JP2015188140A - Node device, gateway device, sensor network system and data transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a node device that achieve a sensor network having high reliability.SOLUTION: A node device operates as a transfer node in a sensor network system having a sensor node, a collection server for collecting sensor data, a transfer node for transferring the sensor data and a gateway node connected to the collection server. When receiving sensor data which are pre-instructed from the gateway node to be subjected to transfer processing by the node device itself, the node device transfers the received sensor data. When receiving sensor data which are pre-instructed from the gateway node to be subjected to transfer processing by a node device other than the node device concerned, the node device concerned holds the sensor data, and when receiving a transmission request of sensor data from the gateway node, the node device concerned transmits the sensor data to the gateway node if the node device concerned holds the requested sensor data.

Description

  The present invention relates to a sensor network that transmits and receives sensor data, and more particularly to a node device, a gateway device, a sensor network system, and a data transfer method.

  In building and residential air-conditioning lighting management, crime prevention / disaster prevention applications, farm cultivation management, etc., it is more efficient to collect a variety of sensors and collect various data to grasp the state of the environment. Sensor networks that implement detailed environmental management and control are being put into practical use. Each node constituting the sensor network transmits and receives data by wireless communication.

  In sensor networks, it is necessary to construct a network that enables data collection by installing a large number of sensors in a variety of environments. In many cases, energy sources such as solar cells and small batteries are used as power sources. A wireless sensor node having a small wireless device is used. In addition, in order to expand the application area and extend the service life, further downsizing of the apparatus, reduction of power consumption such as low output of wireless communication and intermittent activation are being promoted.

  As a typical network technology applied to a sensor network, there is a Zigbee (registered trademark) technology. A sensor network is composed of wireless sensor nodes that are desired to be smaller and consume less power, and wireless relay nodes that have communication capabilities and information processing capabilities including relay functions. Multiple wireless sensor nodes can be combined into a single wireless relay node. The gateway is connected in a star shape, the plurality of wireless relay nodes are connected in a tree shape or a mesh shape, and a certain wireless relay node is connected to a server that collects sensor data.

  In such a sensor network, low power wireless technology is used as a wireless transmission path between the wireless sensor node and the wireless relay node, and between the wireless relay nodes. Therefore, errors due to interference and failures from other systems in the wireless transmission path. May occur, and a retransmission function may be required in collecting sensor data. However, a wireless sensor node that detects and transmits sensor data wirelessly may not have a sensor data holding function or a retransmission function in order to reduce power consumption. In this case, it is possible to perform retransmission control of sensor data at a wireless relay node that relays sensor data (see, for example, Patent Document 1).

JP 2011-244045 A

  In the communication system described in Patent Document 1, a communication unit (relay node) and a gateway that relay meter reading data (sensor data) transmitted to a business server that collects meter reading data (sensor data) perform relay processing. At that time, the relayed data is retained. When the business server fails to receive the meter reading data due to a communication failure or the like, it requests the meter reading data transmission unit (data transmission source node) to retransmit the meter reading data, and relays this request. When the business server holds the meter reading data requested to be retransmitted, the relay node resends the meter reading data on behalf of the data transmission source node.

  However, when sensor data is lost in a sensor network in which the communication path between the gateway device and each node is predetermined (fixed) as disclosed in Patent Document 1, the sensor node (data transmission) When sensor data sent wirelessly from the original node) arrives at the relay node, an error that cannot be corrected has occurred, and when an error that cannot be corrected has occurred in the wireless communication path from the relay node to the gateway There is. In either case, this is due to the sudden occurrence of failures such as temporary noise and interference from other systems in the wireless transmission path.

  Therefore, even if a request for retransmission is made to the relay node before such a temporary failure is resolved, there is a possibility that the retransmission request itself will not arrive due to the failure or the retransmitted sensor data will not reach due to the failure. large. In addition, when the relay node requested to retransmit the sensor data transmitted from the sensor node cannot be received, the sensor data itself requested to be retransmitted even if the retransmission request and the response can be normally communicated. Therefore, the sensor data cannot be retransmitted. As described above, the conventional sensor network has a problem that the retransmission of the sensor data may not be successful.

  The present invention has been made in view of the above, and an object thereof is to obtain a node device, a gateway device, a sensor network system, and a data transfer method that realize a highly reliable sensor network.

  In order to solve the above-described problems and achieve the object, the present invention includes a sensor node, a collection server that collects sensor data from the sensor node, and a transfer node that transfers the sensor data to the collection server. A node device that forms a sensor network together with the sensor node and the transfer node, and operates as the transfer node in a sensor network system including the collection server and a gateway node that connects the sensor network, When receiving sensor data instructed in advance from the gateway node to take charge of the transfer process, the data transfer means for transferring the received sensor data and the gateway node to take charge of the transfer process by a node device other than itself Sensor data specified in advance Holding means for holding the received sensor data when receiving the sensor data, and if the holding means holds the requested sensor data when the sensor data transmission request is received from the gateway node, the gateway And a data transmission means for transmitting to the node.

  According to the present invention, it is possible to increase the success rate of retransmission of sensor data, and to achieve an effect of realizing a highly reliable sensor network system.

FIG. 1 is a diagram showing a configuration example of a sensor network system according to the present invention. FIG. 2 is a diagram illustrating a configuration example of a gateway node. FIG. 3 is a diagram illustrating a configuration example of a sensor node accommodation table held by the gateway node. FIG. 4 is a diagram illustrating a configuration example of the forwarding node. FIG. 5 is a diagram illustrating a configuration example of a sensor node accommodation table held by the forwarding node. FIG. 6 is a diagram illustrating a configuration example of a sensor node. FIG. 7 is a diagram showing a basic operation of each device in the sensor network system having the configuration shown in FIG. FIG. 8 is a sequence diagram showing an example of operation when a sensor node is newly installed. FIG. 9 is a sequence diagram illustrating an example of an operation in which a registered sensor node transmits sensor data. FIG. 10 is a diagram showing an outline of an operation for retransmitting sensor data in the sensor network system having the configuration shown in FIG. FIG. 11 is a sequence diagram corresponding to the operation shown in FIG. FIG. 12 is a diagram illustrating the operation of each device in the sensor network system according to the third embodiment. FIG. 13 is a diagram illustrating the operation of each device in the sensor network system according to the third embodiment.

  Embodiments of a node device, a gateway device, a sensor network system, and a data transfer method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a sensor network system according to the present invention. The sensor network system includes a collection server 1, a gateway node (GW node) 2, transfer nodes 3A to 3C, and sensor nodes 4a to 4c. The transfer nodes 3A and 3B are located in the signal reachable range 5a of the sensor node 4a, and wireless communication with the sensor node 4a is possible. Similarly, the transfer nodes 3B and 3C located in the signal reachable range 5b of the sensor node 4b can wirelessly communicate with the sensor node 4b. The transfer node 3C located in the signal reachable range 5c of the sensor node 4c can wirelessly communicate with the sensor node 4c.

  Note that the number of transfer nodes and the number of sensor nodes constituting the sensor network system are not limited to the numbers shown in FIG. In the following description, when a configuration and operation common to the transfer nodes 3A to 3C are described, these are collectively referred to as the transfer node 3. Similarly, when a configuration or operation common to the sensor nodes 4a to 4c is described, these are collectively referred to as a sensor node 4.

  In the sensor network system, the sensor node 4 transmits the detected sensor data to the transfer node 3 wirelessly. The transfer node 3 receives the sensor data transmitted from the sensor node 4 and wirelessly transfers it to the GW node 2 that is a higher-level device. The GW node 2 receives the sensor data transferred from the transfer node 3 and transfers it to the collection server 1 and manages the network configuration of the sensor network formed by the sensor node 4 and the transfer node 3. The collection server 1 collects and analyzes sensor data detected by each sensor node 4. The connection form between the GW node 2 and each forwarding node 3 is not specified. A connection form in which the GW node 2 and the forwarding node 3 communicate via another node may be used.

  FIG. 2 is a diagram illustrating a configuration example of the GW node 2. The GW node 2 includes a server interface unit 21 that transmits sensor data to the collection server 1, a sensor data reception unit 22 that receives sensor data transmitted by the transfer node 3, and a transmission unit that transmits a transmission request to the transfer node 3. 23, a sensor node accommodation management unit 24 that manages the correspondence between the transfer node 3 and the sensor node 4, and a sensor node accommodation table 25 that holds the correspondence between the transfer node 3 and the sensor node 4.

  FIG. 3 is a diagram illustrating a configuration example of the sensor node accommodation table 25 held by the GW node 2. As shown in the figure, in the sensor node accommodation table 25, sensor node identifiers, identifiers and reception levels of accommodation designated transfer nodes, identifiers and reception levels of retransmittable transfer nodes, and sensor data reception status are registered. Yes. That is, information (identifier, reception level) of the accommodation designation transfer node, information (identifier, reception level) of the retransmittable transfer node, and sensor data reception status are registered in association with the sensor node identifier.

  In the sensor node identifier, identifiers of all sensor nodes 4 forming the sensor network are registered.

  The accommodation designation transfer node is information of the transfer node 3 accommodating each sensor node 4 registered in the sensor node identifier, and the identifier of the transfer node 3 operating as the accommodation designation transfer node is registered in the identifier. . In the reception level, the level of a signal received from the sensor node 4 accommodated by the transfer node 3 registered as the accommodation designation transfer node is registered. When the accommodation designation transfer node receives sensor data from the accommodated sensor node 4, the accommodation designation transfer node transfers the data to the GW node 2. The sensor node accommodation table 25 shown in FIG. 3 indicates that, for example, the sensor node 4a is accommodated in the transfer node 3A, and the transfer node 3A transfers the sensor data transmitted by the sensor node 4a. Further, the level of the signal received by the forwarding node 3A from the sensor node 4a is 80. Accordingly, when receiving the sensor data from the sensor node 4a, the transfer node 3A transfers the data to the GW node 2.

  The retransmittable transfer node transmits (retransmits) the sensor data on behalf of the accommodation designation transfer node when the sensor data transmitted from the sensor node 4 and transferred by the accommodation designation transfer node does not reach the collection server 1. This is information of the forwarding node 3 that can be used. The identifier of the forwarding node 3 that operates as a retransmittable forwarding node is registered in the identifier. In the reception level, the level of a signal received by the transfer node 3 registered as a retransmittable transfer node from the sensor node 4 that is the transmission source of the sensor data to be retransmitted is registered. When the retransmittable transfer node receives the sensor data from the corresponding sensor node 4, the retransmittable transfer node holds the received sensor data for a certain period of time without transferring it to the GW node 2. Then, in response to a request from the GW node 2, the held sensor data is transmitted to the GW node 2. The sensor node accommodation table 25 illustrated in FIG. 3 indicates that, for example, the sensor node 4b is accommodated in the transfer node 3B, and the transfer node 3B transfers the sensor data transmitted by the sensor node 4b. Further, the level of the signal received by the forwarding node 3B from the sensor node 4b is 80. Further, the retransmittable transfer node corresponding to the sensor node 4b is the transfer node 3C, and the level of the signal received by the transfer node 3C from the sensor node 4b is 60. Further, the forwarding node 3B indicates that the sensor node 4a is a retransmittable forwarding node. Therefore, when receiving the sensor data from the sensor node 4b, the transfer node 3B transfers the data to the GW node 2. On the other hand, when sensor data is received from the sensor node 4a, the sensor data is held for a certain time without being transferred to the GW node 2. When the transfer node 3C receives the sensor data from the sensor node 4b, the transfer node 3C holds the sensor data for a certain time without performing the transfer toward the GW node 2.

  The sensor data reception status is information indicating whether or not the GW node 2 has received sensor data. The sensor node accommodation table 25 illustrated as an example in FIG. 3 shows a state in which the GW node 2 has not received sensor data from the sensor node 4a and has already received sensor data from the sensor nodes 4b and 4c.

  FIG. 4 is a diagram illustrating a configuration example of the forwarding node 3. The transfer node 3 includes a transmission unit 31 that transmits sensor data to the GW node 2, a reception unit 32 that receives a transmission request from the GW node 2, and a sensor data reception unit that receives sensor data transmitted from the sensor node 4. 33, a sensor node accommodation determination unit 34 for determining whether the sensor data received from the sensor node 4 is to be transmitted to the GW node 2 or retained, and information for determining the processing contents for each sensor node 4 are retained. A sensor node accommodation table 35 to be stored, and a sensor data temporary storage unit 36 to store sensor data.

  FIG. 5 is a diagram illustrating a configuration example of the sensor node accommodation table 35 held by the forwarding node 3. As illustrated, in the sensor node accommodation table 35, a sensor node identifier, a sensor node accommodation state, and temporary storage of sensor data are registered. In other words, the sensor node identifier and the sensor data temporary storage are registered in association with the sensor node identifier.

  In the sensor node identifier, identifiers of all sensor nodes 4 forming the sensor network are registered.

  The sensor node accommodation state is information indicating a relationship with the associated sensor node 4. This information indicates whether or not the sensor node 4 indicated by the sensor node identifier is accommodated in itself (self-transfer node), and whether or not the sensor node 4 is a transfer node that transfers sensor data. And whether or not it is responsible for retransmission of the sensor data of the sensor node 4 indicated by the sensor node identifier (whether or not it corresponds to the retransmittable transfer node shown in FIG. 3). When the sensor node accommodation state is “own node: temporary storage”, when the corresponding sensor node 4 (sensor node 4 indicated by the sensor node identifier) is accommodated in itself and sensor data transmitted from the sensor node 4 is received. Indicates that it is necessary to transfer the sensor data and hold it for a certain period of time, that is, it corresponds to the accommodation designated transfer node. When the sensor node accommodation state is “other node: temporary storage”, when the corresponding sensor node 4 is accommodated in another transfer node and sensor data transmitted from the sensor node 4 is received, it is necessary to hold for a certain period of time. It indicates that it corresponds to a retransmittable forwarding node. When the sensor node accommodation state is “other node: storage unnecessary”, the corresponding sensor node 4 is accommodated in another node, and it is not necessary to hold the sensor data transmitted from the sensor node 4 for a certain period of time. This indicates that the node itself does not correspond to either the accommodation designation transfer node or the retransmittable transfer node. When the sensor node accommodation state is “undecided”, it indicates that the transfer node (accommodation designated transfer node) accommodating the corresponding sensor node 4 has not been determined. When receiving the sensor data from the sensor node 4a, the transfer node 3 holding the sensor node accommodation table 35 shown in FIG. 5 transfers the data to the GW node 2 and holds the sensor data for a certain period of time. When sensor data is received from the sensor node 4b, the sensor data is held for a certain period of time without being transferred to the GW node 2 (when the request is received from the GW node 2, the held sensor data is transmitted). ). When sensor data is received from the sensor node 4c, the sensor data is discarded without being transferred to the GW node 2. Even when sensor data is received from the sensor node 4d, the sensor data is discarded without being transferred to the GW node 2.

  The sensor data temporary storage is information indicating whether or not it is necessary to temporarily store the sensor data when the sensor data is received from the associated sensor node 4 (sensor node 4 indicated by the sensor node identifier). For example, when there are three or more transfer nodes 3 that can receive sensor data from a certain sensor node 4, some transfer nodes 3 are set to devices that do not transfer or temporarily hold the received sensor data. It can be done. This information may be included in the sensor node accommodation state. That is, the sensor node accommodation state is any of the accommodation designation transfer node, retransmittable transfer node, and other nodes (nodes that do not correspond to either the accommodation designation transfer node or the retransmittable transfer node) for each sensor node 4 May be omitted if it clearly indicates whether or not

  FIG. 6 is a diagram illustrating a configuration example of the sensor node 4. The sensor node 4 transfers sensor data, a sensor unit 41 that obtains information such as the temperature of the measurement target, a sensor data generation unit 42 that edits information obtained from the sensor unit 41 as sensor data (generates sensor data), and the like. A sensor data wireless transmission unit 43 that transmits data to the node 3 and a control unit 44 that manages the operation of the sensor node 4 such as intermittently starting itself (the sensor node 4) according to a predetermined schedule.

(Basic operation of sensor network system)
Next, the basic operation of the sensor network system according to this embodiment will be described. FIG. 7 is a diagram showing a basic operation of each device in the sensor network system having the configuration shown in FIG. In the example shown in FIG. 7, the transfer node 3A accommodates the sensor node 4a and operates as an accommodation designation transfer node of the sensor node 4a. The transfer node 3B accommodates the sensor node 4b and operates as an accommodation designation transfer node of the sensor node 4b, and the transfer node 3C accommodates the sensor node 4c and operates as an accommodation designation transfer node of the sensor node 4c. .

  The sensor node 4 generates and transmits sensor data at a predetermined timing, and the collection server 1 collects the sensor data. More specifically, the sensor node 4 manages sensor data collection and data transmission operations in the control unit 44 (see FIG. 6), and the sensor data generation unit 42 uses the data detected by the sensor unit 41 as a predetermined sensor. The data is generated and passed to the sensor data wireless transmission unit 43. The sensor data wireless transmission unit 43 transmits the sensor data received from the sensor data generation unit 42 by broadcast without specifying a destination. The broadcast sensor data is received by one or more transfer nodes 3.

  For example, in the operation example shown in FIG. 7, sensor data a (denoted as “data a” in FIG. 7) transmitted from the sensor node 4a is received by the transfer node 3A and the transfer node 3B, and from the sensor node 4b. The transmitted sensor data b is received by the transfer node 3B and the transfer node 3C. Note that collection and transmission of sensor data are periodically performed according to a schedule determined in advance by the sensor node 4. In addition, during the time when sensor data is not collected and transmitted, functions other than the functions necessary for starting the periodic processing of the control unit 44, for example, the functions of the sensor unit 41, the sensor data generation unit 42, and the sensor data wireless transmission unit 43 Assume that low power consumption is realized by putting the system in a hibernation state.

  In the transfer node 3 that has received the sensor data from the sensor node 4, the sensor data received by the sensor data receiving unit 33 (see FIG. 4) and its reception level are passed to the sensor node accommodation determining unit 34. The sensor node accommodation determination unit 34 temporarily stores the received sensor data in the sensor data temporary storage unit 36. Further, the sensor node accommodation determination unit 34 refers to the sensor node accommodation table 35 (see FIG. 5) and transfers the sensor data to the transmission unit 31 when determining that the sensor data is received from the sensor node 4 accommodated by itself. The transmission unit 31 transmits the sensor data and the reception level when the sensor data is received from the sensor node 4 to the GW node 2.

  In the operation example shown in FIG. 7, when the transfer node 3A that accommodates the sensor node 4a receives the sensor data a, the transfer node 3A transfers it to the GW node 2, and the transfer node 3B that accommodates the sensor node 4b receives the data b. Then, the data is transferred to the GW node 2. When receiving the data c, the transfer node 3C that accommodates the sensor node 4c transfers the data to the GW node 2. Further, since the transfer node 3B does not accommodate the sensor node 4a, when the sensor data a is received, it is temporarily stored without being transferred. Since the transfer node 3C does not accommodate the sensor node 4b, when the sensor data b is received, it is temporarily stored without being transferred.

  The sensor data temporary storage unit 36 of the transfer node 3 can hold a finite number of sensor data received from each sensor node 4, and the sensor data is stored when a predetermined time has elapsed after storing the sensor data to be held for a certain period of time. Discard the data. Alternatively, instead of discarding when the predetermined time has elapsed, new sensor data to be retained is received from the sensor node 4 and when the storage area of the sensor data is insufficient, the sensor data is received from the sensor node 4 The oldest sensor data held is discarded and new sensor data is stored.

  The GW node 2 receives the sensor data transmitted from the transfer node 3 by the sensor data receiving unit 22 (see FIG. 2). The sensor node accommodation management unit 24 updates the sensor node accommodation table 25 (see FIG. 3) based on the information of the sensor node 4 that is the transmission source of the received sensor data. That is, one or more of the information of the accommodation designation transfer node, the retransmittable transfer node, and the sensor data reception status is updated. The sensor node accommodation management unit 24 also passes the received sensor data to the server interface unit 21 and transmits it to the collection server 1.

(Operation of sensor network system when unregistered sensor node exists)
Next, an operation when there is an unregistered sensor node 4 in which the transfer node 3 as the accommodation destination has not been determined will be described. As an example, the operation when the sensor node 4 is newly installed will be described. FIG. 8 is a sequence diagram showing an example of operation when the sensor node 4 is newly installed. FIG. 8 shows an operation sequence of the transfer node 3 and the GW node 2 when the sensor node 4a first transmits the sensor data a after the sensor node 4a is newly installed in the system having the configuration shown in FIG. ing.

  First, when the newly installed sensor node 4a transmits the sensor data (sensor data a) (step S11), the transfer nodes 3A and 3B existing in the signal reachable range 5a of the sensor node 4a become the sensor data a. Is received (steps S12A, 12B). In the transfer nodes 3A and 3B that have received the sensor data a, the sensor node accommodation determination unit 34 refers to the sensor node accommodation table 35 (FIG. 5), and as a result, the identifier of the sensor node 4a is registered in the sensor node identifier. Figure out what is not. At this time, since the transfer node 3 that accommodates the sensor node 4a has not been determined, the identifier of the sensor node 4a is registered in the sensor node identifier, and “undecided” is registered in the sensor node accommodation state (step S13A, 13B). At this time, since the transfer node 3 (= accommodation designated transfer node) in charge of data transfer of the sensor node 4a is not determined, both the transfer nodes 3A and 3B that have received the sensor data a are connected to the sensor data a and the sensor data. The reception level of data a is transmitted to GW node 2 (steps S14A and 14B). At this time, information (identifier) of the sensor node 4a that is the transmission source of the sensor data a is also transmitted together. The reception level of the sensor data “a” is information used in the process in which the GW node 2 determines the accommodation destination of the sensor node 4a. Steps S14A and S14B are not executed when the accommodation destination of the sensor node 4a is determined. When the accommodation destination of the sensor node 4a is determined, the transfer node 3 of the accommodation destination transfers the sensor data a (the reception level of the sensor data a is not transmitted).

  When the GW node 2 receives the sensor data for a certain period and receives the sensor data a and the reception level information from the transfer nodes 3A and 3B, the GW node 2 converts the reception level information and the information of the transmission source sensor node of the sensor data a. Based on this, the sensor node accommodation table 25 (FIG. 3) is updated (step S15). Specifically, the sensor node accommodation management unit 24 first registers the identifier of the sensor node 4a that is the transmission source of the sensor data a in the sensor node identifier. Next, an accommodation designation transfer node and a retransmittable transfer node are determined. For example, the transfer node 3 having the higher reception level of the sensor data a is determined as the accommodation designated transfer node, and the remaining transfer nodes 3 are determined as the retransmittable transfer nodes. When sensor data a is received from only one transfer node 3, the transfer node 3 is determined as an accommodation designation transfer node. When sensor data a is received from three or more transfer nodes 3, the transfer node 3 having the highest reception level of sensor data a is determined as the accommodation designated transfer node, and the transfer node 3 having the second highest transfer node 3 is reconnected. What is necessary is just to determine to the transmission possible transmission node. Alternatively, the transfer node 3 having the highest reception level of the sensor data a may be determined as an accommodation designated transfer node, and all other (remaining) transfer nodes 3 may be determined as retransmittable transfer nodes. Here, the description will be continued on the assumption that the forwarding node 3A is determined as the accommodation designated forwarding node and the forwarding node 3B is determined as the retransmittable forwarding node.

  When the sensor node accommodation management unit 24 of the GW node 2 determines the accommodation designated transfer node and the retransmittable transfer node, the sensor node accommodation table 25 is updated according to the determination result (the determined accommodation designated transfer node and the retransmittable transfer node determined). Is registered in the sensor node accommodation table 25). When the update of the sensor node accommodation table 25 is completed, the update result, that is, the accommodation designation transfer node and the retransmittable transfer node of the sensor node 4a are notified to the transfer nodes 3A and 3B (step S16). Further, the sensor data reception status of the sensor node accommodation table 25 is updated ("Reception" is registered in the sensor data reception status), and the sensor data a is stored in a transmission buffer (not shown) in the server interface unit 21 ( Steps S17 and S18).

  When the forwarding nodes 3A and 3B receive the notification in step S16, the forwarding nodes 3A and 3B update the sensor node accommodation table 35 (FIG. 5) (steps S19A and S19B). Here, since the transfer node 3A is an accommodation designation transfer node and the transfer node 3B is a retransmittable transfer node, the sensor node accommodation determination unit 34 of the transfer node 3A has a sensor node 4a of the sensor node accommodation table 35 held therein. "Self-node: Temporary storage" indicating that it is an accommodation-designated transfer node is registered for the sensor node accommodation state corresponding to. On the other hand, the sensor node accommodation determination unit 34 of the forwarding node 3B indicates that it is a retransmittable forwarding node with respect to the sensor node accommodation state corresponding to the sensor node 4a of the sensor node accommodation table 35 held therein. “Other node: Temporary storage” is registered.

  In this way, the transfer node 3 that is the accommodation destination of the newly installed sensor node 4a and the transfer node 3 that can handle the retransmission of the sensor data are determined. In addition, the sensor node accommodation table 35 managed by the transfer nodes 3A and 3B capable of direct communication with the sensor node 4a is updated, and the sensor node accommodation table 25 managed by the GW node 2 is updated. The

  Although the operation example when the sensor node 4 is newly installed has been described, the transfer node 3 receives sensor data from the sensor node 4 that is not registered in the held sensor node accommodation table 35. If it is, the received level is transferred to the GW node 2 together with the received sensor data, and the GW node 2 transfers the sensor node 4 that is the transmission source of the received sensor data (= accommodation designated transfer node). Then, the forwarding node 3 (= retransmissible forwarding node) responsible for data retransmission is determined.

  As described above, in the sensor network system according to the present embodiment, when the sensor data is transmitted from the sensor node 4 for the first time after the sensor node 4 is newly installed, the transfer node 3 includes the sensor node accommodation table 35. When sensor data is received from a sensor node 4 that is not registered, the information of the sensor node 4 is newly added to the sensor node accommodation table 35, and the received sensor data and reception level are transmitted to the GW node 2. When the GW node 2 receives one or more sensor data transmitted from the sensor node 4 (hereinafter, unregistered sensor node) not registered in the sensor node accommodation table 25 via one or more transfer nodes 3, From the reception level information transmitted from the transfer node 3 together with the sensor data, the transfer node 3 responsible for transferring the sensor data transmitted by the unregistered sensor node to the GW node 2 is determined. Further, the transfer node 3 that can transfer the sensor data from the unregistered sensor node is determined. Then, the sensor node accommodation table 25 is updated according to the determination result, and the determination result is notified to each transfer node 3. The determination result to be notified includes the transfer node 3 that transfers when sensor data from an unregistered sensor node is received, the transfer node 3 that holds the received sensor data for a certain period, and the need to hold the received sensor data This is information indicating that there is no forwarding node 3. The transfer node 3 that has received the notification of the determination result updates the sensor node accommodation table 35.

(Sensor data transmission operation in the sensor network system)
Next, an operation when the sensor node 4 (registered sensor node) whose accommodation destination has been determined transmits sensor data will be described. FIG. 9 is a sequence diagram illustrating an example of an operation in which the registered sensor node 4 transmits sensor data. FIG. 9 shows an operation sequence of the transfer node 3 and the GW node 2 when the registered sensor node 4a transmits the sensor data a in the system having the configuration shown in FIG. The accommodation designated transfer node of the sensor node 4a is referred to as a transfer node 3A, and the retransmittable transfer node is referred to as a transfer node 3B. The same steps as those already described in FIG. 8 are given the same step numbers.

  The sensor node 4a transmits the sensor data a at a predetermined timing (step S11), and the sensor data a reaches the transfer nodes 3A and 3B.

  When the transfer node 3A receives the sensor data a (step S12A), the transfer node 3A refers to the sensor node accommodation table 35 and confirms that it has been received from the sensor node 4a contained therein (step S21A). Data a is transmitted to the GW node 2 (step S22A). At this time, the reception level when the sensor data a is received is also transmitted. On the other hand, when the transfer node 3B receives the sensor data a (step S12B), the transfer node 3B refers to the sensor node accommodation table 35 and receives it from the sensor node 4a accommodated in the transfer node 3A, but holds it for a certain period. It is confirmed that it is necessary (step S21B). And the sensor data a are stored in the sensor data temporary storage part 36 (step S22B). In step S22A, the forwarding node 3A transmits the sensor data a and the reception level, but transmission of the reception level may be omitted.

  When receiving the sensor data a, the GW node 2 updates the sensor data reception status of the sensor node accommodation table 25 (step S17). That is, “reception” is registered in the sensor data reception status. Further, the sensor data a is stored in a transmission buffer (not shown) in the server interface unit 21 (step S18).

(Retransmission operation of sensor data in sensor network system)
Next, the operation of retransmitting sensor data, specifically, the operation when the GW node 2 detects a sensor data reception error and requests the transfer node 3 to retransmit the data will be described.

  FIG. 10 is a diagram showing an outline of an operation for retransmitting sensor data in the sensor network system having the configuration shown in FIG. 1, and as an example, an example of an operation for retransmitting sensor data a transmitted from the sensor node 4a. Is shown. FIG. 11 is a sequence diagram corresponding to the operation shown in FIG. The accommodation designated transfer node of the sensor node 4a is referred to as a transfer node 3A, and the retransmittable transfer node is referred to as a transfer node 3B. In FIG. 11, the same step numbers are assigned to the same processes as those already described in FIGS. 8 and 9.

  As described with reference to FIG. 9, the sensor data a transmitted from the sensor node 4a is received by the transfer nodes 3A and 3B, and the transfer node 3A that is the accommodation designation transfer node of the sensor node 4a The reception level is transmitted to the GW node 2 (steps S12A, S21A, S22A). On the other hand, the transfer node 3B, which is a retransmittable transfer node of the sensor node 4a, holds the sensor data a (steps S12B, S21B, S22B).

  The sensor node accommodation management unit 24 of the GW node 2 receives the sensor data transmitted from a certain sensor node 4 periodically or in order, and observes the reception cycle, the sequence number of the received sensor data, and the like. By doing so, it is possible to detect non-reception of sensor data. When the sensor data accommodation management unit 24 detects that the sensor data has not been received, the sensor data accommodation management unit 24 refers to the sensor node accommodation table 25 and transmits the sensor data to the retransmittable transfer node holding the unreceived sensor data. Request. That is, when the non-reception of the sensor data a transmitted from the sensor node 4a is detected, the transmission of the sensor data a is requested to the transfer node 3B set as the retransmittable transfer node of the sensor node 4a. (Step S31). When requesting transmission, by notifying the sensor data transmission source (sensor node) information, sensor data collection time (time when the sensor data was transmitted from the sensor node), sensor data sequence number, etc. Specify the sensor data to request transmission.

  When the transfer node 3B receives a transmission request for the sensor data a from the GW node 2, the transfer node 3B searches the sensor data held in the sensor data temporary storage unit 36 by the sensor node accommodation determination unit 34, and transmits the sensor data to be transmitted. If a is held, it is transmitted to the GW node 2 (step S32). If the sensor data a that is the transmission request target is not held, it is transmitted to the GW node 2 as no sensor data. In this case, the GW node 2 may request the accommodation designation transfer node to transmit sensor data.

  As shown in FIG. 10, when the sensor data a transmitted from the sensor node 4a cannot be received by the GW node 2 via the transfer node 3A, the sensor data a is received and temporarily stored in the transfer node 3B. It requests the transmission of sensor data a to obtain sensor data a. Note that the sensor data a transmitted from the transfer node 3B at this time may be received by the transfer node 3A, but the sensor data a is already transmitted to the GW node 2 at the transfer node 3A. Even if it is received, it is discarded without being transferred or stored elsewhere.

  As described above, in the sensor network system of the present embodiment, the GW node 2 includes the transfer node 3 (= accommodation designated transfer node) responsible for transferring the sensor data transmitted from each sensor node 4 in the system, When the sensor data transmitted from the sensor node 4 is received, the transfer node 3 (= retransmittable transfer node) that retains the sensor data without performing the transfer is determined and executed for each transfer node 3 Specify the action. When the transfer node 3 receives the sensor data, the transfer node 3 refers to the sensor node accommodation table 35, and the transfer node 3 itself receives the accommodation designation transfer node, the retransmittable transfer node, and other transfer nodes (does not transfer or hold the received sensor data). The transfer process is executed after confirming which of the transfer nodes is applicable. When the GW node 2 detects that no sensor data has been received, the GW node 2 requests the transfer node 3 that is a retransmittable transfer node corresponding to the sensor data to transmit the sensor data, and receives the request. The forwarding node 3 transmits the requested sensor data if it is held. As a result, if there is a failure due to interference or the like in the wireless transmission path between the accommodation designated transfer node and the GW node 2 and the transmission of the sensor data is not successful, the path where the failure has occurred is avoided and the sensor data Can be collected. Therefore, the success rate of retransmission can be increased, and a highly reliable sensor network system can be realized.

Embodiment 2. FIG.
Next, the sensor network system according to the second embodiment will be described. The system configuration is the same as that of the first embodiment (see FIG. 1). The internal configuration of each device (GW node, forwarding node, sensor node) is the same as that in the first embodiment (see FIGS. 2 to 6).

  The sensor node accommodation management unit 24 of the GW node 2 receives the sensor data transmitted from a certain sensor node 4 periodically or in order, and observes the reception cycle, the sequence number of the received sensor data, and the like. By doing so, it is possible to detect the continuous deterioration of the communication state with the sensor node 4 due to frequent reception of sensor data from the transfer node 3 (= accommodation designated transfer node) instructing the accommodation of the sensor node 4. .

  Therefore, in the present embodiment, when the GW node 2 detects a continuous deterioration in the communication state between a certain sensor node 4 and the transfer node 3 that accommodates the sensor node 4, the GW node 2 applies to each transfer node 3 in the system. And instructing the accommodation of the target sensor node 4 (the sensor node 4 that has detected the deterioration of the communication state) to the unaccommodated state. Then, by collecting the sensor data and the reception level information from each transfer node 3 again by the procedure shown in FIG. 8, the transfer node 3 suitable for accommodating the sensor node 4 is determined again (sensor node 4 Accommodation change process).

  In addition, the sensor node accommodation management unit 24 of the GW node 2 may inhibit the transmission of sensor data from the sensor node 4 by instructing all the transfer nodes 3 to accommodate other nodes with respect to a certain sensor node 4. Is possible.

  As described above, according to the present embodiment, when the communication environment changes, the accommodation destination of the sensor node 4 is changed to the optimum transfer node 3, so that high reliability can be maintained.

  In the present embodiment, the GW node 2 changes the accommodation destination of the sensor node 4 of the sensor data transmission source when the sensor data is not received frequently. The necessity determination may be performed based on the reception level.

  For example, every time the GW node 2 receives sensor data, the reception level (latest reception level) transmitted together with the sensor data and the reception level registered in the sensor node accommodation table 25 (for example, accommodation designation) Compare the reception level of the forwarding node). When the state where the latest reception level is significantly lower than the registered reception level continues for a certain period of time, it is determined that the accommodation destination change of the corresponding sensor node 4 is necessary. Alternatively, the latest reception level is compared with the reception level of the retransmittable transfer node (reception level registered in the sensor node accommodation table 25), and the reception level of the retransmittable transfer node is higher than the latest reception level. Is determined for a certain period of time, it is determined that the accommodation destination of the corresponding sensor node 4 needs to be changed.

Embodiment 3 FIG.
Next, the sensor network system according to the third embodiment will be described. The system configuration is the same as that of the first embodiment (see FIG. 1). The internal configuration of each device (GW node, forwarding node, sensor node) is the same as that in the first embodiment (see FIGS. 2 to 6).

  12 and 13 are diagrams illustrating the operation of each device in the sensor network system according to the third embodiment. Note that the accommodation designation transfer node of the sensor node 4a is the transfer node 3A, the accommodation designation transfer node of the sensor node 4b is the transfer node 3B, and the accommodation designation transfer node of the sensor node 4c is the transfer node 3C.

  In the sensor network system according to the first and second embodiments, the retransmittable transfer node holds the sensor data directly received from the sensor node 4 and transmits the sensor data in response to a request from the GW node 2. On the other hand, in the sensor network system according to the present embodiment, each transfer node 3 receives and holds sensor data transmitted from the other transfer nodes 3 to the GW node 2 (FIG. 12). reference). As shown in FIG. 12, for example, sensor data a transferred by the transfer node 3A and sensor data c transferred by the transfer node 3C arrive at the transfer node 3B. Therefore, the sensor data a and c are held. Keep it.

  For example, when the sensor data a cannot be received from the transfer node 3A due to a communication failure, the GW node 2 requests the transfer node 3B to transmit the sensor data a. Upon receiving this request, the transfer node 3B transmits the held sensor data a to the GW node 2. At this time, the sensor data a transmitted from the transfer node 3B may be received by the transfer node 3A. However, since the transfer node 3A is already transmitted to the GW node 2, the sensor data a Even if it is received, it is discarded without being transferred or stored elsewhere (see FIG. 13).

  As described above, in the sensor network system according to the present embodiment, when the forwarding node 3 receives the sensor data transmitted from the other forwarding node 3 to the GW node 2, the forwarding node 3 holds the sensor data. If the sensor data specified by the transmission request received from is held, it is transmitted. As a result, similar to the first embodiment, it is possible to retransmit the sensor data while avoiding the path where the communication failure has occurred.

  As described above, the node device according to the present invention is useful as a node device that forms a sensor network system.

  DESCRIPTION OF SYMBOLS 1 Collection server, 2 Gateway (GW) node, 3A, 3B, 3C Forwarding node, 4a, 4b, 4c Sensor node, 5a, 5b, 5c Signal reachable range, 21 Server interface part, 22, 33 Sensor data receiving part, 23 , 31 Transmission unit, 24 Sensor node accommodation management unit, 25, 35 Sensor node accommodation table, 32 Reception unit, 34 Sensor node accommodation determination unit, 36 Sensor data temporary storage unit, 41 Sensor unit, 42 Sensor data generation unit, 43 Sensor Data wireless transmission unit, 44 control unit.

Claims (9)

A sensor node; a collection server for collecting sensor data from the sensor node; a transfer node for transferring the sensor data toward the collection server; and a sensor network together with the sensor node and the transfer node; And a gateway node that connects the sensor network, a node device that operates as the forwarding node in a sensor network system comprising:
A data transfer means for transferring the received sensor data when receiving the sensor data instructed in advance from the gateway node so as to be responsible for the transfer process;
Holding means for holding the received sensor data when receiving sensor data in advance instructed by the gateway node so that a node device other than itself is in charge of transfer processing;
A data transmission unit for transmitting to the gateway node if the holding unit holds the requested sensor data when receiving a transmission request for the sensor data from the gateway node;
A node device comprising: The data transfer means includes
When sensor data for which a node device in charge of transfer processing has not been determined has been received, the received sensor data and information on the reception level thereof are transferred to the gateway node, and the node device in charge of the transfer processing of the sensor data is Make a decision based on the reception level information,
The node device according to claim 1, wherein:   The holding means holds the received sensor data when receiving sensor data transmitted from the sensor node and instructed in advance by the gateway node so that a node device other than itself is in charge of transfer processing. The node device according to claim 1, wherein:   The holding means holds the received sensor data when receiving the sensor data transferred by another node device and instructed in advance by the gateway node so that a node device other than itself is in charge of the transfer process. The node device according to claim 1, wherein the node device is stored in advance. A sensor node; a collection server for collecting sensor data from the sensor node; a transfer node for transferring the sensor data toward the collection server; and a sensor network together with the sensor node and the transfer node; And a gateway node that connects the sensor network, and a gateway device that operates as the gateway node in a sensor network system comprising:
When sensor data transmitted from the same sensor node is received via different transfer nodes, the sensor node receives the received sensor data based on a reception level when each transfer node of the transfer source receives the sensor data from the sensor node. A transfer node determining means for determining a transfer node for transferring sensor data to be transmitted after the next time, and for determining a transfer node for holding the sensor data to be transmitted by the sensor node for the next time; and
A transmission request means for detecting a sensor data reception failure and requesting transmission of the sensor data to a transfer node different from the transfer node responsible for transferring the sensor data that could not be received;
A gateway device comprising: State monitoring means for monitoring the communication state with the forwarding node determined by the forwarding node determining means;
Further comprising
When the state monitoring means detects the deterioration of the communication state,
6. The gateway according to claim 5, wherein the transfer node determination unit changes the transfer of sensor data handled by a transfer node whose communication state is deteriorated so that another transfer node is responsible for the transfer. apparatus.   The state monitoring means determines that the communication state with the transfer node in charge of transfer of the sensor data has deteriorated when reception of sensor data transmitted from a specific sensor node cannot be received for a certain period of time. The gateway device according to claim 6, wherein: A sensor node; a collection server for collecting sensor data from the sensor node; a transfer node for transferring the sensor data toward the collection server; and a sensor network together with the sensor node and the transfer node; And a gateway node connecting the sensor network, a sensor network system comprising:
The gateway node is
When sensor data transmitted from the same sensor node is received via different transfer nodes, the sensor node receives the received sensor data based on a reception level when each transfer node of the transfer source receives the sensor data from the sensor node. A transfer node determining means for determining a transfer node for transferring sensor data to be transmitted after the next time, and for determining a transfer node for holding the sensor data to be transmitted by the sensor node for the next time; and
A transmission request means for detecting a sensor data reception failure and requesting transmission of the sensor data to a transfer node different from the transfer node responsible for transferring the sensor data that could not be received;
With
The forwarding node is
When the sensor data instructed in advance by the gateway node to receive the transfer process is received, the received sensor data is transferred, and the sensor data for which the transfer node in charge of the transfer process is not determined is received. Is a data transfer means for transferring the received sensor data and the information of the reception level;
A holding means for holding the received sensor data when receiving the sensor data instructed in advance from the gateway node so that a transfer node other than itself is in charge of the transfer process;
A data transmission unit for transmitting to the gateway node if the holding unit holds the requested sensor data when receiving a transmission request for the sensor data from the gateway node;
A sensor network system comprising: A sensor node; a collection server for collecting sensor data from the sensor node; a transfer node for transferring the sensor data toward the collection server; and a sensor network together with the sensor node and the transfer node; And a gateway node for connecting the sensor network, a data transfer method executed by the transfer node in a sensor network system comprising:
A data transfer step of transferring the received sensor data when receiving the sensor data instructed in advance from the gateway node so as to be responsible for the transfer process;
A data holding step for holding the received sensor data without transferring when receiving sensor data instructed in advance from the gateway node so that a transfer node other than itself is in charge of the transfer process;
When a sensor data transmission request is received from the gateway node, a data transmission step for transmitting to the gateway node if the requested sensor data is held;
A data transfer method comprising:

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