periodic packet is a predetermined periodic timing.

[0051] If the second communication control unit 13B detects the timing for sending a periodic packet (step S51: Yes), it reads out the reconnection start time and the reconnection processing time (step S52).

[0052] Furthermore, the first notification unit 21 within the first communication node 2 broadcasts a periodic packet containing the read reconnection start time and reconnection processing time (step S53), and terminates the processing operation shown in Figure 10. Also, if the second communication control unit 13B has not detected the timing for sending the periodic packet (step S51: No), it terminates the processing operation shown in Figure 10.

[0053] Figure 11 is a flowchart showing an example of the processing operation of the second communication node 3 involved in the reception process. In Figure 11, the second communication control unit 13B within the second communication node 3 determines whether or not it has received a periodic packet from the first communication node 2 (step S61). If the second communication control unit 13B has received a periodic packet (step S61: Yes), it extracts the reconnection start time and reconnection processing time from the periodic packet (step S62). The second communication control unit 13B stores the reconnection start time and reconnection processing time in the node information memory 12B (step S63), and terminates the processing operation shown in Figure 11.

[0054] Furthermore, if the second communication control unit 13B has not received a periodic packet (step S61: No), it determines whether or not it has received a connection request response packet from the first communication node 2 (step S64).

[0055] If the second communication control unit 13B receives a connection request response packet (step S64: Yes), it extracts a bypass number from the connection request response packet (step S65). Furthermore, the second communication control unit 13B stores the extracted bypass number in the bypass number memory 12C (step S66), and terminates the processing operation shown in Figure 11.

[0056] If the second communication node 3 has not received a connection request response packet (step S64: No), it terminates the processing operation shown in Figure 11.

[0057] Figure 12 is a flowchart showing an example of the processing operation of the second communication node 3 involved in the time update process. In Figure 12, the third communication control unit 13C within the second communication node 3 determines whether or not it has detected the timing for transmitting the measurement data (step S71). If the third communication control unit 13C has detected the timing for transmitting the measurement data (step S71: Yes), it reads out the reconnection start time and the reconnection processing time (step S72).

[0058] The first calculation unit 24 in the second communication node 3 calculates the remaining reconnection time based on (reconnection start time + reconnection processing time) (step S73). After calculating the remaining reconnection time, the determination unit 25 in the second communication node 3 determines whether the first communication node 2 is in the process of reconnecting with the first wireless line and whether the current time is before the remaining reconnection time (step S74).

[0059] The first calculation unit 24 in the second communication node 3 calculates the distributed waiting time for its own node (step S75) if the first communication node 2 is undergoing reconnection processing and the current time is before the remaining reconnection time (step S74: Yes). The first calculation unit 24 calculates the distributed waiting time based on the remaining reconnection time + (detour number × reference time). After calculating the distributed waiting time for its own node, the first calculation unit 24 stores the distributed waiting time in memory (step S76) and terminates the processing operation shown in Figure 12.

[0060] The third communication control unit 13C terminates the processing operation shown in Figure 12 if it has not detected the timing for transmitting the measurement data (step S71: No). Also, the second communication node 3 terminates the processing operation shown in Figure 12 if the first communication node 2 is not in the process of reconnecting, or if the current time is not before the remaining time for reconnection (step S74: No).

[0061] Figure 13 is a flowchart showing an example of the processing operation of the second communication node 3 involved in the registration process. In Figure 13, the third communication control unit 13C within the second communication node 3 determines whether or not it has received a registration request from its subordinate NCU 4 (step S81). If the third communication control unit 13C has received a registration request from its subordinate NCU 4 (step S81: Yes), it determines whether or not the NCU 4 of the registration request is already registered (step S82).

[0062] If the NCU4 for which registration is requested is not already registered (step S82: No), the third communication control unit 13C stores the NCU information of the NCU4 in the NCU information memory 12D (step S83). After storing the NCU information, the second assignment unit 26 in the second communication node 3 stores an NCU bypass number indicating the bypass order of the NCU4 in association with the NCU information (step S84). Furthermore, after storing the bypass number, the third communication control unit 13C sends a registration response to the NCU4 (step S85) and terminates the processing operation shown in Figure 13.

[0063] If the third communication control unit 13C does not receive a registration request from NCU4 (step S81: No), it terminates the processing operation shown in Figure 13. If the NCU4 of the registration request is already registered (step S82: Yes), the third communication control unit 13C proceeds to the processing in step S85 to send a registration request response to NCU4.

[0064] Figure 14 is a flowchart showing an example of the processing operation of the second communication node 3 involved in the transmission process. In Figure 14, the third communication control unit 13C within the second communication node 3 determines whether or not it has received measurement data from the subordinate NCU 4 (step S91). If the third communication control unit 13C has received measurement data from the subordinate NCU 4 (step S91: Yes), the determination unit 25 within the third communication control unit 13C determines whether the first communication node 2 is in the process of reconnecting with the first wireless line and whether the current time is before the remaining reconnection time (step S92).

[0065] The transmitting unit 23 in the second communication node 3 calculates the retransmission waiting time for the subordinate NCU4 if the first communication node 2 is in the process of reconnecting and the current time is before the remaining reconnection time (step S92: Yes) (step S94). The third notification unit 28 in the second communication node 3 notifies the subordinate NCU4 of a transfer NG notification including the calculated retransmission waiting time (step S95), and terminates the processing operation shown in Figure 14.

[0066] The second calculation unit 27 in the second communication node 3 transmits the measurement data to the first communication node 2 (step S93) and terminates the processing operation shown in Figure 14 if the first communication node 2 is not in the process of reconnecting, or if the current time is not before the remaining time for reconnection (step S92: No).

[0067] Furthermore, if the second communication node 3 has not received measurement data from the subordinate NCU 4 (step S91: No), it terminates the processing operation shown in Figure 14.

[0068] Figure 15 is a flowchart showing an example of the processing operation of NCU4 related to the NCU-side transmission process. The fourth communication control unit 33A in NCU4 shown in Figure 15 determines whether or not it has detected the timing for transmitting the measurement data (step S101). If the fourth communication control unit 33A has detected the timing for transmitting the measurement data (step S101: Yes), it transmits the measurement data to the higher-level second communication node 3 (step S102).

[0069] The fourth communication control unit 33A transmits the measurement data to the second communication node 3 and then determines whether or not it has received a transfer NG notification within a predetermined time (step S103). The predetermined time is the normal time from when the NCU 4 transmits the measurement data to the higher-level second communication node 3 until the transfer NG notification is received from the second communication node 3. If the fourth communication control unit 33A receives a transfer NG notification within the predetermined time (step S103: Yes), it extracts the retransmission waiting time from the transfer NG notification (step S104).

[0070] The fourth communication control unit 33A extracts the retransmission waiting time and then determines whether the current time is the retransmission waiting time (step S105). If the current time is the retransmission waiting time (step S105: Yes), the fourth communication control unit 33A retransmits the measurement data to the second communication node 3 (step S106) and terminates the processing operation shown in Figure 15.

[0071] If the fourth communication control unit 33A has not detected the timing for transmitting the measurement data (step S101: No), it terminates the processing operation shown in Figure 15. If the fourth communication control unit 33A has not received a transfer NG notification within a predetermined time (step S103: No), it terminates the processing operation shown in Figure 15. If the current time is not the retransmission waiting time (step S105: No), the fourth communication control unit 33A returns to the processing in step S105 to determine whether the current time is the retransmission waiting time.

[0072] In Example 1, the first communication node 2 broadcasts the reconnection start time and reconnection processing time to each of the second communication nodes 3. Furthermore, when the first communication node 2 detects a connection request from a second communication node 3, it assigns a different bypass number to each second communication node 3. The second communication node 3 calculates a distributed waiting time using the reconnection start time + reconnection processing time + (reference time × bypass number), and after the calculated distributed waiting time, transmits the measurement data to the first communication node 2 using the second wireless line. As a result, the second communication node 3 distributes the measurement data from its subordinate second communication nodes 3 at reference time intervals, thus avoiding measurement data collisions. This avoids the discarding of measurement data during the reconnection process of the first wireless line while also avoiding data collisions.

[0073] The first communication node 2 initiates a reconnection process to reconnect with the first wireless line in response to a communication interruption at a predetermined interval (23-hour cycle). As a result, data collisions can be avoided while avoiding the discarding of measurement data during the reconnection process of the first wireless line.

[0074] The second communication node 3 receives measurement data from its subordinate NCU 4, and if the first communication node 2 is in the process of reconnecting, it calculates the retransmission waiting time for the subordinate NCU 4 using the formula: reconnection start time + reconnection processing time + (reference time × detour number) + (detour time × NCU detour number). Furthermore, the second communication node 3 transmits the retransmission waiting time to the subordinate NCU 4. When the NCU 4 receives the retransmission waiting time from the second communication node 3, it transmits the measurement data to the second communication node 3 based on the retransmission waiting time. As a result, the second communication node 3 receives measurement data from the subordinate NCU 4 in a distributed manner at detour time intervals, thus avoiding collisions of measurement data. Moreover, it avoids the discarding of measurement data while the first wireless line is in the process of reconnecting.

[0075] In the aggregation system 1, the first communication node 2 periodically notifies its subordinate second communication node 3 of periods when communication is unavailable, such as distributed waiting times. Furthermore, upon receiving the notification of the period when communication is unavailable, the second communication node 3 determines whether the current time is during the reconnection process with the first wireless line for each measurement data transmission timing. If the current time is not during the reconnection process with the first wireless line, the second communication node 3 transfers the measurement data to the first communication node 2. If the current time is during the reconnection process with the first wireless line, the second communication node 3 cancels the transmission of the measurement data and notifies the NCU 4 to retransmit the measurement data after the retransmission waiting time has elapsed.

[0076] In aggregation system 1, multiple second communication nodes 3 and multiple NCUs 4 under the control of each second communication node 3, that is, the second communication nodes 3 and NCUs 4 under the control of the first communication node 2, can distribute the timing of measurement data transmission even if the number of subordinate nodes increases and the amount of measurement data increases, without individual instructions from the first communication node 2. The reason for distributing the data among the subordinate nodes is that the amount of data that the first communication node 2 can hold is finite, and it becomes more difficult to hold as the number of subordinate nodes increases.

[0077] For the sake of explanation, the example given shows that the second communication node 3 calculates the distributed waiting time using the reconnection start time + reconnection processing time + (reference time × detour number). However, the reconnection start time, reference time, and detour number can be changed as appropriate.

[0078] The second communication node 3 illustrates a case where the retransmission waiting time is calculated using the formula: reconnection start time + reconnection processing time + (reference time × detour number) + (detour time × NCU detour number). However, the reconnection start time, reconnection start time, reference time, detour number, detour time, and NCU detour number can be changed as appropriate.

[0079] Server 6 will handle data from other companies, such as water utilities, in addition to the power company, so it is necessary to avoid data collisions while minimizing data loss. Furthermore, it is desirable to avoid storing data from other companies at the first communication node 2 and the second communication node 3. Therefore, in this embodiment, by taking into account distributed waiting times and retransmission waiting times, it is not necessary to store data from other companies, and data collisions can be avoided.

[0080] In the aggregation system 1 of Example 1, the example illustrates a case where measurement data from the first communication node 2, the second communication node 3, and the NCU4 is aggregated by the server 6. However, the aggregation target is not limited to measurement data. It can also be applied to collection systems where the server 6 collects any data from the first communication node 2, the second communication node 3, and the NCU4. [Examples]

[0081] Figure 16 is an explanatory diagram showing an example of the functional configuration of the first communication node 2 (second communication node 3) in Embodiment 2. The first communication node 2 shown in Figure 16 has a wireless IF 11, a memory 12, and a CPU 13. The memory 12 has a line information memory 12A, a node information memory 12B, a bypass number memory 12C, and an NCU information memory 12D, as well as a firmware memory 12E. The firmware memory 12E is a memory that stores the firmware used by the first communication node 2. The first communication node 2 receives firmware from the server 6 via the first wireless line and stores the received firmware in the firmware memory 12E.

[0082] Furthermore, the first communication control unit 13A within the first communication node 2 receives the split firmware to be updated via the first wireless line and stores the received split firmware in the firmware memory 12E. The first communication control unit 13A then executes all the split firmware stored in the firmware memory 12E.

[0083] Furthermore, when the first communication node 2 receives a firmware distribution instruction from the server 6 using the first wireless line, it sequentially transmits the divided firmware stored in its memory to each of the subordinate second communication nodes 3 via one-hop multicast using the second wireless line. Each of the subordinate second communication nodes then sequentially receives the divided firmware from the first communication node 2 and sequentially stores the received divided firmware in the firmware memory 12E.

[0084] Figure 17 is an explanatory diagram showing an example of the processing operation of the aggregation system 1 involved in the firmware update process in Embodiment 2. In Figure 17, when updating the firmware, the server 6 sends the firmware distribution in block units to the first communication node 2. The server 6 divides the firmware into block units, and the destination addresses of the firmware packets are addresses destined for the first communication node 2 and its subordinate second communication node 3.

[0085] Server 6 transmits a firmware distribution, including the firmware after the division of block number "1", to the first communication node 2 using the first wireless link (step S121). When the first communication node 2 receives the firmware distribution, it determines whether the destination of the firmware distribution includes the address of the subordinate second communication node 3. If the destination of the firmware distribution includes the address of the subordinate second communication node 3, the first communication node 2 stores the firmware after the division of block number "1" in the firmware distribution in the firmware memory 12E. The first communication node 2 transmits an Ack to Server 6 using the first wireless link to indicate completion of the firmware distribution response (step S122).

[0086] Furthermore, Server 6 transmits a firmware distribution, including the firmware after the splitting of block number "2", to the first communication node 2 using the first wireless link (step S121A). When the first communication node 2 receives the firmware distribution, it determines whether the destination of the firmware distribution includes the address of the subordinate second communication node 3. If the destination of the firmware distribution includes the address of the subordinate second communication node 3, the first communication node 2 stores the firmware after the splitting of block number "2" in the firmware distribution in the firmware memory 12E. The first communication node 2 transmits an Ack to Server 6 using the first wireless link to indicate completion of the firmware distribution response (step S122A). Server 6 continues until all split firmware has been transmitted to the first communication node 2.

[0087] The server 6 then uses the first wireless link to send a firmware distribution to the first communication node 2, which includes the firmware after the division of the last block number "N" (step S121N). When the first communication node 2 receives the firmware distribution, it determines whether the destination of the firmware distribution includes the address of the subordinate second communication node 3. If the destination of the firmware distribution includes the address of the subordinate second communication node 3, the first communication node 2 stores the firmware after the division of block number "N" in the firmware distribution in the firmware memory 12E. The first communication node 2 then uses the first wireless link to send an Ack to the server 6 indicating completion of the firmware distribution response (step S122N). In other words, the first communication node 2 stores the firmware after the division of all blocks in the firmware memory 12E.

[0088] The server 6 then sends a firmware distribution instruction to the first communication node 2 (step S123). When the first communication node 2 detects the firmware distribution instruction, it determines whether or not there is updated firmware in the firmware memory 12E. If there is updated firmware in the firmware memory 12E, the first communication node 2 sets the destination of the packet to a multicast address and sets the hop count to 1. Then, using the second wireless line, the first communication node 2 sequentially transmits the firmware for each block number stored in the firmware memory 12E to each of the subordinate second communication nodes 3 using 1-hop multicast (step S124). Note that 1-hop multicast transmission is a multicast transmission of one hop. Although 1-hop multicast transmission is used as an example, 1-hop broadcast transmission is also acceptable and can be changed as appropriate.

[0089] After transmitting the firmware for the block number division, the first communication node 2 sequentially transmits the firmware for the next block number in its memory via one-hop multicast to each of the second communication nodes 3 under its control using the second wireless link (step S124A). The first communication node 2 continues to sequentially transmit the firmware for the next block number in its memory via one-hop multicast to each of the second communication nodes 3 under its control using the second wireless link until the transmission of firmware for all block numbers is complete. As a result, the first communication node 2 can distribute the firmware to the second communication nodes 3 under its control within a one-hop range using the second wireless link.

[0090] In the first communication node 2 of Embodiment 2, when it receives firmware from the server 6 using the first wireless line, it stores the received firmware in the firmware memory 12E. Furthermore, when the first communication node 2 detects a firmware distribution instruction, it transmits the firmware stored in the firmware memory 12E to the subordinate second communication node 3 via one-hop multicast using the second wireless line. As a result, since the firmware is distributed to the subordinate second communication node 3 using the second wireless line, the charges for the first wireless line can be reduced.

[0091] Furthermore, when the first communication node 2 detects a firmware distribution instruction, it determines whether or not there is new firmware that has been updated in the firmware memory 12E. If there is updated firmware in the firmware memory 12E, the first communication node 2 sets the destination of the packet to a multicast address and sets the hop count to 1. Then, using the second wireless line, the first communication node 2 sequentially transmits the firmware for each block number stored in the firmware memory 12E to each of the subordinate second communication nodes 3 via 1-hop multicast. However, when the first communication node 2 receives a firmware distribution, it determines whether or not the destination of the firmware distribution includes the address of one of the subordinate second communication nodes 3. If the destination of the firmware distribution includes one of the subordinate second communication nodes 3, the first communication node 2 stores the firmware for the block number in the firmware distribution in the firmware memory 12E. Furthermore, the first communication node 2 rewrites the destination of the firmware distribution to 1-hop multicast and transmits the firmware for the block number via 1-hop multicast. The subordinate second communication node 3 may receive the firmware of the block number received from the first communication node 2 and sequentially store it in the firmware memory 12E, and this can be changed as appropriate.

[0092] Furthermore, the components of each part shown in the diagram do not necessarily have to be physically configured as depicted. In other words, the specific forms of distribution and integration of each part are not limited to those shown in the diagram, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads, usage conditions, etc.

[0093] Furthermore, the various processing functions performed by each device may be executed in whole or in part on a CPU (Central Processing Unit) (or a microcomputer such as an MPU (Micro Processing Unit) or MCU (Micro Controller Unit)). It goes without saying that the various processing functions may also be executed in whole or in part on a program analyzed and executed by the CPU (or a microcomputer such as an MPU or MCU), or on wired logic hardware. [Explanation of Symbols]

[0094] 1. Aggregation System 2. First communication node 3. Second communication node 4 NCU 6 servers 21 First Notification Section 22 First granting section 23 Transmitter 24 First Calculation Unit 25 Judgment section 26 Second granting section 27 Second Calculation Unit 28 Third Notification Section

Claims

1. A first communication node that connects to a higher-level system using a first wireless link, A second communication node that connects to the first communication node using a second wireless link, The system includes a higher-level system that aggregates measurement data from the second communication node or the first communication node via the first communication node using the first wireless line, The first communication node is, A first notification unit that notifies each second communication node of the start time and scheduled time for the reconnection process with the first wireless line, A first assignment unit that, upon detecting a connection request from the second communication node, assigns a different first number to each of the second communication nodes, It has, The second communication node described above is A first calculation unit calculates a waiting time based on the assigned first number and the scheduled processing time, A transmitting unit that transmits the measurement data to the first communication node using the second wireless line during time periods other than the calculated waiting time, An aggregation system characterized by having the following features.

2. The first communication node is, The aggregation system according to claim 1, characterized in that it starts the reconnection process for reconnecting to the first wireless line in response to a predetermined periodic interruption of communication with the first wireless line.

3. The aggregation system according to claim 1, characterized in that it has a third communication node under the second communication node which acquires the measurement data to be aggregated and transmits the measurement data to the second communication node using the second wireless line.

4. The second communication node described above is A determination unit that, upon receiving the measurement data from the third communication node, determines whether the first communication node is in the process of reconnecting, When the first communication node is in the process of reconnection, a second calculation unit calculates a retransmission start time based on the scheduled processing time, the first number, and a second number that is different for each of the third communication nodes, It includes a second notification unit that notifies the third communication node corresponding to the second number of the calculated retransmission start time using the second wireless line, The third communication node described above is The aggregation system according to claim 3, characterized in that, upon receiving the retransmission start time from the second communication node, the system transmits the measurement data to the second communication node based on the retransmission start time.

5. The first calculation unit is, The aggregation system according to claim 1, characterized in that the waiting time is calculated using (reconnection start time + connection processing time + (reference time × first number)) based on the reconnection start time, connection processing time and reference time used in the processing schedule.

6. The second calculation unit described above is: The aggregation system according to claim 4, characterized in that it calculates the retransmission start time using (reconnection start time + connection processing time + (reference time × first number) + (detour time × second number) based on the reconnection start time, connection processing time and reference time used in the processing schedule.

7. A communication node that connects to a higher-level system using a first wireless link and a communication node that connects using a second wireless link, The aforementioned communication node, A calculation unit calculates the waiting time based on different numbers and scheduled processing times assigned by higher-level communication nodes, A transmitting unit that transmits measurement data to the higher-level communication node using the second wireless line during time periods other than the calculated waiting time, A communication node characterized by having the following features.

8. A first communication node that connects to a higher-level system using a first wireless link, A second communication node that connects to the first communication node using a second wireless link, A method for aggregating measurement data, comprising: a higher-level system that aggregates measurement data from a second communication node or the first communication node via the first communication node using the first wireless line, The first communication node is, The start time and scheduled processing time for the reconnection process with the first wireless line are notified to each second communication node. When a connection request from the second communication node is detected, a different number is assigned to each of the second communication nodes. It has, The second communication node described above is Based on the assigned number and the scheduled processing time, the waiting time is calculated. During periods other than the calculated waiting time, the measurement data is transmitted to the first communication node using the second wireless line. A method for aggregation characterized by performing a process.

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