JP2007004390A - Sensor network system, cluster formation method, and sensor node - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve processing efficiency in summarization of sensor data and to reduce traffic quantity and power consumption in a sensor network. <P>SOLUTION: A sensor node 10a with the highest residual capacity of a power source in sensing an event is used as a cluster head. Other sensor nodes 10b-10f transmit participation messages to a temporary cluster T to the cluster head 10 when it is determined that the type and detection time of the event in the cluster head are similar to those in their own nodes. In this way, the temporary cluster T is formed. A member of the temporary cluster T transmits the participation message to an eternal cluster E to the cluster head 10a when it is determined that an analysis result of the event in the cluster head is similar to that of its own node. In this way, the eternal cluster E is formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sensor network system, a cluster formation method, and a sensor node.

In recent years, management of various facilities, observation of environments, and the like have been performed using a sensor network formed by a large number of sensor nodes with built-in batteries. Non-Patent Document 1 below discloses a sensor network technology in which a cluster is formed by sensor nodes adjacent to an event to be sensed and an event is sensed in cooperation within the cluster.
Independent data aggregation mechanism in sensor networks (http://www.ubi.cs.ritsumei.ac.jp/~shuma/paper/2004_spa-summer_shuma.ppt)

  By the way, in the above-described sensor network technology, a cluster is formed without considering sensor data of a sensed event at all. Therefore, a cluster may be formed between sensor nodes having a low correlation. In such a case, the processing efficiency when collecting the sensor data is reduced, and the traffic amount and power consumption in the sensor network are increased.

  Therefore, in order to solve the above-described problem, the present invention improves the processing efficiency when aggregating sensor data, and can reduce the traffic volume and power consumption in the sensor network, and cluster formation It is an object to provide a method and a sensor node.

  The sensor network system of the present invention is a sensor network system having a cluster formed by one sensor node serving as a cluster head and another sensor node serving as a member. A first determination means for determining whether or not the two events are in a similar relationship based on a type of the event sensed in the node and the one sensor node and a detection time; the other sensor node and the one sensor node; Second determination means for determining whether or not both events are in a similar relationship based on the analysis result of the sensed event, wherein the one sensor node detects that both events are detected by the first determination means. Temporary member registration means for registering other sensor nodes determined to be in a similar relationship as members of a temporary cluster, and a temporary class Member registration means for registering other sensor nodes that are registered in the cluster and other sensor nodes determined by the second determination means as having a similar relationship with each other, as members of the cluster. It is characterized by providing.

  The cluster forming method of the present invention is a method of forming a cluster having one sensor node as a cluster head and another sensor node as a member, wherein the other sensor node is the other sensor node. A first determination step for determining whether or not the two events are in a similar relationship based on a type of the event sensed in the node and the one sensor node and a detection time; and the one sensor node includes: The temporary sensor registration step of registering other sensor nodes determined to have similar relationships in the determination step as members of the temporary cluster, and the other sensor nodes registered as members of the temporary cluster include the other sensor nodes. Based on the analysis result of the event detected at one sensor node and one sensor node, whether or not both events are in a similar relationship A second determination step for determining whether the first sensor node is a member of this cluster, and the other sensor node for which both events are determined to be in a similar relationship in the second determination step. And a step.

  According to these inventions, it is possible to determine whether or not both events are in a similar relationship based on the type and detection time of the event sensed in another sensor node and one sensor node. When it is determined that both events are in a similar relationship, another sensor node can be registered as a member in a temporary cluster in which one sensor node is a cluster head. Thereby, a temporary cluster can be formed with a group of sensor nodes having a similar relationship between the event type and the detection time. In addition, according to these inventions, it is possible to determine whether or not both events are in a similar relationship based on the analysis result of the event sensed in another sensor node and one sensor node forming the temporary cluster. If it is determined in this determination that the two events are in a similar relationship, another sensor node can be registered as a member in the cluster where one sensor node is the cluster head. Thereby, this cluster can be formed in the sensor node group in which the analysis result of an event has a similar relationship among the sensor node groups which form a temporary cluster. Therefore, according to these inventions, it is possible to improve the processing efficiency when collecting sensor data, and to reduce the traffic volume and power consumption in the sensor network.

  In the sensor network system of the present invention, after the waiting time set for the one sensor node to become shorter as the remaining capacity of the power supply when an event is sensed increases, the type and detection time of the sensed event It is preferable to further comprise cluster head declaration distribution means for distributing a cluster head declaration including

  As a result, the one sensor node that has delivered the cluster head declaration first can be the cluster head of the temporary cluster and the main cluster. In other words, the one sensor node with the largest remaining capacity of the power supply when an event is sensed can be the cluster head.

  In the sensor network system of the present invention, when the other sensor node determines that the two events are in a similar relationship by the cluster head receiving unit that receives the cluster head declaration and the first determining unit, the cluster head declaration Provisional cluster participation message transmitting means for transmitting to the one sensor node a temporary cluster participation message indicating participation in the temporary cluster having the one sensor node that has delivered the cluster as a cluster head, the first determination The means compares the event type and the detection time sensed in the other sensor node with the event type and the detection time included in the received cluster head declaration to determine whether the two events are in a similar relationship. The temporary member registration means responds to the temporary cluster participation message. Other sensor nodes, it is preferable to register a member of temporary cluster.

  In this way, the temporary cluster participation message can be transmitted from the sensor node that sensed the event having a similar relationship with the type and detection time of the event included in the cluster head declaration, and the sensor that transmitted the temporary cluster participation message. A node can be registered as a member of a temporary cluster.

  In the sensor network system of the present invention, the one sensor node transmits an event message including an analysis result of an event detected by the one sensor node to another sensor node registered as a member of the temporary cluster. A transmission means, wherein the other sensor node transmits the event message when the event message reception means for receiving the event message and the second determination means determine that both events are in a similar relationship. A cluster participation message transmitting means for transmitting to the one sensor node a cluster participation message indicating participation in the cluster with the sensor node as a cluster head. The second determination means includes: Analysis of events detected at sensor nodes And the analysis result of the event included in the received event message, it is determined whether or not the two events are in a similar relationship. Are preferably registered as members of this cluster.

  In this way, this cluster participation message can be transmitted from the sensor node that has detected an event having a similar relationship with the analysis result of the event included in the event message transmitted to the member of the temporary cluster. The sensor node that has transmitted the participation message can be added to the members of this cluster.

  In the sensor network system of the present invention, when the other sensor node determines that the two events are in a dissimilar relationship by the second determination means, the one sensor node that transmitted the event message is used as the cluster head. This cluster withdrawal message transmission means for sending a cluster withdrawal message indicating withdrawal from the cluster to one sensor node is further provided, and the member registration means is configured to send another sensor node corresponding to the cluster withdrawal message. It is preferable to delete it from the members of this cluster.

  In this way, the cluster leave message can be transmitted from a sensor node that has detected an event that is dissimilar to the analysis result of the event included in the event message transmitted to the member of the temporary cluster. The sensor node that transmitted the cluster withdrawal message can be excluded from the members of this cluster.

  The sensor node of the present invention includes a sensor means for sensing an event, a remaining capacity detecting means for detecting a remaining capacity of a power source when the event is sensed by the sensor means, and a remaining capacity detected by the remaining capacity detecting means. Depending on the capacity, the standby time setting means that sets the shorter standby time as the remaining capacity increases, and the cluster head declaration that declares that it will become the cluster head during the standby time set by the standby time setting means If not, the cluster head declaration delivery means for broadcasting the cluster head declaration including the type of event sensed by the sensor means and the detection time to other sensor nodes, and the own sensor node as the cluster head Other sensors that have received a cluster head declaration and a temporary cluster join message indicating participation in the temporary cluster A temporary member registration means for registering another sensor node corresponding to the temporary cluster participation message as a member of the temporary cluster, and an event message including an analysis result of the event detected by the sensor means, Event message transmission means for transmitting to the other sensor node corresponding to the member registered by the temporary member registration means, and this cluster participation message indicating participation in this cluster having the own sensor node as a cluster head, And a member registration means for registering another sensor node corresponding to the cluster join message as a member of the cluster when the sensor node receives it from another sensor node.

  Further, the sensor node of the present invention includes a sensor means for sensing an event, a remaining capacity detecting means for detecting a remaining capacity of a power source when the event is sensed by the sensor means, and a remaining capacity detected by the remaining capacity detecting means. Depending on the capacity, the standby time setting means that sets the shorter standby time as the remaining capacity increases, and the cluster head declaration that declares that it will become the cluster head during the standby time set by the standby time setting means In this case, the event type and detection time included in the cluster head declaration are compared with the event type and detection time sensed by the sensor means to determine whether the two events are in a similar relationship. When the first determination means and the first determination means determine that the two events are in a similar relationship, it corresponds to the cluster head declaration. Temporary cluster participation message transmitting means for transmitting a temporary cluster participation message indicating participation in a temporary cluster having another sensor node as a cluster head to the other sensor node, and analysis of an event sensed in the other sensor node An event message receiving means for receiving an event message including a result from another sensor node, an analysis result of an event included in the event message received by the event message receiving means, and an analysis result of an event detected by the sensor means In comparison, the second determination unit that determines whether or not both events are in a similar relationship and the second determination unit correspond to an event message when it is determined that the two events have a similar relationship. Participate in this cluster with other sensor nodes as cluster heads. The present cluster join message indicating, characterized in that it comprises the present cluster join message transmission means for transmitting to the other sensor node, the.

  According to the sensor network system, the cluster formation method, and the sensor node according to the present invention, it is possible to improve the processing efficiency when collecting the sensor data and reduce the traffic amount and power consumption in the sensor network.

  Hereinafter, embodiments of a sensor network system, a cluster formation method, and a sensor node according to the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted.

  FIG. 1 is a diagram for explaining the concept of a cluster formed by a plurality of sensor nodes belonging to a sensor network system. A cluster is formed by a plurality of sensor nodes 10 that sense events. The cluster includes a sensor node 10a that functions as a cluster head and sensor nodes 10b to 10f that function as members. Examples of the event include various phenomena such as a desk being struck, a person moving, and the brightness of a room changing. By forming such a cluster, it becomes possible to sense an event in cooperation with sensor nodes belonging to the same cluster, and the processing efficiency can be improved.

  As shown in FIG. 1, the cluster in this embodiment includes a temporary cluster T and a main cluster E. The temporary cluster T is a preliminary cluster formed by a group of sensor nodes expected to have a high correlation. More specifically, for example, based on the type of event sensed by a certain sensor node and the detection time of the event, it is formed by a group of sensor nodes that sense an event having a similar relationship with this event.

  This cluster E is a final cluster formed by sensor node groups that are actually determined to have a high correlation among the sensor node groups forming the temporary cluster T. More specifically, based on the result of analyzing the sensor data of the event sensed by the cluster head of the temporary cluster T, it is formed by a sensor node group that senses an event having an analysis result similar to this analysis result. The

  As described above, the present invention is characterized in that, when forming a cluster in the sensor network, the sensor nodes 10 groups that are likely to be highly correlated are clustered in stages.

  The temporary cluster T shown in FIG. 1 is formed of sensor nodes 10a that function as cluster heads and sensor nodes 10b to 10f that function as members. The cluster E is formed of sensor nodes 10a that function as cluster heads and sensor nodes 10b to 10d that function as members.

  In the present embodiment, the sensor node 10a having the largest remaining capacity of the battery (power source) is caused to function as a cluster head. Thereby, since the sensor nodes 10b to 10f having a relatively small remaining capacity can be made members of the cluster, the battery resources of the sensor nodes 10b to 10f serving as members can be saved.

  Next, a functional configuration of the sensor node 10 that forms a cluster in the sensor network will be described with reference to FIG. The sensor node 10 physically includes a CPU, a clock, a memory, a battery, a wireless interface, and a sensor, for example.

  As shown in FIG. 2, the sensor node 10 includes a sensor unit 11 (sensor unit), a remaining capacity detection unit 12 (remaining capacity detection unit), a time management unit 13 (standby time setting unit), and a module selection unit 14. The analysis result generation unit 15, the message generation unit 16, and the message transmission / reception unit 17 (cluster head declaration distribution unit, cluster head reception unit, temporary cluster participation message transmission unit, event message transmission unit, event message reception unit, this cluster A participation message transmission unit, a main cluster withdrawal message transmission unit), a determination unit 18 (first determination unit, second determination unit), and a member management unit 19 (temporary member registration unit, main member registration unit). Have. Among the functions, the member management unit 19 functions only when the sensor node 10 functions as a cluster head.

  The sensor unit 11 senses an event that has occurred around the sensor node 10. When the sensor unit 11 determines that the sensed event is an event to be sensed in the own sensor node 10, the sensor unit 11 stores sensor data related to the event in a memory. The event to be sensed can be arbitrarily set for each sensor node 10.

  The remaining capacity detection unit 12 detects the remaining capacity of the battery when an event to be sensed is detected.

  The time management unit 13 sets a standby time according to the remaining capacity detected by the remaining capacity detection unit 12. More specifically, for example, a shorter standby time is set as the remaining capacity increases. In this case, the sensor node having a smaller remaining battery capacity has a longer standby time, and the sensor node having a larger battery remaining capacity has a shorter standby time. In other words, the sensor node with the largest remaining battery capacity is set with the shortest standby time compared to other sensor nodes. In addition, the time management unit 13 performs processing related to time, for example, acquiring time when an event is detected.

  The module selection unit 14 reads sensor data stored in the memory. The module selection unit 14 selects a module registered in advance corresponding to the type of event included in the sensor data from the module group. The module selected by the module selection unit 14 is stored in advance in the memory in association with the type of event. Here, the type of event means an event including an event to be sensed and the status of the event. Specifically, for example, a desk is struck a predetermined number of times, a person has moved within a predetermined range, or the brightness of a room has changed within a predetermined illuminance range. The module corresponds to, for example, an application that performs fast Fourier transform on sensor data.

  The analysis result generation unit 15 analyzes the sensor data and generates an analysis result by executing the module selected by the module selection unit 14. As an analysis result, for example, sensor data after fast Fourier transform is applicable.

  The message generation unit 16 generates various messages exchanged with other sensor nodes. Examples of the message include a cluster head declaration, an event message, a participation message, and a withdrawal message.

  The cluster head declaration is a message for declaring becoming a cluster head. The cluster head declaration includes, for example, the identification ID of the sensor node that is the cluster head, the type of event sensed by this sensor node, and the detection time of the event.

  The event message is a message transmitted from the sensor node which is the cluster head to the sensor node registered as a member in the own cluster. The event message includes, for example, the identification ID of the sensor node that is the cluster head, the type of event detected by the sensor node that is the cluster head, and the analysis result obtained by analyzing the sensor data.

  The participation message is a message for indicating participation in the temporary cluster or the main cluster. The participation message includes, for example, an identification ID of a sensor node that is a member.

  The withdrawal message is a message for indicating withdrawal from the temporary cluster or the current cluster to which the current membership belongs. The withdrawal message includes, for example, an identification ID of a sensor node that is a member.

  The message transmission / reception unit 17 transmits or receives various messages exchanged with other sensor nodes.

  The determination unit 18 performs various determinations. Various determinations performed in the present embodiment will be exemplified below.

  The determination unit 18 compares the event type and event detection time included in the cluster head declaration with the event type and event detection time detected by the sensor unit 11, and determines whether the two events have a similar relationship. Determine whether or not. In addition, the determination unit 18 compares the analysis result of the event included in the event message received by the message transmission / reception unit 17 with the analysis result of the event generated by the analysis result generation unit 15, and the two events have a similar relationship. It is determined whether or not. Here, the criterion for determining whether or not there is a similarity relationship can be arbitrarily set on the operator side. For example, the data value of each item to be compared (for example, event type, event detection time, event analysis result) may be coded for each similar group. In this case, it is possible to determine whether or not there is a similarity relationship by comparing codes corresponding to the respective data values.

  Further, when the cluster head declaration or the event message is received, the determination unit 18 determines whether or not the sensor node that has transmitted these messages is the cluster head of the cluster to which the current sensor node belongs. To do. Depending on the result of this determination, a participation message or a withdrawal message is returned. This determination is executed only when the user already belongs to any cluster as a member, and is not executed when the user does not belong to any cluster.

  Further, the determination unit 18 has the module selected by the module selection unit 14 the same as the module at the previous event processing, and the sensor node currently registered as a member is registered as a member at the previous event processing. It is determined whether or not the sensor node is the same. Whether or not to transmit an event message is determined according to the determination result. This determination is NO when the main cluster is formed first, that is, when event processing is not yet performed in the main cluster.

  The member management unit 19 registers the sensor node that has transmitted the participation message as a temporary cluster or a member of this cluster. In addition, the member management unit 19 deletes the sensor node that has transmitted the withdrawal message from the temporary cluster or the members of this cluster.

  Next, the operation of the sensor node 10 in the present embodiment will be described with reference to FIGS. 3 and 4 are flowcharts for explaining the operation of the sensor node 10 when the temporary cluster T is formed. FIG. 3 shows the operation of the sensor node 10 when functioning as a cluster head, and FIG. 4 shows the operation of the sensor node 10 when functioning as a member. 5 and 6 are flowcharts for explaining the operation of the sensor node 10 when forming the cluster E. FIG. 5 shows the operation of the sensor node 10 when functioning as a cluster head, and FIG. 6 shows the operation of the sensor node 10 when functioning as a member.

  First, the operation of the sensor node 10 functioning as a cluster head when the temporary cluster T is formed will be described with reference to FIG. As shown in FIG. 3, the sensor unit 11 of the sensor node 10 senses an event that has occurred around the sensor node 10 (step S11). The sensor unit 11 determines whether or not the sensed event is a sensed event (step S12).

  When the sensor unit 11 determines that the sensed event is an event to be sensed (step S12; YES), the sensor unit 11 stores sensor data related to the event in a memory (step S13).

  Next, the remaining capacity detection unit 12 detects the remaining capacity of the battery (step S14).

  Next, the time management unit 13 sets a shorter standby time as the remaining capacity increases in accordance with the remaining capacity detected by the remaining capacity detection unit 12, and starts standby (step S15). If a cluster head declaration distributed by another sensor node is received during this standby (step S16; YES), the process proceeds to an operation (see FIG. 4) when functioning as a member described later (step 4). S17).

  On the other hand, when the cluster head declaration is not received during standby (step S16; NO), the message generator 16 generates a cluster head declaration with the sensor node 10 as the cluster head (step S18). The message transmitting / receiving unit 17 broadcasts the generated cluster head declaration to other sensor nodes (step S19). Then, standby for a predetermined time is started (step S20).

  During this standby, when a participation message transmitted by another sensor node is received (step S21; YES), the member management unit 19 registers the sensor node that has transmitted the participation message as a member of the temporary cluster T. (Step S22).

  Further, when the withdrawal message transmitted by another sensor node is received during the standby in step S20 (step S23; YES), the member management unit 19 designates the sensor node that has transmitted the withdrawal message in the temporary cluster T. It deletes from a member (step S24).

  Next, the operation of the sensor node 10 that functions as a member when the temporary cluster T is formed will be described with reference to FIG. As shown in FIG. 4, when the cluster head declaration is received by the message transmission / reception unit 17 of the sensor node 10 (step S31), the determination unit 18 detects the type of event included in the cluster head declaration and the detection of the event. The time is compared with the type of event sensed by the sensor unit 11 and the event detection time, and it is determined whether or not both events are in a similar relationship (step S32).

  If this determination is YES (step S32; YES), the determination unit 18 determines whether or not the sensor node that has delivered the cluster head declaration is the cluster head of the cluster to which the current sensor node 10 belongs. Determination is made (step S33). If this determination is NO (step S33; NO), the message transmitting / receiving unit 17 transmits a withdrawal message to the cluster head of the cluster to which the current sensor node 10 belongs (step S34). Next, the message transmitting / receiving unit 17 returns a participation message to the sensor node that has delivered the cluster head declaration (step S35). On the other hand, if it is determined in step S33 that the cluster head declaration is distributed from the cluster head of the cluster to which the current sensor node 10 belongs (step S33; YES), the process proceeds to step S35 described above. Transition.

  On the other hand, if it is determined in step S32 that the two events are in a dissimilar relationship (step S32; NO), the determination unit 18 determines that the sensor node to which the cluster head declaration has been distributed belongs to the current sensor node 10. It is determined whether or not it is the cluster head of the current cluster (step S36). If this determination is YES (step S36; YES), the message transmission / reception unit 17 leaves the sensor node that delivered the cluster head declaration, that is, the cluster head of the cluster to which the current sensor node 10 belongs. A message is returned (step S37).

  In this way, the sensor node with the largest remaining battery capacity is used as the cluster head, and the other sensor nodes that sense the event type and detection time that are similar to the event type and detection time sensed in this cluster head. Can be members of a temporary cluster.

  Next, the operation of the sensor node 10 that functions as a cluster head when the cluster E is formed will be described with reference to FIG. As shown in FIG. 5, the module selection unit 14 of the sensor node 10 that functions as the cluster head of the temporary cluster T reads the sensor data stored in the memory (step S41). The module selection unit 14 selects a module registered in advance corresponding to the type of event included in the sensor data from the module group (step S42).

  Next, the determination unit 18 selects the module selected by the module selection unit 14 as the module at the time of the previous event processing, and the sensor node currently registered as a member registers as a member at the time of the previous event processing. It is determined whether or not the sensor node is the same (step S43). If this determination is YES (step S43; YES), event processing is continued as it is (step S44).

  On the other hand, when the determination in step S43 is NO (step S43; NO), the analysis result generation unit 15 executes the module selected by the module selection unit 14, analyzes the sensor data, and generates an analysis result. (Step S45).

  Next, the message generator 16 generates an event message including the analysis result (step S46). The message transmitting / receiving unit 17 transmits the generated event message to the sensor node currently registered as a member (step S47). Then, standby for a predetermined time is started (step S48).

  During this standby, when a participation message transmitted by another sensor node is received (step S49; YES), the member management unit 19 registers the sensor node that has transmitted the participation message as a member of this cluster E. (Step S50).

  Further, when the withdrawal message transmitted by another sensor node is received during the standby in step S47 (step S51; YES), the member management unit 19 designates the sensor node that has transmitted the withdrawal message as the cluster E. It deletes from a member (step S52).

  Next, the operation of the sensor node 10 that functions as a member when the cluster E is formed will be described with reference to FIG. As shown in FIG. 6, when an event message is received by the message transmission / reception unit 17 of the sensor node 10 (step S61), the module selection unit 14 reads sensor data stored in the memory (step S62). .

  Next, the module selection unit 14 selects a module registered in advance corresponding to the type of event included in the sensor data from the module group (step S63). The analysis result generation unit 15 executes the module selected by the module selection unit 14, analyzes the sensor data, and generates an analysis result (step S64).

  Next, the determination unit 18 compares the analysis result included in the event message with the analysis result generated by the analysis result generation unit 15, and determines whether or not the two analysis results are in a similar relationship (step) S65).

  When this determination is YES (step S65; YES), the determination unit 18 determines whether or not the sensor node that has transmitted the event message is the cluster head of the cluster to which the current sensor node 10 belongs. (Step S66). When this determination is NO (step S66; NO), the message transmission / reception unit 17 transmits a withdrawal message to the cluster head of the cluster to which the current sensor node 10 belongs (step S67). Next, the message transmission / reception unit 17 returns a participation message to the sensor node that transmitted the event message (step S68). On the other hand, if it is determined in step S66 that the event message is transmitted from the cluster head of the cluster to which the current sensor node 10 belongs (step S66; YES), the process proceeds to step S68 described above. To do.

  On the other hand, when it is determined in step S65 that the two analysis results are in a dissimilar relationship (step S65; NO), the determination unit 18 determines that the sensor node that transmitted the event message belongs to the current sensor node 10. It is determined whether or not it is the cluster head of the current cluster (step S69). If this determination is YES (step S69; YES), the message transmission / reception unit 17 sends a leave message to the sensor node that transmitted the event message, that is, to the cluster head of the cluster to which the current sensor node 10 belongs. Is returned (step S70).

  In this way, a member of the temporary cluster T having an analysis result similar to the analysis result analyzed at the cluster head of the temporary cluster T can be a member of the main cluster E.

  As described above, according to the sensor network system, the cluster formation method, and the sensor node in the present embodiment, since the sensor node group having a similar relationship is determined based on the type of event and the detection time, the correlation is determined. A temporary cluster can be formed by sensor node groups that are estimated to be relatively high. In addition, based on the analysis result of the event that can determine the correlation more strictly, the node sensor group in which the analysis result is similar is determined from the sensor node group that forms the temporary cluster, This cluster can be formed by a group of sensor nodes having a high correlation. Thereby, while improving the processing efficiency at the time of collecting sensor data, the amount of traffic and power consumption in a sensor network can be reduced.

It is a figure for demonstrating the concept of the cluster formed by a some sensor node. It is a block diagram which shows the function structure of the sensor node shown in FIG. It is a flowchart for demonstrating operation | movement of the sensor node at the time of forming a temporary cluster. It is a flowchart for demonstrating operation | movement of the sensor node at the time of forming a temporary cluster. It is a flowchart for demonstrating operation | movement of the sensor node at the time of forming this cluster. It is a flowchart for demonstrating operation | movement of the sensor node at the time of forming this cluster.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Sensor node, 11 ... Sensor part, 12 ... Remaining capacity detection part, 13 ... Time management part, 14 ... Module selection part, 15 ... Analysis result generation part, 16. ··· Message generation unit, 17 ··· Message transmission / reception unit, 18 ··· Determination unit, 19 ··· Member management unit, E · ················

Claims (8)

A sensor network system having a cluster formed by one sensor node serving as a cluster head and another sensor node serving as a member,
The other sensor node is
First determination means for determining whether or not the two events are in a similar relationship based on a type and detection time of the event sensed in the other sensor node and the one sensor node;
Second determination means for determining whether or not the two events are in a similar relationship based on an analysis result of the event sensed in the other sensor node and the one sensor node,
The one sensor node is
Temporary member registration means for registering the other sensor node, which is determined by the first determination means as having a similar relationship, to a member of a temporary cluster;
The other sensor node that is registered in the temporary cluster and has been determined by the second determination means that the two events have a similar relationship is registered as a member of the cluster. A sensor network system comprising: a member registration means; The one sensor node is
Cluster head declaration distribution means for distributing a cluster head declaration including the type and detection time of the detected event after a standby time set shorter as the remaining capacity of the power supply when the event is detected increases. The sensor network system according to claim 1, further comprising: The other sensor node is
Cluster head receiving means for receiving the cluster head declaration;
Temporary cluster participation indicating that when the first determination means determines that the two events are in a similar relationship, the first sensor node that has distributed the cluster head declaration participates in a temporary cluster having the cluster head as a cluster head Provisional cluster participation message transmission means for transmitting a message to the one sensor node;
The first determination means compares the event type and the detection time detected in the other sensor node with the event type and the detection time included in the received cluster head declaration. Determine if both events are similar,
The sensor network system according to claim 2, wherein the temporary member registration unit registers the other sensor node corresponding to the temporary cluster join message with a member of the temporary cluster. The one sensor node is
Event message transmission means for transmitting an event message including an analysis result of an event detected in the one sensor node to the other sensor node registered in the temporary cluster member,
The other sensor node is
Event message receiving means for receiving the event message;
When the second determination means determines that the two events are in a similar relationship, the main cluster participation indicating that the first sensor node that transmitted the event message is to participate in the main cluster as a cluster head A cluster participation message transmitting means for transmitting a message to the one sensor node;
The second determination unit compares the analysis result of the event sensed in the other sensor node with the analysis result of the event included in the received event message, so that the two events are similar to each other. Determine if they are in a relationship,
The sensor network according to any one of claims 1 to 3, wherein the main member registration unit registers the other sensor node corresponding to the main cluster participation message with a member of the main cluster. system. The other sensor node is
A main cluster indicating that when the second determination means determines that the two events are in a dissimilar relationship, the first sensor node that has transmitted the event message leaves the main cluster as a cluster head. This cluster withdrawal message transmission means for transmitting a withdrawal message to the one sensor node;
5. The sensor network system according to claim 4, wherein the member registration unit deletes the other sensor node corresponding to the cluster withdrawal message from the members of the cluster. A method of forming a cluster having one sensor node as a cluster head and another sensor node as a member,
A first determination in which the other sensor node determines whether or not the two events are in a similar relationship based on a type and a detection time of the event sensed in the other sensor node and the one sensor node. Steps,
A temporary member registration step in which the one sensor node registers the other sensor node, in which the two events are determined to have a similar relationship in the first determination step, as a member of a temporary cluster;
Whether or not the other sensor node registered as a member of the temporary cluster has a similar relationship based on the analysis result of the event sensed by the other sensor node and the one sensor node A second determination step for determining
The member registration step of registering the other sensor node, in which the one sensor node is determined to have the similar relationship in the second determination step, as a member of the cluster;
A cluster forming method comprising: Sensor means for sensing events;
A remaining capacity detecting means for detecting a remaining capacity of a power source when an event is sensed by the sensor means;
In accordance with the remaining capacity detected by the remaining capacity detecting means, a standby time setting means for setting a shorter waiting time as the remaining capacity increases,
If the cluster head declaration that declares to become a cluster head is not received during the elapse of the standby time set by the standby time setting means, the event type sensed by the sensor means and the detection time are included. Cluster head declaration delivery means for broadcasting the cluster head declaration to other sensor nodes;
When the temporary cluster participation message indicating participation in the temporary cluster having the own sensor node as the cluster head is received from the other sensor node that has received the cluster head declaration, the other corresponding to the temporary cluster participation message Temporary member registration means for registering the sensor node as a temporary cluster member;
Event message transmission means for transmitting an event message including an analysis result of the event detected by the sensor means to the other sensor node corresponding to the member registered by the temporary member registration means;
When the present cluster join message indicating participation in the present cluster having the own sensor node as a cluster head is received from the other sensor node that has received the event message, the other cluster corresponding to the present cluster join message is received. Member registration means for registering sensor nodes as members of the cluster;
A sensor node comprising: Sensor means for sensing events;
A remaining capacity detecting means for detecting a remaining capacity of a power source when an event is sensed by the sensor means;
In accordance with the remaining capacity detected by the remaining capacity detecting means, a waiting time setting means for setting a shorter waiting time as the remaining capacity increases,
When a cluster head declaration that declares to become a cluster head is received during the elapse of the standby time set by the standby time setting means, the event type and detection time included in the cluster head declaration, and the sensor A first determination means for comparing the type and detection time of the event sensed by the means to determine whether or not the two events are in a similar relationship;
Temporary cluster participation indicating that when the first determination unit determines that the two events are in a similar relationship, the first determination unit participates in a temporary cluster having another sensor node corresponding to the cluster head declaration as a cluster head. A temporary cluster participation message transmission means for transmitting a message to the other sensor node;
Event message receiving means for receiving an event message including an analysis result of an event sensed in the other sensor node from another sensor node;
By comparing the analysis result of the event included in the event message received by the event message receiving means with the analysis result of the event sensed by the sensor means, it is determined whether or not the two events are in a similar relationship. A second determination means for determining;
This cluster participation message indicating that, when it is determined by the second determination means that the two events are in a similar relationship, the second sensor means participates in the cluster having another sensor node corresponding to the event message as a cluster head. The cluster participation message transmission means for transmitting the message to the other sensor node;
A sensor node comprising:

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