TWI792875B - Communication system, hub device, central device, terminal, communication method, and recording medium - Google Patents

Abstract

The present disclosure discloes a communication system can constitute a wireless multi-hop hopping networks, the communication system includes a hub device (2) and a plurality of terminals (3) that send uploading data to the hub device (2). The hub device (2) uses an identification information of the terminal (3) through which an upload control signal, wherein the identification information is stored in the upload control signal sent from the source terminal, which is one of the plurality of terminals (3), to the hub device (2), and determines a plurality of downlink paths toward the source terminals, then using the determined plurality of downlink paths respectively to transmit the same downlink data whose destination is to the source terminal.

Description

Communication system, hub device, central device, terminal, communication method, and recording medium

The present disclosure relates to a communication system for performing multipoint hop communication, a line collection device, a central device, a terminal, a communication method and a recording medium.

In recent years, the interest in an energy-saving society has been increasing, and the introduction of automatic meter reading devices called smart meters, which can visualize power consumption and control the supply and demand of electricity, have been continuously promoted. . Smart meters are installed in all households and used as a wide-area large-scale network within the service range of each power company.

Most of the smart meters form a multi-hop network, and each smart meter sends measurement data to a concentrator serving as a root node in the multi-hop network. Generally speaking, a smart meter network that includes a multi-hop network of many smart meters has a plurality of hub devices, and a central device called a head-end system (HES: Head End System) collects each hub Measurement data collected by the device.

The previous smart meter network used RPL (IPv6 Routing Protocol for Low-Power and Lossy Networks; IPv6 Low-Power and Lossy Network Routing Protocol) as the routing protocol (Routing Protocol). In RPL, the selection of the downlink path from the hub device to the communication path of the smart meter is source routing, and the hub device at the main office specifies the route.

Patent Document 1 describes a technique in which a gateway as a line concentrator uses the information indicating the upload path recorded in the message in the upload direction from the smart meter to the line concentrator to determine the downlink path and perform source routing. . [Prior Art Literature] [Patent Document]

Patent Document 1: Japanese Patent Publication No. 6016646

[Problem to be Solved by the Invention]

In the technology described in the above-mentioned patent document 1, since a downlink path is set, when the downlink path is blocked, the smart meter cannot receive the downlink data. Therefore, in the technology described in Patent Document 1, when the downlink path is blocked, a downlink path search message is sent to search for a new downlink path, and a new downlink path is set using the response messages from each smart meter . As a result, a delay in downloading data occurs. However, the automatic meter reading of electricity is mainly the collection of measurement data from various smart meters, that is, upload communication, and the frequency of downlink communication is low, and a certain degree of delay can be tolerated, so even if the data described in Patent Document 1 is used The method is still no problem. However, in recent years, the use of a smart meter network constructed for automatic meter reading of electric power as an infrastructure is under review. For example, it is expected to be used to collect information of sensors used for control and monitoring of switches in power distribution systems. In this application, the downlink communication system requires higher reliability and lower latency than the current ones.

This disclosure was developed in view of the above-mentioned problems, and its purpose is to obtain a communication system capable of realizing highly reliable and low-latency downlink communication. [Means to solve the problem]

In order to solve the above-mentioned problems and achieve the purpose, the communication system disclosed in this disclosure can constitute a wireless multi-point hopping network, which includes more than one line concentrating device and a plurality of terminals that send uploaded data to the line concentrating device; The identification information of the terminal through which the upload signal is stored in the upload signal sent from one of the plurality of terminals to the hub device by the source terminal determines a plurality of downlink paths toward the source terminal; and uses the determined plurality downlink paths, respectively sending the same downlink data with the source terminal as the destination. [Efficacy of the invention]

The communication system disclosed in this disclosure achieves the effect of realizing downlink communication with high reliability and low delay.

Hereinafter, the communication system, the hub device, the central device, the terminal, the communication method and the recording medium of the embodiment will be described in detail according to the drawings.

Implementation type 1. FIG. 1 is a diagram showing a configuration example of a communication system of Embodiment 1. As shown in FIG. The communication system of this embodiment is used for automatic meter reading of electric power, but it can also be used for other purposes together with automatic meter reading of electric power. As shown in FIG. 1, the communication system of this embodiment includes a central device 1 as a communication management device, hub devices 2-1, 2-2, and terminals 3-1 to 3-12. The communication system of this embodiment includes line concentrating devices 2-1 and 2-2 as examples of more than one line concentrating device and terminals 3-1 to 3-12 as an example of a plurality of terminals, and can constitute a wireless multipoint Jump the net. Here, in FIG. 1 , two line concentrators and twelve terminals are shown, but the number of line concentrators and terminals is not limited to the example shown in FIG. 1 . The hub device can also be one.

The terminals 3-1 to 3-12 are communication devices connected to a measuring device not shown in the figure for measuring electric power, and each terminal 3-1 to 3-12 and its corresponding measuring device constitute a smart meter. That is, the terminals 3-1 to 3-12 are part of the smart electric meters, and transmit the measurement data of the electric power to the corresponding line concentrating devices 2-1 and 2-2. Measurement data is an example of uploaded data. The terminals 3-1 to 3-12 are, for example, installed at users of electric power. Also, when the communication system of this embodiment is used for purposes other than the automatic meter reading of electric power, the terminals 3-1 to 3-12 communicate with devices other than the measuring device due to the application, and will communicate from other devices. The data acquired by the device is sent to the corresponding hub device 2-1, 2-2. Hereinafter, when the terminals 3-1 to 3-12 are not individually distinguished, they are described as the terminal 3 and shown.

The line concentrating devices 2-1, 2-2 and the terminals 3-1 to 3-12 are configured as a wireless multi-hop network with the line concentrating devices 2-1, 2-2 as root nodes. Hereinafter, the hub devices 2-1, 2-2 and terminals 3-1 to 3-12 constituting the wireless multi-hop network will also be referred to as nodes. Here, the lines connecting the line concentrators 2-1, 2-2 and the terminals 3-1 to 3-12 in FIG. 1 represent wireless links. In addition, the following describes an example in which the communication system of this embodiment is a wireless multi-hop network, but it may also be a multi-hop network using power line communication or the like.

The hub devices 2-1 and 2-2 collect measurement data from the terminals 3-1 to 3-12, and send the collected measurement data to the central device 1 via the network. The network between the hub device 2-1, 2-2 and the central device 1 is an Internet Protocol (Internet Protocol; IP) network, such as an optical line network, a mobile phone network, but not limited to these networks . The line gathering devices 2-1 and 2-2 are installed on, for example, utility poles, etc., but the installation locations are not limited to utility poles. When the communication system of this embodiment is used for purposes other than automatic meter reading of electric power, the line concentrators 2-1 and 2-2 will receive the data from the terminals 3-1 to 3-12 for other purposes. The data are sent to the central device 1 via the network. Hereinafter, the line concentrators 2-1 and 2-2 are described as the line concentrator 2 when the line concentrators 2-1 and 2-2 are not individually distinguished.

The central device 1 collects measurement data from the hub devices 2-1 and 2-2, and sends the collected measurement data to a Meter Data Management System (MDMS) not shown in the figure. MDMS is a device for managing measurement data. Also, when the communication system of this embodiment is used for purposes other than the automatic meter reading of electric power, the central device 1 sends the data collected from the terminals 3-1 to 3-12 to the supplier for other purposes. Management devices, etc. used for other purposes. Moreover, the central device 1 sends control signals for controlling the terminals 3-1 to 3-12 to the terminals 3-1 to 3-12 through the hub devices 2-1 and 2-2. For example, when the communication system of this embodiment is used to control the switch of the power distribution system, the central device 1 receives a control signal for controlling the switch from the power distribution system management device that manages the power distribution system, and sends the control signal to the power distribution system. The switches correspond to terminals 3-1 to 3-12.

Next, a configuration example of each device constituting the communication system of this embodiment will be described. Fig. 2 is a diagram showing a configuration example of the central device 1 of the present embodiment. The central device 1 includes a transceiver unit 11 , a communication control unit 12 , a control processing unit 14 and a route information storage unit 13 . The path information storage unit 13 stores the corresponding relationship between the line concentrator 2 and the terminal 3 under the control of the line concentrator 2 as line concentrator information. The details of hub device information will be described later.

The transceiver unit 11 performs IP communication with the line concentrator 2 . The communication control unit 12 uses the line hub device information stored in the path information storage unit 13 to control the communication between the line hub devices 2-1, 2-2 and the terminals 3-1 to 3-12. For example, when the communication control unit 12 receives a control signal from the control processing unit 14 , if the received control signal is for the line hub device 2 , the transceiver unit 11 sends it to the corresponding line hub device 2 . Also, if the received control signal is to be sent to the terminal 3, the communication control unit 12 uses the line hub device information to obtain the line hub device 2 corresponding to the terminal 3, and sends the control signal to the terminal 3 via the transceiver unit 11. Find the hub device 2. Furthermore, when the communication control unit 12 receives the signals transmitted from the line concentrators 2-1, 2-2 and the terminals 3-1 to 3-12 via the transceiver unit 11, it outputs the signals to the control processing unit 14.

The control processing unit 14 generates control signals for controlling the line hub devices 2 - 1 , 2 - 2 and the terminals 3 - 1 to 3 - 12 and outputs them to the communication control unit 12 . Moreover, when the control processing part 14 receives the signal transmitted from the line concentrators 2-1, 2-2 and the terminals 3-1 to 3-12 via the communication control part 12, it uses this signal and performs predetermined processing. For example, when the received signal includes the measurement data of the electric power, it is temporarily stored in a not-shown memory unit, and is sent to the MDMS via the communication control unit 12 and the transceiver unit 11 at predetermined timing.

FIG. 3 is a diagram showing a configuration example of the line concentrator 2 of the present embodiment. The line hub device 2 includes a first transceiver unit 21 , a second transceiver unit 22 , a communication control unit 23 , a path information storage unit 24 and a control processing unit 25 . The path information storage unit 24 stores the downlink path information. The downlink path information stores information indicating a downlink path corresponding to the uplink path of the terminal known from the signal received from the terminal 3 . In this embodiment, the downlink path information stores a plurality of downlink paths for one terminal 3 . The details of the download path information will be described later.

The first transceiver unit 21 performs wireless communication with the terminal 3 . When the first transceiver unit 21 receives a signal from the terminal 3 , it outputs the signal to the communication control unit 23 . Also, the first transceiver unit 21 transmits various signals to the terminal 3 according to instructions from the communication control unit 23 . The second transceiver unit 22 performs IP communication with the central device 1 . When the second transceiver unit 22 receives a signal from the central device 1 , it outputs the signal to the communication control unit 23 . In addition, the second transceiver unit 22 transmits various signals to the central device 1 according to instructions from the communication control unit 23 .

When the communication control unit 23 receives a signal sent from the terminal 3 from the first transceiver unit 21, if the signal is an upload communication control signal used to construct a route, it will correspond to the upload route stored in the signal The downlink path, that is, the reverse downlink path of the upload path, is stored in the path information storage unit 24 as the downlink path information. Moreover, the communication control unit 23 uses the downlink path information to determine a plurality of downlink paths, and uses the plurality of downlink paths to send the same downlink data. When the communication control unit 23 receives a signal sent from the terminal 3 from the first transceiver unit 21, if the signal includes measurement data and other data to be sent to the central device 1, it outputs the data to the control process. Section 25. Also, when the communication control unit 23 receives a signal from the second transceiver unit 22, if the signal is sent to the self-terminal, it outputs the data contained in the signal to the control processing unit 25, if the signal is not In the case of sending to the own terminal, the signal is sent to the terminal 3 via the first transceiver unit 21 .

When the control processing unit 25 receives data such as measurement data sent from the terminal 3 via the communication control unit 23, it temporarily memorizes and delivers the data to the communication control unit 23 at a predetermined time sequence. The data of the communication control unit 23 is sent to the central device 1 via the second transceiver unit 22 .

FIG. 4 is a diagram showing a configuration example of the terminal 3 of this embodiment. The terminal 3 includes a transceiver unit 31 , a communication control unit 32 , a route information storage unit 33 and a control processing unit 34 . The route information storage unit 33 stores a terminal table in which upload route information indicating an upload route is stored. The details of the terminal table will be described later.

The transceiver unit 31 performs wireless communication with the hub device 2 or the terminal 3 of other nodes in the wireless multi-hop network. When the transceiver unit 31 receives a signal from another node, it outputs the signal to the communication control unit 32 . In addition, the transceiver unit 31 transmits signals to other nodes according to the instruction of the communication control unit 32 .

When receiving a signal from the transceiver unit 31, the communication control unit 32 outputs the data contained in the signal to the control processing unit 34 if the destination of the signal is sent to the own terminal. In the case of sending to another node, the transmitting and receiving unit 31 transmits the signal to the destination node and transfers the signal to the destination node. In addition, when the communication control unit 32 receives data such as measurement data from the control processing unit 34, it uses the terminal table stored in the route information storage unit 33 to transmit the data to the adjacent node in the upload direction via the transceiver unit 31. . The uploaded data is forwarded by each node to reach the destination node.

When the control processing unit 34 receives data from the communication control unit 32, it executes predetermined processing according to the received data. Also, the control processing unit 34 acquires data such as measurement data sent to the line concentrator 2 from another device such as a measurement device not shown, and outputs the acquired data to the communication control unit 32 .

Next, the hardware configuration of each device of this embodiment will be described. The transceiver part 11 of the central device 1 of this embodiment is realized by a transmitter and a receiver, and the communication control part 12 and the control processing part 14 are realized by a control circuit. The route information storage unit 13 is realized by a memory.

FIG. 5 is a diagram showing an example of the control circuit of this embodiment. The control circuit 100 shown in FIG. 5 is provided with a processor 101 such as a CPU (Central Processing Unit; a central processing unit), an MPU (Micro Processor Unit; a micro processing unit), and a memory 102. The memory 102 includes semiconductor memories such as RAM (Random Access Memory; Random Access Memory), ROM (Read Only Memory; Read Only Memory), and magnetic disks. The communication control part 12 and the control processing part 14 of the central device 1 are implemented by the processor 101 executing the communication program stored in the memory 102 for realizing the action of the central device 1. The communication program may be provided through recording media or communication media. In addition, the memory implementing the path information storage unit 13 can be a part of the memory 102 or a memory different from the control circuit.

In addition, generally speaking, the central device 1 is realized by a computer system, and in addition to the control circuit 100, it may also have a display unit such as a monitor, a display, etc., and an input unit such as a keyboard and a mouse, which are not shown in the figure.

The first transceiving unit 21 and the second transceiving unit 22 of the hub device 2 of this embodiment are realized by a transmitter and a receiver. The communication control unit 23 and the control processing unit 25 are realized by processing circuits. The path information storage unit 24 is realized by a memory. The processing circuit can be either the control circuit 100 shown in FIG. 5 , or a dedicated circuit such as FPGA (Field-Programmable Gate Array; field programmable gate array), ASIC (Application Specific Integrated Circuit; special application integrated circuit), etc. . When the communication control part 23 and the control processing part 25 are to be realized by the control circuit 100, the communication control part 23 and the control part 23 are realized by the processor 101 executing the communication program stored in the memory 102 for realizing the action of the hub device 2. Processing section 25. The communication program may be provided through recording media or communication media. In addition, the memory implementing the route information storage unit 24 can be a part of the memory 102 or a memory different from the control circuit.

The transceiver unit 31 of the terminal 3 of this embodiment is realized by a transmitter and a receiver. The communication control unit 32 and the control processing unit 34 are realized by a processing circuit, and the route information storage unit 33 is realized by a memory. The processing circuit can be either the control circuit 100 shown in FIG. 5 , or a dedicated circuit such as FPGA or ASIC. When the communication control part 32 and the control processing part 34 are to be realized by the control circuit 100, the communication control part 32 and the control processing are realized by the processor 101 executing the communication program stored in the memory 102 for realizing the operation of the terminal 3 Section 34. The communication program may be provided through recording media or communication media. In addition, the memory implementing the route information storage unit 33 can be a part of the memory 102 or a memory different from the control circuit.

The communication program of this embodiment is, for example, causing the communication system of this embodiment to execute the following steps: using the upload signal stored in the upload signal sent from one of the plurality of terminals 3 to the line hub device 2 The identification information of the passing terminal 3, the step of determining a plurality of downlink paths towards the source terminal; and the step of sending the same downlink data with the source terminal as a destination using the determined plurality of downlink paths.

Next, the operation of this embodiment will be described. FIG. 6 is a diagram showing an example of an upload path in this embodiment. Three paths of upload paths 4 - 1 to 4 - 3 are illustrated in FIG. 6 as upload paths from the terminal 3 - 9 toward the central device 1 . Each terminal 3 uses signals received from other terminals 3 to hold upload route information in a terminal table. The downlink path is determined by the hub device 2 using the uplink path stored in the signal received from each terminal 3 . The hub device 2 uses the determined downlink path to perform downlink communication through source routing. In the conventional smart meter network using RPL, the terminal 3 maintains a plurality of upload path information, but for the downlink path, the hub device 2 selects and maintains one downlink path according to each terminal 3 . Therefore, when there is a communication obstacle, a communication error, etc. in the downlink path, the terminal 3 cannot correctly receive the downlink signal sent from the hub device 2 . In the previous smart meter network using RPL, the hub device 2 detects an obstacle in the downlink path because it has not received a response signal from the terminal 3 for more than a certain period of time, and then constructs the downlink path and sends the downlink signal again However, due to the process of path reconstruction, there will be a large delay in the reception of the downlink signal at the terminal 3.

In this implementation mode, in order to improve the reliability of the downlink communication and reduce the delay, the line hub device 2 maintains a plurality of downlink paths according to each terminal 3 as the downlink path information, and continuously transmits the same data to the multiple downlink paths. route sent. In this way, downlink communication with high reliability and low delay is realized.

FIG. 7 is a sequence diagram showing an example of the route construction procedure in the communication system of this embodiment. FIG. 7 shows an example of the path construction sequence when the hub device 2-1 is newly connected to the communication system. First, the line concentrator 2-1 executes connection establishment processing with the central device 1 (step S1). Specifically, the second transceiver unit 22 of the line hub device 2-1 establishes a connection according to TCP (Transmission Control Protocol)/IP, and notifies the communication control unit 23 of the connection establishment when the connection is established.

Next, the hub device 2-1 sends a wireless multi-point hopping establishment signal for establishing a path in the wireless multi-point hopping network with the terminal 3 (step S2). Specifically, when the communication control unit 23 of the line hub device 2-1 receives the notification that the connection establishment is completed from the second transceiver unit 22, it generates a communication wireless multi-point hop construction signal, and broadcasts it via the first transceiver unit 21. (broadcast) to send communication wireless multipoint hop construction signals. The communication wireless multi-point hopping construction signal stores the line collection device ID (IDentifier; identifier) of the line collection device 2-1 uploading the root node of the communication, and stores the identification information of the node of the transmission source of the communication wireless multi-point hopping construction signal and the number of hops to reach hub 2-1. In the line hub device 2 - 1 , the identification information of the source node is the line hub device ID of the line hub device 2 - 1 , and the hop count is 0. The line hub device ID is identification information used to identify each line hub device 2 . In FIG. 7, the terminal 3-1 directly receives the wireless multi-point hopping construction signal from the line concentrating device 2-1, but the terminal 3-2, which is omitted from the illustration, also directly receives the wireless multi-point hopping construction signal from the line concentrating device 2-1, and The operations described below are performed in the same manner as the terminal 3-1.

When receiving the wireless multi-point hopping construction signal, the terminal 3-1 updates the hop number of the wireless multi-point hopping construction signal arriving at the hub device 2-1 and the identification information of the sending source node, and broadcasts the multi-point hopping path construction signal (step S3). The terminal ID is identification information used to identify each terminal 3 . Specifically, when the transceiver unit 31 receives a wireless multi-point hopping construction signal, it delivers the signal to the communication control unit 32, and the communication control unit 32 extracts the wireless multi-point hopping construction signal from the signal received from the transceiver unit 31. The identification information and hop count of the node from which the signal is sent. The communication control unit 32 updates the identification information of the source node in the signal received from the transceiver unit 31 to the terminal ID of the terminal 3-1, and updates the number of hops in the signal to the extracted number of hops plus 1 for the resulting value. In this example, the hop number extracted from the data received from the transceiver unit 31 is 0, so the communication control unit 32 of the terminal 3-1 updates the hop number to 1. The communication control unit 32 outputs the updated signal to the transceiver unit 31, and the transceiver unit 31 broadcasts the signal received from the communication control unit 32 as a multipoint hop path construction signal.

In addition, the terminal 3-1 sends an uplink communication control signal when receiving the wireless multi-point hopping establishment signal (step S4). Specifically, the communication control unit 32 grasps the line concentrator 2-1, which is the source node of the signal, from the wireless multipoint hopping construction signal received from the transceiver unit 31, and generates a message to be sent to the line concentrator 2-1. Uplink communication control signal, and store terminal ID of terminal 3 - 1 in the uplink communication control signal as identification information of node sending source, and transmit uplink communication control signal through transceiver 31 . Here, each terminal 3 may wait for a certain period of time without sending an upload control signal after receiving the wireless multipoint hopping construction signal, and when receiving the wireless multipoint hopping construction signal from a plurality of other terminals 3 within a certain period of time, according to The signal strength of the received wireless multi-point hopping construction signal is used to select the terminal 3 with good communication quality, and the upload communication control signal is sent to the selected terminal 3 . In addition, after receiving the wireless multi-point hopping construction signal, the upload control signal may not be sent, but the regularly sent upload communication signal, that is, the signal including the measurement data may be sent.

In addition, when the terminal 3-1 receives the wireless multi-point hopping establishment signal, it stores the upload path in the terminal table (step S5). Specifically, the communication control unit 32 stores the identification information of the source node of the wireless multipoint hop configuration signal received from the transceiver unit 31 and the hop number obtained by adding 1 to the hop number included in the signal. The terminal table in the route information storage unit 33 serves as upload route information related to the upload route. Fig. 8 is a diagram showing an example of a terminal table in this embodiment. The terminal table stores information related to n paths from upload path #1 to upload path #n. n is the number of upload paths held by each terminal 3 and is an integer greater than or equal to 2. n is determined in advance, but may be changed by an instruction from the central device 1 or the hub device 2 . The relevant information of each path includes the identification information of the next node in the path and the number of hops to reach the hub device 2 . Each terminal 3 stores the identification information of the node of the transmission source of the wireless multi-point hopping construction signal as the identification information of the next node of the upload path.

In the example shown in FIG. 7, the terminal 3-1 directly receives the wireless multi-point hopping configuration signal from the line hub device 2-1, because the identification information of the node of the transmission source of the wireless multi-point hopping configuration signal is that of the line hub device 2-1. The hub device ID, so in step S3, for example, uploading the information of path #1, the hub device ID of the hub device 2-1 is stored as the identification information of the next node, and 1 is stored as the hop number. Furthermore, the processing order of steps S3 to S5 is not limited to this example, and these can be performed simultaneously or in a different order from that shown in FIG. 7 . As described above, also in the terminal 3-2, steps S1 to S3 are performed in the same manner as the terminal 3-1.

On the other hand, as shown in FIG. 7, when the terminal 3-4 receives the wireless multi-point hopping construction signal sent from the terminal 3-1 in step S3, it updates the arrival line device 2- of the wireless multi-point hopping construction signal. The hop number of 1 and the identification information of the sending source node are broadcasted, and a multipoint hop path construction signal is broadcast (step S6). The terminal 3-4 updates the identification information of the source node in the received wireless multi-point hopping construction signal to the terminal ID of the terminal 3-4 in the same way as the above-mentioned terminal 3-1, and the The number of jumps is updated to a value obtained by adding 1 to the extracted number of jumps. In this example, terminals 3-4 update the hop count to 2.

Also, the terminal 3-4 transmits an uplink communication control signal destined for the hub device 2-1 in the same manner as the terminal 3-1 (step S7). Here, since the terminal 3-4 receives the wireless multipoint hopping configuration signal from the terminal 3-1, the terminal 3-4 sends the uplink communication control signal destined for the hub device 2-1 to the terminal 3-1.

Moreover, the terminal 3-4 stores the upload route in the terminal table similarly to the terminal 3-1 (step S8). Since the terminal 3-4 receives the wireless multi-point hop construction signal from the terminal 3-1, for example, the terminal ID of the terminal 3-1 is stored in the information of the upload path #1 as the identification information of the next node, and 2 is stored as the hop number . Here, the processing sequence of Step S6 to Step S8 is the same as the processing sequence of Step S3 to Step S5 and is not limited to this example, these steps can be performed simultaneously, and can also be performed in other sequences different from the sequence shown in FIG. 7 . Also, the terminal 3-5, which is not shown in the figure, receives the wireless multi-point hopping establishment signal transmitted from the terminal 3-1 in step S3, and performs steps S6 to S8 in the same manner as the terminal 3-4. Furthermore, the terminals 3-5 and 3-6 receiving the wireless multi-point hopping configuration signal from the terminal 3-2 also receive the wireless multi-point hopping configuration signal sent from the terminal 3-1 in step S3 in the same way as the terminal 3-4. signal, and implement steps S6 to S8.

Although illustration is omitted hereafter, even the terminals 3-8 and 3-9 receiving the wireless multi-point hopping configuration signal transmitted from the terminal 3-4 perform steps S6 to S8 in the same manner as the terminal 3-4. Also, similarly, the terminal 3 that receives the wireless multi-point hopping configuration signal from other terminals 3 also performs steps S6 to S8 in the same manner as the terminal 3-4 and is not limited to these terminals. Accordingly, in the configuration example shown in FIG. 6 , the terminal 3-9 receives the wireless multi-point hopping configuration signal sent from the hub device 2-1 from the terminal 3-4 and the terminal 3-5. Therefore, in the terminal table of the terminal 3-9, for example, the terminal ID of the terminal 3-4 is stored in the information of the upload path #2 as the identification information of the next node and 3 is stored as the hop number, and in the information of the upload path #2 The information stores the terminal ID of the terminal 3-5 as the identification information of the next node and stores 3 as the hop number. In this way, information of a plurality of upload paths is stored in the terminal table. Here, an upper limit can also be set for the number of hops, and when the number of hops extracted from the received wireless multi-point hop construction signal has reached the upper limit, the terminal 3 can also not implement steps S6 to S8.

Return to the description of FIG. 7 . When the terminal 3-1 receives the upload communication control signal sent out in the step S7, the identification information of the terminal 3-1 is added to the upload communication control signal (step S9), and the identification information number of the additional terminal 3-1 is passed. The upload communication control signal is sent to the hub device 2-1 (step S10). Specifically, when the transceiver unit 31 receives the upload communication control signal, it delivers the signal to the communication control unit 32, and the communication control unit 32 attaches the terminal 3-1 to the upload communication control signal received from the transceiver unit 31. The terminal ID. Furthermore, the communication control unit 32 transmits the upload communication control signal to which the terminal ID of the terminal 3 - 1 is added via the transceiver unit 31 to the next node of the upload route in the terminal table stored in the route information storage unit 33 . At this point, the terminal table of the terminal 3-1 only stores the next node as the upload path of the line hub device 2-1, so the communication control unit 32 sends the upload communication control signal to the line hub device 2-1 according to the information of the upload path. 1. Also, when the terminal table of the terminal 3-1 stores relevant information of a plurality of upload paths, the communication control unit 32 sends the upload communication control signal to the upload path selected according to the number of hops and communication quality.

When the hub device 2-1 receives the uplink communication control signal sent out in step S4, it records the downlink path of the terminal 3-1 (step S11), and when receiving the uplink communication control signal sent out in step S10, Just record the downlink path of the terminal 3-4 (step S12). Specifically, when the first transceiver unit 21 receives the upload communication control signal, it delivers the signal to the communication control unit 23, and the communication control unit 23 extracts the upload communication control signal from the first transceiver unit 21. Upload the terminal identification information of the terminal 3 on the path through which the communication control signal passes to grasp the upload path, and record the downlink path corresponding to the grasped upload path in the downlink path information of the path information storage unit 24 . Since the upload communication control signal sent in step S4 is directly sent from the terminal 3-1 to the hub device 2-1 without going through other terminals 3, the communication control unit 23 stores the terminal ID of the terminal 3-1 as a representation The downlink path information of the downlink path corresponding to the uplink path of the uplink communication control signal sent in step S4. Also, the upload communication control signal sent in step S10 is sent from the terminal 3-4 and is attached with the terminal ID of the terminal 3-1 via the terminal 3-1. Therefore, the communication control unit 23 records the terminal ID of the terminal 3-4 and the terminal ID of the terminal 3-1 as the downlink path information of the terminal 3-4 according to the uplink communication control signal sent in step S10. However, here, the downlink path information includes the terminal ID of the source of the uplink communication control signal, but since the downlink path information is managed by the terminal of each source, it represents the information of each downlink path It is also possible to store the terminal ID of the terminal 3 passed through.

Similarly, the hub device 2 - 1 sequentially receives the uplink communication control signals sent from the other terminals 3 , and adds a downlink path to the downlink path information in the path information storage unit 24 each time receiving. When a certain period of time has elapsed since the transmission of the wireless multi-point hopping construction signal in step S2 and the uplink communication control signal is received from all the terminals 3, the hub device 2-1 stores a plurality of downlink paths in each terminal using the uplink path according to each terminal. Downloading route information (step S13). Specifically, the communication control unit 23 is based on the terminal 3 of the destination of each downlink route, from the downlink route information in the route information storage unit 24, obtains and records according to the uplink communication control signal sent from the terminal 3. There are a plurality of downlink paths, and the obtained plurality of downlink paths are stored in the path information storage unit 24 as downlink path information.

FIG. 9 is a diagram showing an example of downlink route information in this embodiment. As shown in FIG. 9 , the downlink path information stores information representing p downlink paths from downlink path #1 to downlink path #p for each terminal 3 . p is an integer of 2 or more, and is predetermined. p may be changed by an instruction or the like from the central device 1 . However, in this case, step S13 is performed when a certain period of time has elapsed since the transmission of the wireless multi-point hopping construction signal, but the terminal 3 under the control of the line hub device 2-1 has been predetermined and set in the line hub device 2-1. Next, the communication control unit 23 may execute step S13 when the upload communication control signal has been received from all the terminals 3 predetermined as the terminals 3 under the control of the hub device 2-1. The so-called terminal 3 under the control of the line collection device 2-1 refers to the terminal 3 that uses the line collection device 2-1 as the root node to perform wireless multi-point hop communication, that is, the line collection device 2-1 is used to relay the central device 1 and the terminal 3 between the terminals 3 of the communication.

Next, the hub device 2-1 sends the terminal notification signal to the central device 1 (step S14). Specifically, the communication control unit 23 uses the downlink route information stored in the route information storage unit 24 to obtain the terminal ID of the terminal 3 under the control of the line hub device 2-1 and generate a control route including the line hub device 2-1. The terminal notification signal of the terminal ID of the terminal 3 below is sent to the central device 1 through the second transceiver unit 22 . Thereby, the central device 1 can grasp which terminal 3 exists under the control of the line concentrator 2-1. In the central device 1, when the transceiver unit 11 receives the terminal notification signal, it outputs to the communication control unit 12, and the communication control unit 12 uses the terminal notification signal to update the line hub device information in the path information storage unit 13. The line hub device information is information indicating the correspondence relationship between the terminal 3 and the line hub device 2 .

FIG. 10 is a diagram showing an example of line concentrator information in this embodiment. FIG. 10 shows the information related to the terminal 3-9 among the hub device information. In this example, it shows that the terminal 3-9 is under the control of the hub device 2-1. The central device 1 retains, as the line concentrator information, information indicating which line concentrator 2 the terminal 3 is under the control of in this way for each terminal 3 .

In FIG. 7 , the path construction operation in the case where the line concentrating device 2-1 is connected to the central device 1 is shown, but the same operation is performed when the line concentrating device 2-2 is connected. Accordingly, corresponding to one terminal 3, the hub device 2-2 maintains p downlink paths to the terminal 3 under control. Here, in this embodiment, the central device 1 predetermines one line hub device 2 corresponding to one terminal 3 . For example, as shown in Figure 6, the upload path from the terminal 3-9 to the central device 1 can consider the path via the line hub 2-1 and the path via the line hub 2-2, but the central device 1 is decided to use the line hub 2-1 and the line concentrating device 2-2 as the line concentrating device 2 corresponding to the terminal 3-9. Here, with regard to the upload path, each terminal 3 can first keep the primary and secondary line concentrators 2 as destinations, and can send the uploaded data to Secondary hub 2.

FIG. 11 is a diagram showing an example of the downlink path of this embodiment. FIG. 11 shows an example of the downlink path of the terminal 3-9 determined based on the upload path of the terminal 3-9 shown in FIG. 6 . In this way, in this embodiment, a plurality of downlink paths are set for each terminal 3 .

As mentioned above, in this embodiment, the line concentrating device 2 maintains p downlink paths, but when receiving more than p uplink communication control signals from one terminal 3, that is, from one terminal 3 to the line concentrating device 2 When there are more than p upload paths, the hub device 2 selects p upload paths according to the number of hops, communication quality, etc., and keeps the download path corresponding to the selected upload path as the download path information.

Moreover, when a terminal 3 newly joins the communication system after the path construction between the line concentrating device 2 and the terminal 3 is performed, the terminal 3 broadcasts a joining message. When each terminal 3 receives the join message, it sends a response message including the line hub device ID of the line hub device 2 corresponding to its own device and the minimum number of hops in the downlink path stored in the terminal table to the sender of the join message. The terminal 3 of the source adds the terminal ID of the own terminal to the join message and forwards it to the upload path, similarly to the above-mentioned upload communication control signal. The terminal that sends out the join message stores the terminal ID of the terminal 3 that is the source of each response message in the terminal table as the terminal ID of the next hop node in one of the upload paths, and stores it in the response message contained in the The value obtained by adding 1 to the hop count is used as the hop count of the upload path. In this way, the newly added terminal 3 can store the relevant information of the upload path in the terminal table. In addition, the line hub device 2 can store a plurality of downlink paths toward the newly added terminal 3 in the downlink path information similarly to the above-mentioned case of receiving the downlink communication control signal by receiving the joining message. Alternatively, when a terminal 3 newly joins the communication system, the newly added terminal 3 waits for the multi-point hopping construction signal sent by the surrounding terminals 3, and when receiving the multi-point hopping construction signal, sends an upload control signal or an upload communication signal .

Next, the downlink communication in the line hub device 2 of this embodiment will be described. When the central device 1 sends a signal including data destined for the terminal 3, it uses the line hub device information stored in the path information storage unit 13 to find the corresponding line hub device 2, and sends the signal to the terminal 3. to the obtained line concentrator 2.

When the hub device 2 receives a signal from the central device 1 to be sent to the terminal 3, it uses the downlink path information to copy the data included in the signal, and generates a plurality of signals respectively including the copied data. The hub device 2 sends a plurality of signals including the same data through a plurality of downlink paths respectively. For example, the hub device 2 continuously sends a plurality of signals through different downlink paths. Also, here is an example of continuously sending a plurality of signals containing the same data through different downlink paths, but it is also possible to transmit multiple signals containing the same data through different downlink paths at the same time. can be sent simultaneously.

FIG. 12 is a flow chart showing an example of the transmission procedure of the downstream signal in the line hub device 2 of this embodiment. As shown in FIG. 12, the communication control unit 23 of the line hub device 2 copies the data to be sent to the terminal 3, and initializes ns of a variable indicating the number of times of sending the same data to 0 (step S21). The communication control unit 23 selects a downlink path from a plurality of downlink paths (step S22). Specifically, the communication control unit 23 reads out a plurality of downlink routes corresponding to the destination terminal 3 from the downlink route information in the route information storage unit 24 , and selects one route from the read out downlink routes.

The communication control unit 23 sends the data toward the selected downlink path (step S23). Specifically, the communication control unit 23 adds information representing the selected downlink path to one of the copied data as a header, and stores the terminal ID of the destination terminal 3 in the header. destination, and send it to the terminal 3 of the next hop node under the selected downlink path via the first transceiver unit 21 . In this way, each data to be sent to the terminal 3 is transmitted by unicast. At this time, the communication control unit 23 adds the same serial number to the data copied from the same data. FIG. 13 is a diagram showing an example of the format of a downlink packet as a downlink signal in this embodiment. As shown in FIG. 13 , the downlink signal is composed of a header and a data part, and the data part stores the above-mentioned copied data. The header system contains destination information, message information and sequence number. The message information is information indicating the type of the transmitted signal, that is, the type of the message corresponding to the signal. The destination information in the header stores the identification information of the next node with the destination. Also, although the illustration is omitted, the header also stores information indicating the download path.

Return to the description of FIG. 12 . The communication control unit 23 increases the value of ns by 1 (step S24), and judges whether ns is smaller than the number of downlink paths, that is, p (step S25). When ns is smaller than the number of downlink paths (step S25, Yes), the processing from step S22 is repeated. In step S22 after the second time, the downlink path to send the downlink signal is selected from the downlink paths that have not sent the downlink signal. When ns is equal to or greater than the number of downlink paths (step S25, No), the communication control unit 23 ends the downlink signal transmission process.

Through the above processing, a plurality of downlink signals storing the same data are respectively sent through a plurality of downlink paths. In this way, the communication control unit 23 of the line hub device 2 of the present embodiment uses an uplink control signal which is an example of an uplink signal stored in an uplink signal transmitted from one of the plurality of terminals 3 to the line hub device 2 . The identification information of the passing terminal 3 determines a plurality of downlink paths towards the source terminal, and uses the determined downlink paths to transmit the same downlink data with the source terminal as the destination. In this way, even if there is a communication obstacle, a communication error, etc. in the downlink path, the downlink signal will still reach the destination terminal 3 through other downlink paths, which can improve reliability compared with the case of sending through one downlink path. Spend. Moreover, even if a communication failure occurs in the downlink path, if the downlink signal arrives at the terminal 3 through other downlink paths, no further transmission is necessary, so low-latency downlink communication can be realized.

Next, the reception processing of the downlink signal in the terminal 3 will be described. FIG. 14 is a flowchart showing an example of the reception process of the downlink signal in the terminal 3 of this embodiment. In the terminal 3 , when the transmitting and receiving unit 31 receives a signal, it passes the signal to the communication control unit 32 . The communication control unit 32 determines that the signal received from the transceiver unit 31 is a downlink signal when the destination of the signal received from the transceiver unit 31 is not the line hub device 2, and performs the processing shown in FIG. 14 . Here, when the destination of the signal received from the transceiver 31 is the hub device 2 , the communication control unit 32 transfers the signal to the upload route using the terminal table stored in the route information storage unit 33 .

As shown in FIG. 14, when receiving a downlink signal, the communication control unit 32 judges whether the destination is its own terminal (step S31). When the destination is the own terminal (step S31, Yes), the communication control unit 32 judges whether the same data has been received (step S32). As mentioned above, because the same data is attached with the same serial number, so the communication control unit 32 of the terminal 3 can judge that it has been received when the data with the same serial number as the serial number attached to the data received this time has been received. the same information. Here, the method of judging whether it is the same data as the received data is not limited thereto. For example, the terminal 3 may store data received in the past for a certain period of time and compare it with the stored data.

When not receiving the same data (step S32, No), the communication control unit 32 delivers the data to the control processing unit 34, and the control processing unit 34 performs data processing of the data (step S33), and ends the receiving process. When the same data has been received (step S32, Yes), the communication control unit 32 destroys the data received this time (step S34), and ends the receiving process. In this way, when the terminal 3 newly receives the downloaded data with the same serial number as the received downloaded data, it destroys the newly received downloaded data.

Also, when the destination is not the self-terminal (step S31, No), the communication control unit 32 transmits the data to the downlink path via the transceiver unit 31 according to the information of the downlink path attached to the received data The terminal 3 of the lower layer of a node (step S35), and ends the receiving process.

As mentioned above, the line concentrator 2 sends the same data to the terminal 3 using a plurality of downlink paths, but after sending the same data using a plurality of downlink paths, there is no response from the terminal 3 after a certain period of time. In case of a communication error, the transmission shown in Fig. 12 can be performed again for retransmission. That is, when the downlink data sent by using the multiple downlink paths all become communication errors, the downlink data can also be resent by using the multiple downlink paths. In addition, even if the downlink data is still a communication error during re-sending, the downlink data to be sent to the terminal 3 can also be sent by broadcasting. At this time, the terminal 3 other than the destination transfers the data received by broadcasting.

Here, in general, a check bit for performing a CRC check is added to a signal transmitted and received between nodes in order to enable error detection using a CRC (Cyclic Redundancy Code; Cyclic Redundancy Code). Generally speaking, the data that has been found to be an error by the CRC check is destroyed, but in this embodiment, as described above, the terminal 3 receives the same data multiple times because the same data is sent through multiple downlink paths. Therefore, the terminal 3 may not destroy the wrong data detected by the CRC, but temporarily keep it, and then perform statistical processing or error correction processing together with the data received later, so as to restore the correct data. That is to say, it is also possible to add a detection bit for error detection to the downlink data, and the terminal 3 uses the bit for detection to perform error detection of the downlink signal including the downlink data, and sends it to the downlink signal through error detection. When an error is detected in the downloaded data of the terminal 3, the downloaded data is kept, and the stored downloaded data corresponding to the same serial number is used to restore the downloaded data.

FIG. 15 is a flowchart showing an example of the reception processing sequence of the downlink signal including the restoration processing using CRC in this embodiment. As shown in FIG. 15 , when receiving a downlink signal, the communication control unit 32 performs error detection through CRC (step S41 ). The communication control unit 32 executes the above-mentioned step S31 when no error is detected from the header portion of the downlink signal through the error detection (step S42, No).

When step S31 is "Yes", it is judged whether there is an error in the data section (step S43). When there is an error in the data section (step S43, yes), temporarily save the data (step S44), and the communication control unit 32 is to judge whether there are more than a certain number of the same data temporarily stored (step S45) with respect to the data of the same serial number. When there are more than a certain number of temporarily saved identical data (step S45, Yes), the communication control unit 32 restores the correct data using the temporarily saved data (step S46). For example, as far as the bit value of the same position is concerned, among a plurality of temporarily stored data, only one value is a different first value, while the others are the same second value, the bit value is determined as the first binary value. After step S46, the processing of step S33 similar to that of FIG. 14 is performed.

When the same data that has been temporarily stored does not reach a certain number (step S45, No), the communication control unit 32 ends the receiving process. Moreover, when step S43 is "NO", the process of step S33 is performed. Moreover, when step S31 is NO, step S35 is performed similarly to FIG. 14 . When step S42 is "Yes", the communication control unit 32 destroys the data (step S47), and ends the receiving process.

Through the above processing, among the plurality of downlink signals that store the same data received by the terminal 3, even if a communication error occurs in the plurality of downlink signals, the data can still be temporarily saved first, and then the plurality of data can be used to restore the correct data.

As explained above, in this embodiment, the hub device 2 keeps and stores the downlink path information representing the information of the plurality of downlink paths, and sends a plurality of downlink signals storing the same data through the plurality of downlink paths respectively. In this way, even if there is a communication obstacle, a communication error, etc. in the downlink path, the downlink signal will still reach the destination terminal 3 through other downlink paths, which can improve reliability compared with the case of sending through one downlink path. Spend. Moreover, even if a communication failure occurs in the downlink path, if the downlink signal arrives at the terminal 3 through other downlink paths, no further transmission is necessary, so low-latency downlink communication can be realized.

Implementation type 2. Fig. 16 is a diagram showing a configuration example of a central device in Embodiment 2. FIG. 17 is a diagram showing a configuration example of a line concentrator in Embodiment 2. FIG. The communication system of this embodiment is equipped with the central device 1a shown in FIG. 16 instead of the central device 1 shown in FIG. Except for the line concentrating devices 2-1 and 2-2, the rest are the same as the communication system of the implementation type 1. Similar to Embodiment 1, the number of line concentrators 2a and the number of terminals 3 in this embodiment are not limited to the example shown in FIG. 1 . Components having the same functions as those in Embodiment 1 are denoted by the same symbols and redundant descriptions are omitted. Hereinafter, differences from Embodiment 1 will be mainly described.

In Embodiment 2, the line concentrating device 2a uses the uplink communication control signal sent from the terminal 3 to obtain the downlink path corresponding to the uplink path of each terminal in the same way as in Embodiment 1, and will indicate the The downlink path information of the uplink path is sent to the central device 1a. And, the central device 1a maintains a plurality of downlink paths towards the terminal 3 corresponding to one terminal 3, and when sending downlink data to be sent to the terminal 3, the central device 1a copies the data and separates them Sent with multiple downlink paths.

As shown in FIG. 16, the central device 1a is equipped with a communication control unit 12a instead of the communication control unit 12, and has a route information storage unit 13a instead of the route information storage unit 13. In addition, it is the same as the central device of Embodiment 1. 1 is the same.

As shown in FIG. 17, the line concentrating device 2a is equipped with a communication control unit 23a instead of the communication control unit 23, and has a route information storage unit 24a instead of the route information storage unit 24. In addition, it is the same as the line concentrating device of Embodiment 1. 2 is the same.

Next, the operation of route construction in this embodiment will be described. Step S1 to step S12 shown in FIG. 7 are performed in the same manner as in the first embodiment. When a certain period of time has elapsed since the transmission of the wireless multi-point hopping construction signal in step S2 and the uplink communication control signal is received from all the terminals 3, the communication control unit 23a of the hub device 2a will record the uplink communication control signal sent from each terminal 3. The downlink path information obtained from the signal is included in the terminal notification signal, and the terminal notification signal is sent to the central device 1 a through the second transceiver unit 22 .

When the communication control unit 12a of the central device 1a receives the terminal notification signal through the transceiver unit 11, it uses the upload path of each terminal 3 contained in the terminal notification signal to determine the download path of each terminal 3 with the opposite path of the upload path. route, and store it as the downlink route information in the route information storage unit 13a. FIG. 18 is a diagram showing an example of downlink route information in this embodiment. The downlink path information stores information indicating m downlink paths from the downlink path #1 to the downlink path #m for each terminal 3 . m is an integer of 2 or more, and is determined in advance. m may be changed by an input from an operator, an instruction from another device not shown, or the like. In this embodiment, the downlink path stored as downlink path information also includes the line hub device ID of the line hub device 2 a relaying the communication from the central device 1 a to the terminal 3 . For example, in the configuration example shown in FIG. 6 of Embodiment 1, when the central device 1 is replaced by the central device 1a, and the line concentrators 2-1 and 2-2 are replaced by the line concentrators 2a-1 and 2a-2 , the download path of the terminal 3-9 can be set as the opposite path of each of the upload paths 4-1 to 4-3. Therefore, the multiple downlink paths of the terminal 3-9 include the path via the line concentrator 2a-1 and the path via the line concentrator 2a-2.

Next, the sequence of sending the downlink signal including the downlink data to be sent to the terminal 3 will be described. In this embodiment, the central device 1a executes the processing shown in FIG. 12 . That is, the communication control unit 12a of the central device 1a copies the data to be sent to the terminal, and uses the downlink route information to implement the processing shown in FIG. 12 . At this time, as in Embodiment 1, the same serial number is added to the same data. Also, although the information representing the downlink path is added to each data, it is enough for the communication control unit 12a of the central device 1a to send the downlink signal to the line gathering device 2a corresponding to each downlink path, so the line gathering on the downlink path The hub device ID of the device 2a may not be included in the information indicating the downlink route added to each data. When the communication control unit 23a of the hub device 2a receives the downlink signal via the second transceiver unit 22, it sends the downlink signal to the next node according to the information indicating the downlink path stored in the downlink signal. The operation of each terminal 3 is the same as that of the first embodiment. Furthermore, in this embodiment, since a plurality of line concentrating devices correspond to one terminal 3, a plurality of line concentrating device IDs are stored corresponding to one terminal 3 in the line concentrating device information.

In this way, in this embodiment, the line hub device 2a sends the identification information of the terminal through which the upload communication control signal passes to the central device 1a as the downlink path information, and the central device 1a uses the downlink path information to determine a plurality of directions to send downlink paths of the source terminal, and use the determined plurality of downlink paths to respectively send the same downlink data with the source terminal as the destination. In this embodiment, since the plurality of downlink paths can be dispersed together with the line concentrator 2a, and the same data can be sent using the dispersed plurality of downlink paths, compared with the implementation type 1, the number of downlink paths can be improved. Independence of transmission path. In this way, even if there is a communication failure around a certain line concentrating device 2a, the download data to be sent to the terminal 3 will still reach the terminal 3 through other line concentrating devices 2a, so it is possible to achieve high reliability and low delay downloading. pass newsletter.

Furthermore, in this embodiment, the central device 1a manages a plurality of downlink paths of each terminal 3, but as far as the line collection device information is concerned, the central device 1a can also maintain a plurality of line collection devices corresponding to one terminal 3, and use The line concentrator manages the downstream path information lower than the line concentrator 2a. At this time, the same line concentrating device 2 as that in Embodiment 1 is used as the line concentrating device, and the central device 1a stores the plurality of line concentrating device IDs of the plurality of line concentrating devices 2 corresponding to each terminal 3 in the line concentrating device information instead of the plurality of each terminal 3 download path. Moreover, the communication control unit 12a of the central device 1a copies the downlink data to be sent to the terminal 3, and sends them to a plurality of line concentrating devices 2 respectively according to the line concentrating device information. That is, the line concentrator 2 sends to the central device 1a the information representing the terminal 3 to communicate with the central device 1a via the line concentrator 2, and the central device 1a uses the information received from the line concentrator 2 to communicate with the source terminal The corresponding two or more line concentrators 2 respectively transmit the same downlink data whose destination is the transmission source terminal. At this time, the same data is also sent to the terminal 3 via a plurality of hub devices 2 .

In addition, the communication system of this embodiment can also have the function of the communication system of Embodiment 1 to realize the actions of both parties.

The hardware configurations of the central device 1a and the line concentrator 2a of this embodiment are the same as those of the central device 1 and the line concentrator 2 of the first embodiment.

As mentioned above, in this embodiment, the same data is sent toward the terminal 3 through a plurality of downlink paths including downlink paths through different hub devices. Therefore, because the same effect as that of Embodiment 1 can be achieved, and the hub devices included in each downlink path can be dispersed, the probability of downlink data reaching the terminal 3 can be increased.

Implementation type 3. Next, the operation of Embodiment 3 will be described. The configuration of the communication system of this embodiment, and the configuration of the central device 1, the hub device 2, and the terminal 3 are the same as those of the embodiment 1. The operation of each device of this embodiment is the same as that of Embodiment 1 except that the method of sending the downlink signal described below is partly different. Components having the same functions as those in Embodiment 1 are assigned the same symbols and repeated descriptions are omitted. Hereinafter, differences from Embodiment 1 will be mainly described.

FIG. 19 is a flow chart showing an example of the sending sequence of the downlink signal including the downlink data in the hub device 2 of this embodiment. Steps S21 and S22 are the same as those in Embodiment 1. After step S22, the communication control unit 23 sends the same data multiple times toward the selected route (step S26). That is, the communication control unit 23 sends the same downlink data multiple times for the downlink path. Steps S24 and S25 are the same as those in Embodiment 1.

Also, in the above example, the same data is sent multiple times towards each downlink path without considering the number of downlink paths, but the terminal 3 shown in FIG. Action, and the action of implementation type 1 is performed for the terminal whose number of downlink paths is above the threshold value.

In the above example, the same data is sent multiple times to the downlink path by the hub device 2, but the central device 1a that manages the multiple downlink paths of the implementation type 2 can also send the same data multiple times to the downlink path in the same way. transmission path. In addition, the central device 1a described in the implementation type 2 manages information corresponding to a plurality of line concentrating devices 2a of a terminal 3. If the line concentrating device 2a manages a plurality of downlink paths, the same can also be done by the line concentrating device 2a. Send the same data multiple times to the download path.

As mentioned above, in this embodiment, the same data is sent to multiple downlink paths, and the same data is sent to multiple downlink paths continuously. Therefore, the same effect as that of Embodiment 1 can be achieved, and in the case of a temporary failure in the downlink path, if the communication failure recovers, the downlink data will reach the terminal 3, so the reliability can be further improved and reduce latency.

Implementation type 4. Next, the transmission method of the uplink communication control signal in Embodiment 4 will be described. The configuration of the communication system of this embodiment, and the configuration of the central device 1, the hub device 2, and the terminal 3 are the same as those of the embodiment 1. The operation of each device of this embodiment is the same as that of Embodiment 1 except for the operations described below. Components having the same functions as those in Embodiment 1 are given the same reference numerals and redundant descriptions are omitted. Hereinafter, differences from Embodiment 1 will be mainly described.

In the implementation type 1, the terminal 3 sends an upload communication control signal every time it receives a wireless multi-point hopping construction signal. In this embodiment, each terminal 3 does not immediately send an upload communication control signal even if it receives the wireless multi-point hopping construction signal, but uses the wireless multi-point hopping construction signal received within a certain period of time to select a plurality of upload paths, And send the upload communication control signal to the next node in the upload path corresponding to the selected upload path.

For example, the communication control unit 32 of the terminal 3 selects k upload paths by using the signal strength of the wireless multi-point hopping configuration signal received from other terminals 3 or signals other than the wireless multi-point hopping configuration signal from other terminals 3 . Specifically, the communication control unit 32 calculates an average value such as a moving average or an interval average of signal strengths of signals received by each terminal 3 for signals received from other terminals 3, and holds the calculated average value as each Signal strength meter for Terminal 3. FIG. 20 is a diagram showing an example of a signal strength table held by the terminal 3-9 of this embodiment. As shown in FIG. 20 , according to the terminal 3 of the transmission source of each signal, that is, according to the next node in each upload path, the signal strength is maintained as a signal strength table. The communication control unit 32 of the terminal 3-9 uses the signal strength table to select k upload paths in order of signal strength from high to low, and maintains information representing the selected k upload paths as a terminal table, and uses the selected The k upload paths are used to send the upload communication control signal. In addition, the signals used in the communication upload path are not limited to the upload communication control signals, and can also be other upload signals. That is, the terminal 3 uses the signal strengths of signals received from other terminals 3 to select k upload paths of the first number of upload paths, and uses the k upload paths to send the upload signal.

The communication control unit 32 of the terminal 3 can also send an upload communication control signal or other upload signals by round robin for the selected k upload paths. Alternatively, the communication control unit 32 may also send an upload communication control signal or other upload signals through a weighted round robin for the selected k upload paths. That is, the communication control unit 32 may also select an upload path according to a weighted cycle based on signal strength, and use the selected upload path to send the upload signal.

The k uplink communication control signals are added with the terminal IDs of the terminals 3 that have passed through the respective uplink paths as in the first embodiment. Thereby, the line concentrating device 2 can obtain k uploading paths according to each terminal 3, and select p uploading paths of the second number of uploading paths from the k uploading paths, and transfer one of the selected p uploading paths The opposite path is used as the downlink path, and is kept as the downlink path information. Here, the line concentrator 2 may also use the downlink path corresponding to all the acquired uplink paths as the downlink path, and keep it as downlink path information. That is, p and k can also be equal.

The communication control unit 23 of the hub device 2 selects p uploading paths of the second number of uploading paths from the k uploading paths according to the path cost value of each uploading path. The path cost value can be calculated using, for example, the signal strength of each terminal 3 and the number of hops of each path. For example, it is calculated by the weighted sum of the reciprocal of the signal strength and the number of hops. The signal strength is, for example, a moving average or an interval average of the signal strength of the signal received by the hub device 2 . Alternatively, each terminal 3 may add the signal strength of the above-mentioned signal strength table to the signal strength corresponding to each upload path, and use the hub device 2 to grasp the signal strength of each link of the upload path, and then according to each link The signal strength and hops of the nodes are used to calculate the path cost value. The communication control unit 23 selects n upload paths from the k upload paths in order of path cost values from low to high, and uses the n upload paths to determine n downlink paths. In this way, the hub device 2 calculates the path cost value according to each upload path of the terminal 3 according to the signal strength of the upload signal and the corresponding hop number, and determines the second number of downlink paths according to the path cost value.

Furthermore, since the communication status may change, the downlink path can also be updated periodically. Furthermore, the so-called update here also includes the situation that the downlink path has not changed even though the process for updating has been performed. For example, the hub device 2 updates the downlink path according to the past signal strength and the like as described below. For example, the hub device 2 collects relevant information of the upload path by periodically sending wireless multi-point hop building signals and the like. When the period of collecting the data of the upload path is set as the first period, the communication control unit 23 first memorizes the number of hops and the signal strength related to the upload path received between the first period, and will use the stored hop number and The path cost values calculated by the signal strength are weighted averaged, and then the p downlink paths are determined by using the average value obtained by the weighted average. The first period may be 24 hours, 30 days, 1 month, or a period other than these. Alternatively, the collected information of the first period can also be divided into data of each second period shorter than the first period, and the average value of the path cost is calculated according to the number of hops and signal strength of each second period, and the The average values of each second period are weighted average, and then the n downlink paths are determined by using the average weighted average. For example, the weighted average of every t hours can be obtained from the collected data of 24 hours, the weighted average of every d days can be obtained from the collected data of 30 days, and the weighted average of every time d can be obtained from the collected data of several months. Weighted average for one month. At this time, in order to reflect more latest information in the plurality of second periods, when weighted average is performed, for example, the latest information decreases the weight value. That is, the weight in the weighted average is determined such that the more the path cost value calculated based on the latest uploaded signal is, the smaller the value is.

In addition, when the line concentrator 2 has obtained relevant information of more than p+1 upload routes from the terminal 3, it extracts routes passing through the same terminal 3 from among these upload routes, and calculates the route cost of the extracted routes Upload paths with higher values are excluded from selection. That is to say, when the hub device 2 receives an upload signal corresponding to an upload path whose number is greater than the second number, it determines the second number of downlink paths as giving priority to the downlink paths that do not overlap the terminals 3 to pass through. . Thereby, the plurality of downlink paths can be prevented from passing through the repeated terminals 3 as much as possible, that is, the plurality of downlink paths can be dispersed, and the reliability can be improved. Furthermore, each action of this embodiment can also be applied to Embodiment 2.

Furthermore, this implementation mode can also be combined with implementation mode 2 or implementation mode 3. In addition, this embodiment can also be combined with Embodiment 2 and Embodiment 3.

As mentioned above, in this embodiment, the terminal 3 selects a plurality of upload paths according to the path cost value, and uses the selected upload path to send the upload communication control signal. Thereby, the same effect as that of Embodiment 1 can be achieved, and the consumption of the communication band can be suppressed by not passing through the upload path with a high path cost value. Moreover, since the line hub device 2 selects the downlink path according to the average path cost, it can stably select a path with a good communication state without being affected by the state of the temporary path. Also, since a plurality of downlink paths are distributed and selected, reliability can be improved.

Implementation type 5. Next, the operation of Embodiment 5 will be described. The configuration of the communication system of this embodiment, and the configuration of the central device 1, the hub device 2, and the terminal 3 are the same as those of the embodiment 1. The operation of each device of this embodiment is the same as that of Embodiment 1 except that the method of sending the downlink signal described below is partly different. Components having the same functions as those in Embodiment 1 are given the same reference numerals and redundant descriptions are omitted. Hereinafter, differences from Embodiment 1 will be mainly described.

In this embodiment, when the downlink data that requires reliability is to be sent, as described below, the broadcast transfer is utilized to increase the arrival rate of the terminal 3 toward the destination.

The communication control unit 23 of the line concentrator 2 transmits the downlink data by unicast in the same way as in the first embodiment for the route whose hop count is 1 until reaching the destination terminal 3 . When the number of hops until reaching the destination terminal 3 is 2 or more, the communication control unit 23 of the hub device transmits the downlink data by broadcasting at least a part of the downlink path when transmitting the downlink data.

Specifically, for example, the communication control unit 23 of the line hub device 2 adds to the downlink data: information indicating the corresponding downlink path; The information to be forwarded by broadcasting and the limited number of times of forwarding when forwarding by broadcasting. The limited number of forwarding times is the number minus 1 from the number of hops from the corresponding terminal 3 to the destination of the downlinked data. When the terminal 3 receives the downlink data sent by broadcast with the transfer limit number set to 1, it then forwards the downlink data by unicast. When the communication control unit 32 of each terminal 3 is instructed to transfer by broadcast using information indicating the downlink route attached to the downlink data and information indicating whether to transfer by broadcast or by unicast , set the indicated transfer limit times and transfer by broadcasting. These downloaded materials are all appended with the same serial number. For example, the communication control unit 23 of the line hub device 2 sets the above information to be forwarded by unicast to the terminal 3 whose hop count of the terminal 3 reaching the destination is greater than j of the threshold value, and for the terminal 3 reaching the destination Terminals 3 whose number of hops are equal to or less than the threshold value transfer by broadcast.

FIG. 21 is a diagram showing an example of a downlink signal transmission method in this embodiment. In the example shown in FIG. 21 , j of the threshold value is 3, and the destination of the downlink signal storing the downlink data is the terminal 3 - 9 . In FIG. 21 , "B" indicates transmission by broadcast, and "U" indicates transmission by unicast. In the example shown in FIG. 21, since the nodes whose hop count becomes 3 when reaching the terminal 3-9 are the line concentrators 2-1 and 2-2, the transfer limit times in the line concentrators 2-1 and 2-2 are set to 2. Send the downlink signal including the downlink data to be sent to the terminal 3 by broadcasting. The terminal 3-1, 3-2 which received the signal transmitted by broadcast from the line hub device 2-1, 2-2, the number of hops to reach the terminal 3-9 is 2 and j or less, and from the line hub device 2 -1, 2-2 The number of forwarding limit of the received downlink signal is 2, so it is changed to subtract 1 from the number of forwarding limit, and the downlink signal is sent by broadcasting. When the terminals 3-4 and 3-5 receive the downlink signals sent by broadcasting from the terminals 3-1 and 3-2, since the number of forwarding limit of the received downlink signals is 1, the single The broadcast sends the downlink signal to the terminal 3-9.

Furthermore, this embodiment can also be combined with one or more of the embodiments 2, 3, and 4. As in Embodiment 2, when the central device 1a determines the downlink path, the communication control unit 12a of the central device 1a can set whether to use the above-mentioned hop count as broadcast information.

Thus, in this embodiment, the arrival rate of downlink data to the terminal 3 can be improved by performing broadcast transfer on at least a part of the downlink path. In addition, the terminal 3 that transfers by broadcasting can be limited in response to the number of hops to reach the destination, the number of restricted transfers by broadcasting, etc., and not all terminals 3 perform transfer by broadcasting. This suppresses the communication frequency band used.

The configurations shown in the above embodiments are merely examples, and they can be combined with other known techniques, or can be combined with each other, and a part of the configuration can be omitted or changed without departing from the gist.

1,1a: central device 2,2a,2-1,2-2: hub device 3,3-1~3-12: terminal 4-1~4-3: Upload path 11,31: Sending and receiving department 12, 12a, 23, 23a, 32: Communication Control Department 13,13a,24,24a,33: path information memory 14,25,34: control processing unit 21: The first sending and receiving department 22: The second transceiver department 100: control circuit 101: Processor 102: Memory S1,S2,S3,S4,S5,S6,S7,S8,S9,S10,S11,S12,S13,S14,S21,S22,S23,S24,S25,S26,S31,S32,S33,S34,S35, S41, S42, S43, S44, S45, S46, S47: steps B: Transmission by broadcasting U: Transmission by unicast

FIG. 1 is a diagram showing a configuration example of a communication system of Embodiment 1. As shown in FIG. FIG. 2 is a diagram showing a configuration example of a central device in Embodiment 1. FIG. FIG. 3 is a diagram showing a configuration example of a line concentrator in Embodiment 1. FIG. FIG. 4 is a diagram showing a configuration example of a terminal in Embodiment 1. FIG. FIG. 5 is a diagram showing an example of a control circuit of Embodiment 1. FIG. FIG. 6 is a diagram showing an example of an upload route in Embodiment 1. FIG. FIG. 7 is a sequence diagram showing an example of the route construction procedure in the communication system of Embodiment 1. FIG. FIG. 8 is a diagram showing an example of a terminal table in Embodiment 1. FIG. FIG. 9 is a diagram showing an example of downlink route information in Embodiment 1. FIG. FIG. 10 is a diagram showing an example of line concentrator information in Embodiment 1. FIG. FIG. 11 is a diagram showing an example of a downlink path in Embodiment 1. FIG. FIG. 12 is a flow chart showing an example of the transmission procedure of the downstream signal in the line hub device of Embodiment 1. FIG. FIG. 13 is a diagram showing an example of the format of a downlink packet as a downlink signal in Embodiment 1. FIG. FIG. 14 is a flowchart showing an example of downlink signal reception processing in the terminal of Embodiment 1. FIG. Fig. 15 is a flowchart showing an example of the reception processing sequence of the downlink signal including the restoration processing using CRC in Embodiment 1. Fig. 16 is a diagram showing a configuration example of a central device in Embodiment 2. FIG. 17 is a diagram showing a configuration example of a line concentrator in Embodiment 2. FIG. FIG. 18 is a diagram showing an example of downlink route information in Embodiment 2. FIG. FIG. 19 is a flow chart showing an example of the transmission sequence of the downlink signal including the downlink data in the hub device according to the third embodiment. FIG. 20 is a diagram showing an example of a signal strength table held by a terminal in Embodiment 4. FIG. FIG. 21 is a diagram showing an example of a downlink signal transmission method in Embodiment 5. FIG.

2-1: Harnessing device

3-1,3-4: terminal

S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14: steps

Claims (43)

A communication system that can constitute a wireless multi-point hopping network, which includes more than one line-collecting device, and a plurality of terminals that send uploaded data to the aforementioned line-collecting device; The communication system uses the identification information of the aforementioned terminal through which the aforementioned uploaded signal is stored in the uploaded signal transmitted from one of the aforementioned plurality of terminals to the aforementioned line hub device, to determine a plurality of terminals towards the aforementioned source terminal. downlink path, and use the determined plurality of downlink paths to respectively send the same downlink data with the aforementioned source terminal as the destination. The communication system as described in Claim 1, wherein the aforementioned line hub device uses the identification information of the aforementioned terminal stored in the aforementioned upload signal to determine a plurality of downlink paths towards the aforementioned source terminal, and uses the determined plurality of The aforementioned downlink paths respectively send the same downlink data whose destination is the aforementioned sending source terminal. The communication system as described in Claim 2 is equipped with a plurality of the above-mentioned line gathering devices; And further have a central device for communicating with a plurality of the aforementioned line hub devices; The aforementioned line hub device transmits to the aforementioned central device information indicating the aforementioned terminal communicating with the aforementioned central device through the aforementioned line hub device; The aforementioned central device uses the aforementioned information to respectively send the same downlink data with the aforementioned sending source terminal as a destination to two or more aforementioned line hub devices corresponding to the aforementioned sending source terminal. The communication system as described in claim 1 is equipped with a plurality of the above-mentioned line gathering devices; And further have a central device for communicating with a plurality of the aforementioned line hub devices; The aforementioned hub device sends the identification information of the aforementioned terminal stored in the aforementioned upload signal as upload path information to the aforementioned central device; The aforementioned central device uses the aforementioned upload path information to determine a plurality of downlink paths towards the source terminal, and uses the determined plurality of downlink paths to respectively send the same downlink data with the aforementioned source terminal as a destination. The communication system as described in any one of Claims 1 to 4 is to send the same downlink data with the aforementioned source terminal as the destination to one aforementioned downlink path multiple times. In the communication system described in any one of Claims 1 to 4, the same serial number is added to the same downlinked data whose destination is the aforementioned sending source terminal. In the communication system described in claim 5, the same serial number is added to the same downlinked data whose destination is the aforementioned sending source terminal. The communication system as described in any one of claims 1 to 4, wherein, when the aforementioned terminal newly receives the downloaded data with the same serial number as the received downloaded data, it destroys the newly received aforementioned downloaded data . The communication system as described in Claim 5, wherein, when the aforementioned terminal newly receives the downloaded data with the same sequence number as the received downloaded data, it destroys the newly received aforementioned downloaded data. The communication system as described in Claim 6, wherein, when the aforementioned terminal newly receives the downloaded data with the same sequence number as the received downloaded data, it destroys the newly received aforementioned downloaded data. The communication system as described in Claim 7, wherein, when the aforementioned terminal newly receives the downloaded data with the same serial number as the received downloaded data, it destroys the newly received aforementioned downloaded data. The communication system as described in claim 1 is to add detection bits for error detection to the aforementioned downloaded data; The aforementioned terminal uses the bit for detection to perform error detection of the downlink signal including the aforementioned downlink data, and when the aforementioned downlink data sent to the terminal is detected to have an error through the aforementioned error detection, the aforementioned downlink data is kept, And using the stored plurality of the aforementioned downloaded data corresponding to the same serial number to restore the aforementioned downloaded data. The communication system according to claim 1, wherein the source terminal uses the signal strength of signals received from other terminals to select a first number of upload paths, and uses the first number of upload paths to send the aforementioned upload signal. The communication system according to claim 2, wherein the source terminal uses the signal strength of signals received from other terminals to select the first number of upload paths, and uses the first number of upload paths to send the aforementioned upload signal. The communication system according to claim 3, wherein the source terminal uses the signal strength of signals received from other terminals to select the upload path of the first number, and uses the upload path of the first number to send the aforementioned upload signal. The communication system according to claim 4, wherein the source terminal uses the signal strength of signals received from other terminals to select the upload path of the first number, and uses the upload path of the first number to send the aforementioned upload signal. The communication system according to claim 5, wherein the source terminal uses the signal strength of signals received from other terminals to select the upload path of the first number, and uses the upload path of the first number to send the aforementioned upload signal. The communication system according to claim 6, wherein the source terminal uses the signal strength of signals received from other terminals to select the upload path of the first number, and uses the upload path of the first number to send the aforementioned upload signal. The communication system according to claim 7, wherein the source terminal uses the signal strength of signals received from other terminals to select the first number of upload paths, and uses the first number of upload paths to send the aforementioned upload signal. The communication system according to claim 8, wherein the source terminal uses the signal strength of signals received from other terminals to select the first number of upload paths, and uses the first number of upload paths to send the aforementioned upload signal. The communication system according to claim 9, wherein the source terminal uses the signal strength of signals received from other terminals to select the first number of upload paths, and uses the first number of upload paths to send the aforementioned upload signal. The communication system according to claim 10, wherein the source terminal uses the signal strength of signals received from the other terminals to select the upload path of the first number, and uses the upload path of the first number to send the aforementioned upload signal. The communication system according to claim 11, wherein the source terminal uses the signal strength of signals received from the other terminals to select the upload path of the first number, and uses the upload path of the first number to send the aforementioned upload signal. The communication system according to claim 12, wherein the source terminal uses the signal strength of signals received from other terminals to select the first number of upload paths, and uses the first number of upload paths to send the aforementioned upload signal. The communication system according to any one of claims 13 to 24, wherein the terminal selects an upload path according to a weighted cycle based on the signal strength, and uses the selected upload path to send the upload signal. The communication system as described in any one of claims 13 to 24, uses the upload signal of the first number sent from the aforementioned sending source terminal to determine the downlink path of the second number as the transmission path for the aforementioned sending The download path for the source terminal to send the download data. The communication system as described in claim 25 uses the upload signal of the first number sent from the source terminal to determine the downlink path of the second number as a way to send downlink data to the source terminal download path. The communication system as described in claim 26 calculates the path cost value based on the signal strength of the aforementioned uploaded signal and the corresponding number of hops according to each uploaded path indicated by the identification information of the aforementioned terminal through which the aforementioned uploaded signal passes, And the downlink path of the aforementioned second number is determined according to the aforementioned path cost value. The communication system as described in claim 27 calculates the path cost value based on the signal strength of the aforementioned uploaded signal and the corresponding number of hops according to each uploaded path indicated by the identification information of the aforementioned terminal through which the aforementioned uploaded signal passes, And the downlink path of the aforementioned second number is determined according to the aforementioned path cost value. The communication system as described in claim 28 is to carry out weighted average of the aforementioned path cost values calculated based on the aforementioned upload signals received during the first period, and determine the aforementioned second based on the average value obtained by the weighted average. The download path of the two numbers. In the communication system as described in claim 29, the aforementioned path cost values calculated based on the aforementioned upload signals received during the first period are weighted and averaged, and the aforementioned second is determined based on the average value obtained by the weighted average. The download path of the two numbers. The communication system as described in Claim 30, wherein the weight in the weighted average is determined to be such that the value of the path cost calculated based on the latest uploaded signal becomes smaller. The communication system as described in claim 31, wherein the weight in the weighted average is determined such that the value of the path cost calculated based on the latest uploaded signal becomes smaller. The communication system as described in claim 28 is related to the aforementioned sending source terminal, when receiving the aforementioned upload signal corresponding to the number of upload paths greater than the aforementioned second number, the aforementioned second number of downlink paths is determined as Priority is given to the downlink path through which the aforementioned terminals do not overlap. In the communication system according to any one of claims 1 to 4, 12 to 24, when sending the downlink data, the downlink data is sent by broadcasting on at least a part of the downlink path. The communication system as described in claim item 35 is to add to the aforementioned downlink data: information indicating the corresponding aforementioned downlink path; Information to be retransmitted by broadcast and the number of retransmissions when retransmitted by broadcast; The number of limited forwarding times is the number of hops from the corresponding terminal to the destination of the downloaded data minus 1; The aforementioned information is set to be forwarded by unicast to the aforementioned terminals whose hop count to the destination is greater than a threshold value, and to be forwarded by broadcast to the terminals whose hop count to the destination is below the threshold value; The aforementioned terminal transmits the aforementioned downlinked data by unicast when receiving the aforementioned downlinked data sent by broadcast with the aforementioned transfer limit times set to 1. The communication system described in any one of claims 1 to 4, 12 to 24 is to use the plurality of the aforementioned downlink paths when the aforementioned downlink data sent by using the plurality of the aforementioned downlink paths all become communication errors The resending of the aforementioned downloading data is performed, and when the aforementioned downloading data still becomes a communication error even during the aforementioned resending, the aforementioned downloading data is sent by broadcasting. The communication system according to any one of Claims 1 to 4, 12 to 24, wherein the aforementioned uploaded data are measurement data. A line gathering device is a line gathering device in a communication system, the communication system can constitute a wireless multi-point hopping network, and includes more than one line gathering device, and a plurality of terminals for sending and uploading data to the aforementioned line gathering device, the line gathering device has : The transceiver unit is configured to receive an upload signal sent from a source terminal of one of the plurality of terminals to the hub device; and The communication control unit uses the identification information of the terminal through which the uploaded signal is stored in the uploaded signal to determine a plurality of downlink paths toward the source terminal, and uses the determined plurality of downlink paths, The same downlink data whose destination is the aforementioned transmission source terminal are respectively transmitted. A central device is a central device in a communication system. The communication system includes a wireless multi-point hopping network. The wireless multi-point hopping network is formed by a plurality of line-collecting devices and a plurality of terminals that send uploaded data to the aforementioned line-collecting device. Composition, the central device in the communication system communicates with the aforementioned plurality of hub devices, and the central device has: The transmitting and receiving unit is configured to receive, from the aforementioned line hub device, the identification information of the aforementioned terminal through which the aforementioned upload signal is included in the upload signal sent from one of the aforementioned plurality of terminals to the aforementioned line hub device, as a downlink routing information; and The communication control unit determines a plurality of downlink routes toward the source terminal using the downlink route information, and transmits the same downlink route to the source terminal using the determined plurality of downlink routes, respectively. Pass information. A terminal is a terminal in a communication system, the communication system can constitute a wireless multi-point hopping network, and includes more than one line gathering device, and a plurality of terminals for sending and uploading data to the aforementioned line gathering device, and the communication system is used from The identification information of the aforementioned terminal through which the aforementioned upload signal is stored in the upload signal sent from one of the aforementioned plurality of terminals to the hub device determines a plurality of downlink paths towards the aforementioned source terminal, and uses Sending the same downlink data with the aforementioned sending source terminal as the destination for the plurality of determined downlink paths respectively; The terminal receives the same downlink data from a plurality of downlink paths, and destroys the newly received downlink data when it receives the same downlink data as the previously received downlink data. A communication method is a communication method in a communication system. The communication system can constitute a wireless multi-point hopping network, and includes more than one line gathering device, and a plurality of terminals that send and upload data to the aforementioned line gathering device. The communication method includes Follow these steps: Determining a plurality of downlink paths toward the source terminal by using the identification information of the terminal through which the uplink signal is stored in the uplink signal transmitted from one of the plurality of terminals to the hub device. steps; and The step of sending the same downlink data with the aforementioned sending source terminal as the destination respectively by using the determined plurality of the aforementioned downlink paths. A recording medium, which is recorded with a program that causes a communication system to execute the following steps. The communication system can constitute a wireless multi-point hopping network, and includes more than one line gathering device, and a plurality of terminals that send uploaded data to the aforementioned line gathering device, the aforementioned The steps include: Determining a plurality of downlink paths toward the source terminal by using the identification information of the terminal through which the uplink signal is stored in the uplink signal sent from one of the plurality of terminals to the hub device. steps; and The step of sending the same downlink data with the aforementioned sending source terminal as the destination respectively by using the determined plurality of the aforementioned downlink paths.

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