KR20090084535A - Sensor network system, mobile sensor node, schedule update method for mobile sensor node - Google Patents

Abstract

A sensor network system, a mobile sensor node, a schedule update method for a mobile sensor node are provided to improve the energy efficiency and cut down data transfer delay time by supporting schedule adjustment of mobile sensor node moving within virtual clusters. A packet receiver(401) receives a sync packet from a sensor node or a boundary node belonging to each virtual cluster. The sync packet comprises schedule information. In case it moves to the boundary node from the first virtual cluster, the schedule adjuster(403) sets up the first schedule as the main part schedule. The additional second schedule which is broadcasted from the boundary node is set up as the part schedule. In this way both the first schedule and the second schedule are followed.

Description

How to update the schedule of sensor network system, mobile sensor node and mobile sensor node {SENSOR NETWORK SYSTEM, MOBILE SENSOR NODE, SCHEDULE UPDATE METHOD FOR MOBILE SENSOR NODE}

The present invention relates to a sensor network system, a mobile sensor node, and a schedule update method of a mobile sensor node.

The present invention relates to a medium access control method of a wireless sensor network, and is an efficient schedule update related technology of each sensor node.

1 illustrates a basic operation diagram of a S-MAC (S-MAC) protocol, which is a representative medium access control method of a wireless sensor network.

The S-MAC protocol repeats the operation of turning on and off the sensor node's transceiver in the wireless sensor network (called 'Listen') and turning it off (called "sleep") so that the transceiver does not participate in the communication. It is a representative MAC protocol for wireless sensor networks that increases energy efficiency by reducing energy waste caused by turning on (called "idle listening").

This protocol's multiple approach uses Carrier Sensing Multiple Access / Collision Avoidance (CSMA / CA), such as the IEEE 802.11 standard, and reserves channels through the exchange of Request To Send (RTS) and Clear To Send (CTS) packets. To prevent collisions in advance. In the listen section of the S-MAC protocol, a section for transmitting SYNC packets carrying schedule information, a section for control packets of RTS and CTS, and a section for transmitting a DATA packet are set.

Data transmission of the S-MAC protocol is transmitted after the RTS and CTS exchanges between two nodes are sent and received.In this case, the data transmission may be completed in the listen interval depending on the packet length of this data, and the length of the data to be transmitted is long. In the sleep period, data transfer may be continued.

On the other hand, due to the development of wireless communication and microelectronics technology, a network of low-cost, ultra-small sensors is possible, and this wireless sensor network has intelligent transportation system, automatic control of production process, warehouse logistics management, ecological environment monitoring, etc. It can have a variety of applications.

Particularly in the recent application field of wireless sensor network, in wireless sensor network, such as sensor device attached to patient for remote diagnosis of patient condition in hospital, sensor device provided for safety to people working in dangerous industrial field There is an increasing demand for applications that require the mobility of sensor nodes.

In general, the profile of the S-MAC protocol is designed based on the assumption that there is no mobility, that is, a static situation, after the deployment of the sensor node. . This is because in the S-MAC protocol, each sensor node periodically repeats listen-sleep cycles and schedules listen-sleep cycles with each other for communication with neighbor nodes. .

In the S-MAC protocol, the transceiver is periodically turned on for a long time to register and recognize sensor nodes having completely different schedules as neighbor nodes. This is called periodic neighbor discovery.

By listening to each sensor node for a long time, each sensor node can receive a sync packet broadcast by a sensor node with a completely different schedule, thereby finding and rescheduling neighbor nodes with different schedules. In this process, when the sensor node receives a sync packet of a schedule different from its own schedule, the sensor node additionally listens for another schedule. At this time, the determination of any one schedule is performed by removing the schedule if no sync packet associated with the schedule being followed is received for a certain time.

However, the regular neighbor search process takes a long time to listen, which can lead to large energy consumption, so the S-MAC protocol is supposed to do it every few minutes. At this point, if the periodic neighbor search time interval is set short, energy consumption is increased, but the schedule can quickly update other neighbor nodes, and if the regular neighbor search time interval is long, the energy consumption is reduced but the schedule is different. There may be a delay in updating.

That is, the setting of the regular neighbor node search time interval may form a tradeoff between the energy consumption of the node and the update time delay of the neighbor nodes having different schedules.

In an application of a wireless sensor network in which the mobility of sensor nodes is frequently moved, a sensor node that belongs to one virtual cluster and follows a schedule associated with the same moves to another virtual cluster. Since these sensor nodes have different schedules than the sensor nodes belonging to the moved virtual cluster, they are temporarily isolated until they are registered as neighbor nodes through regular neighbor search and the schedule is adjusted. Therefore, if you try to deliver data to these nodes, there is a problem that the packet is not delivered along with the delivery delay.

In other words, the mobility support of the S-MAC protocol using the conventional method in a mobile application has a performance limitation.

Therefore, the technical problem to be achieved by the present invention is to reduce the delay in data transmission and improve the efficiency of energy consumption by quickly supporting the scheduling of mobile sensor nodes moving between virtual clusters.

According to an aspect of the present invention, there is provided a sensor network system including: a first virtual cluster including a sensor node sharing a first schedule, and a second virtual cluster including a sensor node sharing a second schedule; It may include a boundary node belonging to the first virtual cluster and the second virtual cluster and complying with both the first schedule and the second schedule.

In addition, a mobile sensor node according to an embodiment of the present invention for achieving the above technical problem, a first virtual cluster including a sensor node sharing a first schedule, a second virtual including a sensor node sharing a second schedule A mobile sensor node moving in a sensor network comprising a cluster and a boundary node located between the first virtual cluster and the second virtual cluster and following both the first schedule and the second schedule, the mobile sensor node belonging to each virtual cluster. When the packet receiver receives the sync packet including the schedule information from the sensor node or the border node and moves from the first virtual cluster to the border node, the first schedule is broadcasted from the border node as the main schedule. By setting an additional second schedule as a sub schedule, the first schedule and It may include a schedule adjuster that follows all of the second schedule.

And the schedule update method of a mobile sensor node according to an embodiment of the present invention for achieving the technical problem, the first virtual cluster including a sensor node sharing a first schedule, a sensor node sharing a second schedule A method of updating a schedule of a mobile sensor node moving in a sensor network including a second virtual cluster and a boundary node positioned between the first virtual cluster and the second virtual cluster and following both the first schedule and the second schedule. The method may include: a) receiving a sync packet of the edge node; b) setting a first schedule that was originally followed as a main schedule, and setting a second schedule included in the sync packet of the edge node as a sub-schedule. have.

As described above, according to the present invention, the mobility of the sensor node can be supported by utilizing the sync packet information of the edge node in the wireless sensor network, and thus, a gain can be obtained in various aspects.

First, the data transmission delay time can be reduced. When the mobility support method using the sync packet of the boundary node is executed, when the data is transmitted to the moving sensor node, the schedule update is performed immediately when the data is transferred to another virtual cluster, and thus the data is not delivered while waiting for the periodic neighbor search. Can be prevented. Therefore, according to the present invention, the data transmission delay time is reduced.

In addition, in the case where the moving sensor node receives the sync packet of the boundary node and completely sets up the listen interval of the additional schedule, the receiving sensor node receives only the sync packet including one schedule before fully determining its schedule with one schedule. Data can be received even in the listen section of the additional schedule, which shows excellent performance in terms of data transmission delay.

Second, data transfer throughput can be increased. When sending data to a moving sensor node, a fast schedule update at the time of transitioning to another virtual cluster enables data delivery to the moving node. This improves the throughput, reducing the number of undelivered packets being discarded, resulting in performance improvements in data throughput.

In addition, when the sensor node receives the sync node's sync packet and completely configures the listen interval of the additional schedule, and receives the sync packet and the sync packet including one schedule at the same time, the sync includes one schedule. The method of setting the schedule of the packet as the primary schedule, before going into the virtual cluster and receiving only the sync packet including one schedule without receiving the sync packet of the boundary node, completely determines the schedule of the mobile node with one schedule. The data can be received in the listen section of the additional schedule, which shows excellent performance in terms of data delivery throughput.

Third, the mobile sensor node receives the sync packet of the edge node and listens to the additional schedule in the update process through the sync packet of the edge node, thereby performing a schedule update, and receiving only the sync packet having only one schedule. The time required to determine a schedule as a single schedule is considerably shorter than a schedule update process through a conventional regular neighbor search.

In addition, when receiving the sync packet of the edge node and updating the schedule, the method of setting only the sink section for the additional listen period also improves energy consumption by taking the listen in the additional schedule. Improves.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

When a part of the specification 'includes' a certain component, this means that it may further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms 'unit', 'unit', 'module', etc. described in the specification mean a unit for processing at least one function or operation, which may be implemented by hardware or software, or a combination of hardware and software.

Now with reference to the drawings with reference to the embodiment of the present invention will be described in detail.

2 is a diagram illustrating a configuration of a sensor network system and a schedule of each node according to an embodiment of the present invention.

Each sensor node decides its listen-sleep schedule after being deployed. It monitors whether a sync packet containing schedule information is transmitted from a neighbor node for a certain period of time. It works on its own schedule on the listen-sleep schedule. In this case, if the sink packet is not received for a predetermined time, the scheduler arbitrarily sets its own schedule and broadcasts the information in the sink packet.

The schedule determination method of the sensor nodes generates a set of sensor nodes whose schedules are synchronized with each other, which is called a virtual cluster. Here, different virtual clusters generally follow different schedules (101, 201), and sensor nodes in the same virtual cluster share the same schedule.

At the junction between the virtual clusters, sensor nodes belonging to several virtual clusters exist. These sensor nodes are referred to as boundary nodes 301. The boundary nodes located at junctions between different virtual clusters operate according to all listen-sleep schedules 301 of the virtual clusters to which they belong to transfer sensing data between the virtual clusters.

The listen section is a section to send and receive sync packets containing schedule information (SYNC section), and a CSMA / CA type Request To Send (RTS) and CTS (Clear To) to prevent signal collisions in a transmission medium. Section for the control packet of the Send (RTS, CTS section) and the transmission section of the data packet transmitted after the exchange of these control packets (DATA section), depending on the length of the data packet in the listen section (listen) The data transmission may be terminated in the case of the data transmission, and when the length of the data to be transmitted is long, the data transmission may be continued by using the sleep interval.

The boundary node 300 follows the schedules 101 and 201 of the virtual cluster 1 (100) and the virtual cluster 2 (200), thereby enabling data transfer between both clusters.

3 is an overall configuration diagram of the wireless sensor network, and illustrates a situation in which the mobile sensor node 400 belonging to the virtual cluster 1 100 moves and approaches the boundary node 300. The mobile sensor node 400 follows the same schedule as the schedule of the sensor nodes belonging to the virtual cluster 1 (100), and the sensor nodes belonging to the virtual cluster 2 (200) have different schedules from the virtual cluster 1 (100). . In addition, the boundary nodes 300 operate while following the schedules of the virtual cluster 1 (100) and the virtual cluster 2 (200).

Here, the movement direction of the mobile sensor node 400 approaches scenario 1 (10) passing through the boundary node 300 and the boundary node 300 and enters into the virtual cluster 1 (100) again in scenario 2 (20). ) Situation is possible.

The mobile sensor node 400 follows the schedule of the virtual cluster 1 (100), and receives the additional schedule information from the boundary node 300 near the boundary node 300, and thus the virtual cluster 1 (100) and the virtual cluster 2 (200). When all the schedules are followed and completely moved into the virtual cluster 2 (200), the schedule update is determined by the schedule of the virtual cluster 2 (200).

In addition, the mobile sensor node 400 follows the schedule of the virtual cluster 1 (100), and receives additional schedule information from the boundary node 300 near the boundary node 300 to the virtual cluster 1 (100) and the virtual cluster 2 ( After all the schedules of 200 are moved to the virtual cluster 1 (100) again, the schedule update is determined by the schedule of the virtual cluster 1 (100).

4 is a configuration diagram of a mobile sensor node.

As illustrated, the mobile sensor node 400 includes a packet receiver 401, a schedule adjuster 403, a schedule execution unit 405, a storage unit 407, and a schedule broadcaster 409, and have different schedules. It moves between virtual clusters and performs a schedule update according to a schedule belonging to each cluster.

The packet receiver 401 may receive a SYNC packet including schedule information from a sensor node or a boundary node belonging to each virtual cluster.

If a sync packet including schedule information is received from the neighboring node, the schedule adjusting unit 403 may adjust its own schedule to the listen-slip schedule of the neighboring node.

The schedule adjuster 403 follows the schedule 1 when the mobile sensor node 400 belongs to the virtual cluster 1, and then, from the warning node 300 when the mobile sensor node 400 is located near the boundary node 300. Schedule 2 additionally included in the transmitted sync packet may be reflected as a schedule.

When the mobile sensor node 400 moves inside the virtual cluster 2, the schedule adjusting unit 403 may determine the schedule 2 which is the schedule of the virtual cluster 2 as the final schedule.

The schedule adjusting unit 403 may arbitrarily set its own schedule when receiving a sync packet from neighbor nodes for a predetermined time.

The schedule execution unit 405 may transfer the data by repeating the listen-sleep cycle according to the schedule adjusted by the schedule adjustment unit 403.

The storage unit 407 may store the received packet information and may store the schedule information of the mobile sensor node 400.

The schedule broadcaster 409 may broadcast its own schedule information in a sync packet. If the schedule information is not received from a neighbor node for a predetermined time, the schedule broadcaster 409 may also broadcast randomly designated schedule information in the sync packet.

5 is a flowchart of a schedule update operation for supporting mobility of a mobile sensor node according to an embodiment of the present invention.

First, in order to support mobility of a sensor node, the sync packet of the boundary node 300 may broadcast schedule information of all virtual clusters to which the sync node belongs in a sync packet.

When the mobile sensor node 400 moves and approaches the border node 300, the mobile sensor node 400 may receive a sync packet broadcast by the border node 300 (S100).

The mobile sensor node 400 may additionally include an additional schedule included in the sync packet of the boundary node 300 separately from the schedule it was originally following (hereinafter, referred to as a 'primary schedule') (hereinafter, referred to as a 'secondary schedule'). schedule), the schedule update may be performed by performing a listen (S103).

At this time, when receiving the sync packet from the boundary node 300, the mobile sensor node 400 may operate by following only the main schedule, which is its own schedule (S101).

The mobile sensor node 400 may receive a sync packet from the boundary node 300 to perform a schedule update, and the mobile sensor node 400 may move away from the boundary node 300. At this time, the sink packet of the sensor node belonging to only one virtual cluster, that is, following only one schedule may be received (S105).

In this situation, if the mobile sensor node 400 receives the sync packet of the boundary node 300 together, it may mean that the mobile sensor node 400 is still staying near the boundary node 300. Therefore, the previous main schedule and the sub schedule can be kept as they are, or the previous main schedule and the sub schedule can be changed (S109, S111).

In this case, the mobile sensor node 400 may receive a sync packet of a schedule other than the schedule originally followed by receiving a sync packet of the boundary node 300 and listening to an additional schedule. .

In case of changing the previous main schedule and the sub schedule, the mobile sensor node 400 is located near the boundary node 300 but is closer to a virtual cluster, and the schedule related to the virtual cluster is set as the main schedule. This is to prepare for schedule adjustments.

In this case, if the sink packet of the boundary node 300 is not received and the sink packet including only one schedule is received, the mobile sensor node 400 has moved out of the boundary node 300 and entered into a specific virtual cluster. It means. Therefore, the mobile sensor node 400 may determine and adjust its own schedule with a schedule related to a sync packet including one schedule (S113).

If the mobile sensor node 400 stays around the boundary node 300 and continues to receive the sync packet of the boundary node 300, it cannot listen to a single schedule and listen for both the main schedule and the sub schedule. It can be maintained (S107).

The schedule update method for supporting mobility of the mobile sensor node as described above may be applied to three types of embodiments, and details thereof will be described later.

As shown in FIG. 6, when the mobile sensor node 400 receives the sync packet of the boundary node 300 according to the first embodiment of the present invention, the schedule 601 originally followed by the mobile sensor node 400. Instead of the additional schedule 602, that is, the listen interval of the secondary schedule, the listener may be configured to only listen to the interval for receiving the sync packet, and the mobile sensor node 400 may include only one schedule. You can keep this until you only receive packets and decide on a schedule.

According to the first embodiment, there is an advantage that energy consumption can be reduced by using a listen interval of a sub-schedule only for receiving a sync packet.

7 is a schedule update method of a mobile sensor node according to a second embodiment of the present invention.

As shown, the mobile sensor node 400 receives the sync packet of the boundary node 300 so that the additional schedule 702, i.e., the sub-schedule, is not the first schedule 701 that the mobile sensor node 400 originally followed. The listen interval of may be configured to listen only for a period for receiving a sync packet.

When the mobile sensor node 400 is simultaneously receiving the sync packet of the boundary node 300 and the sync packet of the sensor node having one second schedule near the boundary node 300, the mobile sensor node 400 receives the second schedule 702. The primary schedule and the first schedule 701 may be set as sub schedules. The mobile sensor node 400 knows which virtual cluster it belongs to based on the boundary node 300, and determines the virtual cluster. You will most likely follow the schedule, so be prepared for this.

At this time, like the sub schedule, the first schedule 701 may be set to listen only in a section for receiving a sync packet in a listen section for energy efficiency.

Next, when the mobile sensor node 400 receives only the sync packet including only one schedule, the mobile sensor node 400 may determine its own schedule as the one schedule.

According to the second embodiment, by knowing in advance which virtual cluster the mobile sensor node 400 belongs to while setting the energy efficiency for the listen section of the additional schedule, and setting the schedule of the virtual cluster as the main schedule, It can quickly receive the data transmitted from the sensor node of the virtual cluster. Therefore, it is excellent in terms of transmission delay and energy efficiency.

8 is a schedule updating method of a mobile sensor node according to a third embodiment of the present invention.

As illustrated, when the mobile sensor node 400 receives the sync packet of the boundary node 300, the mobile sensor node 400 adjusts the schedule by completely setting a listen interval of the additional schedule.

The mobile sensor node 400 following the first schedule 801 of the virtual cluster 1 listens to the second schedule 802 of the additional virtual cluster 2 when receiving the sync packet of the boundary node 300. do.

At this time, the additional updated second schedule 802 is also required to have a complete listen interval, so that data transmission delay can be prevented when data is delivered from the sub-schedule before the schedule is determined.

9 is a diagram illustrating a process of determining a schedule by a mobile sensor node 400 having adjusted a schedule according to a first embodiment of the present invention by receiving a sync packet having one sync information.

FIG. 9A illustrates a schedule determination process of the mobile sensor node 400 when following scenario 1 of FIG. 3.

That is, the mobile sensor node 400 receives the sync packet of the boundary node 300, and the first schedule 911 of the virtual cluster 1 and the second schedule 912 of the virtual cluster 2 are the main schedule and the sub schedule, respectively. As a result, the mobile sensor node 400 receives only the sync packet broadcast from the sensor node having only the second schedule 912 when fully passed into the virtual cluster 2.

At this time, the mobile sensor node 400 may determine only the second schedule 912 as its own schedule and perform adjustment.

FIG. 9B is a diagram illustrating a schedule determination process of the mobile sensor node 400 when following scenario 2 of FIG. 3.

That is, when the mobile sensor node 400 receives the sync packet of the boundary node 300 and operates while following the first schedule 921 and the second schedule 922, the mobile sensor node 400 returns to the virtual cluster 1. 400 receives only sync packets broadcast from the sensor node having only the first schedule 921.

At this time, the mobile sensor node 400 may determine its own schedule and adjust by only the first schedule 921.

10 is a diagram illustrating a process of determining a schedule by a mobile sensor node 400 having adjusted a schedule according to a second embodiment of the present invention by receiving a sync packet having one sync information.

10A and 10B illustrate a process of determining a schedule by the mobile sensor node 400 according to scenario 1 of FIG. 3.

That is, as shown in (a) of FIG. 10, the mobile sensor node 400 receives the sync packet of the boundary node 300 and operates while following the first schedule 1011 and the second schedule 1012. When entering the virtual cluster 2, the mobile sensor node 400 simultaneously receives the sync packet of the boundary node 300 and the sync packet of the sensor node having the second schedule 1012.

At this time, the mobile sensor node 400 changes its main schedule and sub schedule so that the first schedule 1011 is a sub schedule and the second schedule 1012 is a main schedule.

As shown in FIG. 10B, when the mobile sensor node 400 moves further to receive only the sync packet broadcast from the sensor node having only the second schedule of the virtual cluster 2, the mobile sensor node 400 receives the first packet. Only the schedule 1102 can determine its own schedule and adjust.

10 (c) is a diagram illustrating a process of determining a schedule by the mobile sensor node 400 when following scenario 2 of FIG. 3.

That is, as shown, when the mobile sensor node 400 receives the sync packet of the boundary node 300 and operates along the first schedule 1021 and the second schedule 1022 and returns to the virtual cluster 1, Since the sync packet associated with the virtual cluster 2 has not been received, the first schedule 1021 may be maintained as the main schedule and the second schedule 1022 may be maintained as the sub schedule.

Then, when the mobile sensor node 400 continues to move and enters into the virtual cluster 1, the mobile sensor node 400 receives only the sync packet broadcast from the sensor node having the schedule of the virtual cluster 1, and the mobile sensor node 400 The first schedule 1021 of the virtual cluster 1 may be determined as its own schedule and adjusted.

FIG. 11 is a process diagram in which the mobile sensor node 400 receives only a sync packet having one schedule information and determines a schedule according to the third embodiment of the present invention.

FIG. 11A illustrates a case in which the mobile sensor node 400 follows scenario 1 of FIG. 3.

That is, the mobile sensor node 400 receives the sync packet of the boundary node 300 and operates along the first schedule 1111 of the virtual cluster 1 and the second schedule 1112 of the virtual cluster 2, and then moves to the virtual cluster 2. In case of skipping, only the sync packet broadcasted from the sensor node having the second schedule 111 2 of the virtual cluster 2 is received. At this time, the mobile sensor node 400 schedules its own schedule using only the second schedule 1112. You can confirm and make adjustments.

FIG. 11B illustrates a case in which the mobile sensor node 400 follows scenario 2 of FIG. 3.

That is, the mobile sensor node 400 receives the sync packet of the boundary node 300 and operates along the first schedule 1121 of the virtual cluster 1 and the second schedule 1122 of the virtual cluster 2, and then returns to the virtual cluster 1. When returning, the mobile sensor node 400 may receive only the sync packet broadcast from the sensor node having only the first schedule 1121, and may determine and adjust the schedule using only the first schedule 1121.

12 is a graph comparing the data propagation delay of the scheme proposed by the present invention and the conventional scheme.

As shown, the data propagation delays 1210, 1215 and 1220 according to the first, second and third embodiments of the present invention are compared with the conventional data propagation delays 1205.

The shorter the packet generation period, the greater the difference in data propagation delay, and the third and second embodiments of the present invention are superior to the data propagation delay of the first embodiment. It can be seen that it is superior to the transfer delay 1205.

13 is a graph comparing the data transfer throughput of the scheme proposed by the present invention and the conventional scheme.

As shown, the data transfer throughput of the first, second, and third embodiments 1310, 1315, and 1320 of the present invention was compared with the data transfer throughput of the conventional method 1305.

It can be seen that the third embodiment and the second embodiment are superior to the data transfer throughput in the case of the first embodiment, and the three schemes according to the present invention are superior to the data transfer throughput of the conventional scheme 1305 as a whole. .

14 is a graph comparing the energy consumption efficiency of the method proposed by the present invention and the conventional method.

As shown, the energy consumption of the first, second and third embodiments 1410, 1415, 1420 of the present invention is compared with that of the mobile sensor node 400 of the conventional scheme 1405. It was.

In the case of the second embodiment and the first embodiment according to the present invention, the energy consumption efficiency (1410, 1415, 1420) of the three methods proposed by the present invention is superior to the third embodiment. It can be seen that it is superior to the energy efficiency of (1405).

15 is a graph comparing the energy consumption efficiency of each packet transmitted according to the method proposed by the present invention and the conventional method.

As shown, the energy consumption of the mobile sensor node 400 per delivered packet of the first, second and third embodiments 1510, 1515, 1520 of the present invention and that of the conventional scheme 1505 The energy consumption of the mobile sensor node 400 per packet delivered was compared.

In the case of the second embodiment and the first embodiment according to the present invention, the energy consumption efficiency per packet delivered is superior to that of the third embodiment. It can be seen that the efficiency is excellent.

What has been described above is only an embodiment of the present invention, and the scope of the present invention is not limited thereto, and various modifications can be made to those skilled in the art. For example, the nodes included in the sensor network system and the components constituting the nodes may be additionally configured or merged according to their function.

In addition, the schedule update method of the mobile sensor node according to an embodiment of the present invention, of course, can be configured so that the order is changed.

The scope of the present invention will include all the technical elements recognized as the claims described below and equivalents thereof.

1 is a basic operation diagram of a protocol in a sensor network.

2 is a block diagram of a sensor network system including a virtual cluster and a boundary node according to an embodiment of the present invention.

3 is a diagram illustrating a moving scenario of a mobile sensor node according to an embodiment of the present invention.

4 is a block diagram of a mobile sensor node according to an embodiment of the present invention.

5 is a method for updating a schedule of a mobile sensor node according to an embodiment of the present invention.

6 to 8 illustrate a method for updating a schedule according to the first, second and third embodiments of the present invention.

9 to 11 are diagrams illustrating a method of updating a schedule according to a first embodiment, a second embodiment, and a third embodiment when a mobile sensor node moves according to scenario 1 or scenario 2.

12 to 15 are graphs comparing the data transmission delay, data transmission rate, energy consumption efficiency, and energy consumption efficiency per packet delivered according to the prior art and the exemplary embodiment of the present invention.

Claims (19)

In the sensor network system, First virtual cluster including sensor nodes sharing a first schedule A second virtual cluster comprising sensor nodes sharing a second schedule and A boundary node belonging to the first virtual cluster and the second virtual cluster, the boundary node following both the first schedule and the second schedule; Sensor network system. The method of claim 1, The boundary node is located at a junction point of the first virtual cluster and the second virtual cluster, and is in a listen state for both a listen section of the first schedule and a listen section of the second schedule. Taking Sensor network system. A first virtual cluster including a sensor node sharing a first schedule, a second virtual cluster including a sensor node sharing a second schedule, and positioned between the first virtual cluster and the second virtual cluster A mobile sensor node moving in a sensor network including a boundary node that follows both a schedule and the second schedule, A packet receiver configured to receive a sync packet including schedule information from the sensor node or the boundary node belonging to each virtual cluster; When moving from the first virtual cluster to the border node, The first schedule is set as a main schedule, and an additional second schedule broadcasted from the border node is set as a sub schedule, and includes a schedule adjusting unit that follows both the first schedule and the second schedule. Mobile sensor node The method of claim 3, The schedule adjustment unit The schedule is adjusted to listen only for the sync packet reception interval for the listen interval of the sub-schedule. Mobile sensor node The method of claim 4, wherein The schedule adjustment unit, When moving to the second virtual cluster and receiving only the sync packet of the sensor node having the second schedule, Adjusting only the second schedule to a final schedule Mobile sensor node. The method of claim 3, The schedule adjustment unit, Listen for only the sync packet reception interval for the listen interval of the sub-schedule, When the mobile station moves to the second virtual cluster and simultaneously receives the schedule information broadcast from the edge node and the sync packet of the sensor node having the second schedule, Adjusting the first schedule to a sub schedule and the second schedule to a main schedule Mobile sensor node The method of claim 6, The schedule adjustment unit, When receiving only a sync packet having the second schedule Determining the second schedule as a final schedule Mobile sensor node The method of claim 3, The schedule adjustment unit Adjusting a schedule to take a listen for the entire listen interval of the main schedule and the sub schedule. Mobile sensor node. The method of claim 8, The schedule adjustment unit, When moving to the second virtual cluster and receiving only the sync packet of the sensor node having the second schedule, Adjusting only the second schedule to a final schedule Mobile sensor node. A first virtual cluster including a sensor node sharing a first schedule, a second virtual cluster including a sensor node sharing a second schedule, and positioned between the first virtual cluster and the second virtual cluster; 1. A method of updating a schedule of a mobile sensor node moving in a sensor network including a boundary node following both a first schedule and a second schedule, a) receiving a sync packet of the border node b) setting the first schedule that was originally followed as the main schedule and a second schedule included in the sync packet of the edge node as a sub schedule. How to update schedule. The method of claim 10, Step b), The sub-schedule is configured to listen on only the sync packet reception interval. How to update schedule. The method of claim 11, After step b), c) moving to the second virtual cluster and receiving only the sync packet of the sensor node having the second schedule, adjusting only the second schedule to a final schedule; How to update schedule. The method of claim 11, After step b), d) returning to the first virtual cluster, when receiving only the sync packet of the sensor node with the first schedule, adjusting only the first schedule to a final schedule; How to update schedule. The method of claim 10, Step b), In a listen interval of the sub-schedule, a listen is performed only for a sync packet reception interval; e) when the sync packet of the sensor node having the second schedule and the schedule information broadcasted from the boundary node is moved toward the second virtual cluster at the same time, Adjusting the first schedule as a sub schedule and the second schedule as a main schedule. How to update schedule. The method of claim 14, After step e), f) when receiving only the sync packet having the second schedule, determining the second schedule as a final schedule How to update schedule. The method of claim 14, After step b), g) determining the first schedule as a final schedule when moving toward the first virtual cluster to receive only the sync packet of the sensor node having the first schedule; How to update schedule. The method of claim 10, Step b), Adjusting a schedule to take a listen for the entire listen interval of the main schedule and the sub schedule; How to update schedule. The method of claim 17, After step b), h) when moving to the second virtual cluster and receiving only the sync packet of the sensor node having the second schedule, adjusting the second schedule only to the final schedule; How to update schedule. The method of claim 17, After step b), i) returning to the first virtual cluster, when receiving only the sync packet of the sensor node with the first schedule, adjusting only the first schedule to a final schedule; How to update schedule.

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