KR101364705B1 - Method and System of Network Management for Mitigating Congestion in Wireless Sensor Network - Google Patents

Abstract

The present invention relates to a network management method for reducing congestion by distributing traffic in a wireless sensor network. According to the present invention, a gateway having a large free buffer size and excellent traffic / packet capacity according to the arrangement of sensor nodes in a cluster may be selected as a bypass gateway. In addition, in the present invention, the bypass gateway can accommodate a node / traffic from a cluster of congested gateways within a range where congestion does not occur. This enables more sophisticated network management by intelligently managing traffic between the central server and each gateway.

Description

Method and system for reducing congestion on wireless network {Method and System of Network Management for Mitigating Congestion in Wireless Sensor Network}

The present invention relates to a network management system, and more particularly, to a network management system and a network management method in which a central server and a gateway cooperate in a wireless sensor network to reduce traffic congestion and enable stable packet transmission.

The present invention has been derived from the research conducted by Yuhan-hwan as a part of the broadcasting and telecommunication development project of the Korea Communications Commission and the Korea Communications Agency and the IT Convergence Advanced Human Resource Support Project of the Ministry of Knowledge Economy and the Korea Information and Communications Industry Promotion Agency [1. Assignment Management No. 11913-04005, Assignment Name: Development of WiBro / LTE based M2M terminal standard platform, 2. Assignment Management No .: NIPA-2011-C6150-1101-0004, Assignment Name: IT Machine Convergence Center].

The sensor network is a sensor node that has a sensing capability, an information processing capability for processing the sensed information, and a communication capability for transmitting information, and collects information from the sensor node to the outside. It consists of exported sink nodes. A sensor network operated by a wireless communication method is called a wireless sensor network (WSN).

Unlike conventional networks, sensor networks are based on automated remote information collection rather than means of communication, and are widely used for various purposes such as scientific, medical, military, and commercial purposes.

Recently, wireless sensors have emerged in the market and are emerging as a valid tool that can replace the existing wired network, and the approach to the sensor network is developing into a new phase. Wireless sensor networks are less space constrained, allowing a wider range of applications. As the demand for the wireless sensor network increases, there is a need for a routing technology that can reliably manage the packets of the increasing wireless sensor network. Based on the wireless sensor network, generally, the routing method of the sensor network considers the entire area of the network as a single space, and the flat routing and multi-hop routing divides the network area into several cluster units, and one cluster. In particular, a specific node may be selected as a head node, and may be divided into hierarchical routing in which a head node is routed around the head node.

As such, a routing technique for smoothing packet traffic in a cluster-based sensor network has been attempted in Korean Patent Registration No. 10-1038543 "Routing Method in Sensor Network".

According to the prior art, the nodes in the sensor network form a cluster in a predetermined range, and select a cluster head representing the cluster. A cluster head discloses a configuration for collecting information of nodes in a cluster and transmitting the collected information to a sink node. In this way, a hierarchical routing scheme using the energy of the node is possible.

However, even in accordance with the prior art, if the traffic is concentrated in a specific cluster or a specific sink node, there is a problem that the stability of the network is greatly reduced. Therefore, it is necessary to develop an intelligent network management system that can solve the traffic concentration.

Korea Patent Registration No. 10-1038543

Recently, as the demand for ubiquitous service increases, the development of wireless sensor network technology is accelerating. Wireless sensor network is a core technology of ubiquitous network and can be applied to various applications. However, since a large number of sensor nodes in a sensor network must be installed, there are limitations in using relatively inexpensive hardware devices. Therefore, due to the characteristics of the sensor node using limited hardware performance and low network bandwidth, it is necessary to develop an efficient and intelligent management method for the network system in order to expand the wireless sensor network to more diverse applications.

As a management technique of wireless sensor network, stable distributed use of rapidly increasing packets has been the focus of MAC protocol and routing protocol design, and many related studies are being conducted.

Wireless sensor networks play a role in monitoring and collecting information in complex environments on behalf of humans. Sensor nodes used in wireless sensor networks are limited in applications due to limited hardware performance and low wireless network bandwidth usage. In order to use sensor node stably, research is needed to make the best use of low performance.

Accordingly, it is necessary for the sensor node to manage the network without directly performing many data processing or operations other than the sensing function. As an alternative thereto, the present invention provides a border gateway for managing a plurality of sensor nodes on a cluster basis. , XBG) and Central Server (CS) intelligently cooperate to manage the network.

An object of the present invention is to provide a network management system for stably managing an entire network by distributing traffic in a wireless sensor network.

In order to achieve the above object, the present invention is composed of a central server (CS) and a plurality of border gateways (XBG). In this case, the border gateways have a concept similar to a sink node or a sink end, and include a buffer that can store incoming data packets and a processor that can operate on cluster information. can do.

The central server identifies each congested gateway by periodically receiving respective congestion degrees from a plurality of gateways on the wireless sensor network or by receiving a message indicating that congestion has occurred. In this case, the congestion degree may be a parameter indicating a possibility of congestion at each gateway, and may be based on a ratio of input / output packets monitored at each gateway.

At this time, the central server designates a neighboring gateway adjacent to the identified congested gateway as a search range and requests neighboring gateways within the search range about the available buffer size and packet capacity, and receives the result value from the neighbor gateways. can do.

At this time, if the available buffer size and packet capacity do not satisfy the condition of the central server, the central server requests and receives the available buffer size and packet capacity information from neighbor gateways within the extended range by expanding the search range of neighbor gateways. You may. If the available buffer size and packet capacity information received from one or more neighboring gateways satisfy the conditions set in advance by the central server, the central server selects the one or more neighboring gateways as bypassable gateways for congested gateways. do.

In this case, the central server may select a neighbor gateway having a large available buffer size and excellent packet capacity according to the arrangement of sensor nodes in the cluster as the bypass gateway of the first priority.

In this case, when the congestion of the congested gateway is not solved by only the bypass gateway of the first priority, the neighbor gateway of the second priority selected based on the available buffer size and the packet capacity of the cluster may be added as the bypass gateway.

The central server notifies the bypass gateway that it has been selected as the bypass gateway. The selected bypass gateway can extend the range of the cluster by progressively accepting sensor nodes from congested gateways.

The gateway periodically updates the state of the gateway to the central server so that the central server can identify which congestion has occurred at which gateway.

In addition, the gateway checks the available buffer size and the packet capacity of the cluster periodically or at the request of the central server, and sends them to the central server. The central server can use this information to select which of the neighbor gateways of the crowded gateways to designate as the bypass gateway.

The bypass gateway notified that the bypass gateway has been selected as the bypass gateway expands the range of the cluster by accommodating a part of the sensor nodes of the congested gateway in a range where congestion of the bypass gateway does not occur. In some embodiments, the bypass gateway may notify the central server of information related to the range of the newly expanded cluster.

According to the present invention, the central server and each gateway intelligently manage traffic / packets in cooperation with each other, thereby enabling more stable and sophisticated network management than the conventional technology.

In addition, the bypass gateway is selected in consideration of the geographical or geometrical factor according to the arrangement of sensor nodes managed by each gateway, thereby effectively distributing traffic without burdening all neighboring gateways. .

In addition, each gateway accommodates sensor nodes managed by a gradually crowded gateway to accommodate traffic / packets of the crowded gateway, thereby minimizing additional traffic overhead to manage traffic and managing the network in a distributed form. Can be.

Accordingly, the present invention provides a military surveillance system that requires stable network management, a surveillance system through multimedia such as wireless video and audio, a storage system for predicting activities of criminals or automobile accidents, a system for traffic control, health care or the elderly. It can be widely used in areas such as auxiliary systems in homes and sensor networks for home networks or intelligent buildings.

In addition, when combined with intelligent video surveillance technology, it is possible to comprehensively monitor fires in subways, intrusion into restricted areas, and passenger congestion.

1 is a diagram illustrating a wireless sensor network system according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating criteria for determining packet capacity of a cluster that can be executed in the system of FIG. 1.
3 is a diagram illustrating each step and subject of a network management method that may be executed in the system of FIG. 1.
4 is an operational flow diagram illustrating an embodiment of a network management method that may be executed by gateways 121, 122, and 123 of the system of FIG. 1.
FIG. 5 is an operational flow diagram illustrating one embodiment of step S460 of FIG. 4 in more detail.
6 is an operational flowchart illustrating an embodiment of a network management method that may be executed by the central server 110 of the system of FIG. 1.
FIG. 7 is an operational flow diagram illustrating one embodiment of step S640 of FIG. 6 in more detail.
FIG. 8 is an operational flowchart showing in more detail an embodiment of step S630 of FIG. 6.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings.

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

However, the present invention is not limited to or limited by the embodiments. Like reference symbols in the drawings denote like elements.

The present invention relates to a network management system, and more particularly, to a network management system and a network management method invented for the purpose of reducing traffic congestion and enabling stable packet transmission in cooperation with a central server and a gateway in a wireless sensor network. will be.

According to the present invention, a central server (CS) and a plurality of border gateways (XBGs) intelligently manage packets in cooperation with each other, rather than the conventional wireless sensor network system, so that the network management is more stable and sophisticated than conventional technologies. There is an advantage to this.

1 is a diagram illustrating a wireless sensor network system 100 according to an embodiment of the present invention.

As shown in FIG. 1, the wireless sensor network system 100 according to the present invention includes a central server 110 and a plurality of border gateways 121, 122, and 123.

The central server 110 periodically receives the states of the plurality of border gateways 121, 122, and 123, and when a crowded gateway occurs, selects a bypassable neighboring gateway to select the plurality of border gateways 121, 122, 123).

In FIG. 1, it is assumed that congestion has occurred in the gateway 123.

In addition, the plurality of border gateways 121, 122, and 123 correspond to one cluster 131, 132, and 133, respectively, and the information of sensor nodes in the corresponding clusters 131, 132, and 133 is referred to as a central server. On the other hand, it manages the state of the sensor nodes.

The sensor node 141 transmits sensing information about the surrounding environment to the central server 110 via the gateways 121, 122, and 123, and whether each sensor node is normally operated (the person commonly referred to as "survival"). Also may be transmitted to the central server 110 via the gateways 121, 122, and 123.

Short-range communication is performed between the sensor nodes 141 and the gateways 121, 122, and 123 in the clusters 131, 132, and 133, and long-distance communication between the gateways 121, 122, 123 and the central server 110. This is done. The gateways 121, 122, and 123 include a telecommunication device capable of performing telecommunication with the central server 110.

Each of the gateways 121, 122, and 123 includes a data buffer capable of storing incoming data packets. Each of the gateways 121, 122, and 123 has an input rate of data packets flowing into the data buffer per unit time and a service rate at which data packets stored in the data buffer are processed or serviced per unit time. By comparison, each congestion parameter can be calculated. In this case, the service rate is generally a value that is difficult to change. The higher the input rate, the higher the congestion of the gateway.

That is, as an embodiment, when the input rate is higher than the service rate, congestion may be regarded as occurring at the corresponding gateway. In some embodiments, congestion may be considered even when the input rate is 90% or 80% or more of the service rate.

The plurality of border gateways 121, 122, and 123 periodically update the congestion degree to the central server 110, or transmit a congestion generation message to the central server 110 when congestion occurs.

The central server 110 may identify the congested gateway 123 by using the received congestion of the plurality of border gateways 121, 122, and 123.

The central server 110 receives the available buffer size of the border gateways 121, 122, and 123 and the packet capacity of the cluster (a cluster corresponding to each gateway). In this case, each of the border gateways 121, 122, and 123 may periodically transmit the available buffer size and the packet capacity of the cluster to the central server 110, or, if there is a request from the central server 110, available buffers. The size and packet capacity of the cluster may be transmitted to the central server 110.

That is, in the first embodiment, all the plurality of border gateways 121, 122, and 123 may calculate the congestion, the available buffer size, and the packet capacity of the cluster and periodically transmit them to the central server 110. In the second embodiment, all of the plurality of border gateways 121, 122, and 123 periodically transmit congestion to the central server 110, and after the central server 110 identifies the congested gateway, It may also request the neighbor's neighbor's available buffer size and packet capacity.

In the third embodiment, all of the plurality of border gateways 121, 122, and 123 may monitor the congestion degree and notify the central server 110 of congestion when congestion occurs in the gateway 123.

The central server 110 selects a bypassable neighbor gateway using available buffer sizes received from all or some (at least one) of all the plurality of border gateways 121 and 122 and the packet capacity of the cluster. A notification informing that the bypass gateway selected by the central server 110 is selected may be transmitted.

The neighbor gateway selected as the bypass gateway extends the cluster by increasing the hop distance to accommodate the sensor nodes of the cluster of the congested gateway. As a result, the bypass gateway receives the traffic of the congestion gateway, and the congestion degree of the congestion gateway is lowered. Bypass gateways can extend the scope of the cluster by accepting sensor nodes from congestion gateways, as long as congestion does not occur on their own. The bypass gateway may inform the central server 110 of the extent of the extended cluster.

For example, if congestion is identified at the gateway 123, the central server 110 selects one of the neighbor gateways 121 and 122 as a bypass gateway, or both of the neighbor gateways 121 and 122. Can be selected as the bypass gateway.

At this time, if the gateway 121 is selected as the bypass gateway, the gateway 121 extends the range of the corresponding cluster 131 by one hop distance, thereby traffic from the cluster 133 corresponding to the congested gateway 123. It can accommodate some sensor nodes.

FIG. 2 is a diagram illustrating an embodiment of a packet capacity of a cluster 131 and 132 corresponding to each of the plurality of border gateways 121 and 122 of the present invention. The method for calculating the packet capacity shown in FIG. 2 is a method applicable to all of the first to third embodiments of FIG.

The gateways 121 and 122 calculate the packet capacity of the clusters 131 and 132 using the arrangement or distribution of sensor nodes in the corresponding clusters 131 and 132, respectively.

Referring to FIG. 2, there is provided a diagram illustrating the number of sensor nodes with the same hop depth from XBG 121 corresponding to the hop depth. That is, the vertical axis is the hop depth from the XBG 121, and the length of the horizontal axis is the number of sensor nodes corresponding to each hop depth.

Sensor nodes in the cluster 131 may be divided based on hop-depth from the XBG 121. That is, in the cluster 131, the side where the hop distance from the XBG 121 is close is divided into the core region 131a, and the side where the hop distance from the XBG 121 is far away is divided into the peripheral region 131b. The packet capacity of the cluster 131 may be determined by comparing sensor nodes of the core region and the peripheral region 131b (periphery region).

When the number of sensor nodes in the core region 131a is larger than the number of sensor nodes in the peripheral region 131b, the cluster 131 may be healthy and the packet capacity may be large. Accordingly, in FIG. 2, the cluster 131 is healthier than the cluster 132 and has a larger packet capacity. This is because the number of sensor nodes in the peripheral region 132b is larger than the core region 132a of the cluster 132.

An embodiment of a parameter that can evaluate the packet capacity of the cluster 131 as one parameter may be calculated as follows. The maximum value of the number of sensor nodes corresponding to the hop distance with the XBG 121 in the peripheral area 131b is set as a reference value, and the sensor node corresponding to the hop distance with the XBG 121 in the core area 131a. The packet capacity of the cluster 131 is calculated by using the ratio of the number of 141 and the set reference value.

More specifically, the minimum value among the number of sensor nodes corresponding to the hop distance in the core region 131a may be set as a comparison target. A possibility of bottlenecks may be predicted according to the ratio between the set reference value and the set comparison target. That is, the section in which the number of sensor nodes corresponding to the hop distance in the core region 131a has the smallest number is the choke point, and the section most likely to cause bottlenecks.

When the number of sensor nodes of the choke point is smaller than the set reference value (maximum value of the number of sensor nodes in the peripheral areas 131b and 132b), or smaller than 90%, 80%, 70%, etc. of the set reference value. The clusters 131 and 132 may be evaluated as unhealthy. XBG (121, 122) may provide a ratio of the set reference value and the number of sensor nodes of the choke point as a measure of packet capacity for the cluster (131, 132), the calculated ratio is 100%, 90% The result of the determination as to whether the number exceeds 80%, 70%, or 60% may be provided as a measure of packet capacity with a value of 0 or 1. 100%, 90%, 80%, 70%, or 60%, which is the basis of the determination, may be determined according to a network management policy, and may be shared by all XBGs and central servers 110 and CS, and each XBG. It may be set differently for.

Since the packet capacity of the cluster 131 is higher than that of the cluster 132 in FIG. 2, in FIG. 1, the central server 110 is a bypass gateway for supporting a congestion gateway 123 in which congestion occurs. The gateway 121 corresponding to 131 may be selected.

3 is a conceptual diagram illustrating a network management scheme in which a central server 110 and a plurality of border gateways 121, 122, and 123 cooperate with each other in a wireless sensor network 100 according to a second embodiment of the present invention. It is shown. 3 is a diagram showing each step of performing the network management method according to the second embodiment of the present invention and the subject thereof.

Referring to FIG. 3, the central server 110 receives congestion of the plurality of border gateways 121, 122, and 123 periodically from the plurality of border gateways 121, 122, and 123 (S310). Identifies the gateway (S320). The central server 110 requests the available buffer size and the packet capacity of the cluster corresponding to the neighboring gateway to the neighboring gateway around the identified congested gateway 123 (S330), thereby providing a plurality of border gateways 121 and 122. ) Receives the available buffer size and the packet capacity of the cluster calculated from some or all (S340).

The central server 110 selects a bypassable neighbor gateway using the available buffer size received from all or part of the plurality of border gateways 121 and 122 and the packet capacity of the cluster (S350), and the plurality of border gateways. The gateways selected as bypasses of the gateways 121 and 122 may be notified that the gateways are selected as bypass gateways (S360). The selected gateway among the plurality of border gateways 121 and 122 may extend the range of the cluster corresponding to the gateway (S370) and notify the central server 110 of the extended range (S380).

4 is a flowchart illustrating an operation of a network management method (network management method for alleviating traffic congestion) executed by a plurality of border gateways 121, 122, and 123 in the wireless sensor network system 100 of the present invention. 4 is an operation flowchart applicable to the first or second embodiment of FIG.

The plurality of border gateways 121, 122, and 123 periodically update their state to the central server 110 (S410). In this case, when congestion occurs in the gateway 123, the central server 110 may identify it. Each gateway (121, 122) checks its available buffer size and transmits it to the central server (110) (S430) calculates the packet capacity of the clusters (131, 132) and transmits to the central server (110) S440). At this time, all the gateways 121 and 122 may transmit the available buffer size and the packet capacity to the central server 110 (first embodiment), and only the gateway requested from the central server 110 may use the available buffer size. It is also possible to transmit the packet capacity to the central server 110 (second embodiment).

After receiving a notification indicating that the neighboring gateway has been selected as a bypassable neighbor gateway from the central server 110 (S450), the selected gateway extends the scope of the cluster (S460). The selected gateway checks its congestion level and gradually reduces congestion already occurring by accepting sensor nodes and traffic of congested gateways within the congestion-free range.

FIG. 5 is an operational flow diagram illustrating one embodiment of step S460 of FIG. 4 in more detail. Referring to FIG. 5, the hop_depth currently set in the selected gateway 121 or 122 is increased by 1 to generate new_hop_depth (S510). The gateway 121 or 122 checks whether congestion occurs based on new_hop_depth (S520). At this time, whether the congestion may be confirmed by simulation of new_hop_depth, or congestion may be checked by accepting traffic from the sensor node by temporarily applying new_hop_depth.

If the selected gateway increases the hop distance to accommodate the congested traffic but the congestion does not occur at the selected gateway itself, the selected gateway has enough capacity to accommodate the congested traffic, and thus replaces the existing hop_depth with new_hop_depth (S530). The hop_depth is increased by one again (S510).

If the selected gateway increases the hop distance and congestion occurs in the selected gateway itself, since the selected gateway does not have enough capacity to accommodate the congested traffic, discard the new_hop_depth (S540) and maintain the existing hop_depth. The gateway 121 or 122 may notify the central server 110 of the current hop_depth (S550).

6 shows an operational flow of an embodiment of a network management method executed in the central server 110 on the wireless sensor network 100 of the present invention. FIG. 6 is an operational flowchart applicable to the first or second embodiment of FIG. 1.

The central server 110 periodically receives each state from the plurality of border gateways 121, 122, and 123 (S610). In this case, the state information may be a parameter indicating congestion or a message indicating that congestion has occurred.

The central server 110 identifies the gateway in which congestion occurred using the congestion degree or congestion message (S620).

The central server 110 receives the available buffer size and the packet capacity of the cluster from at least one gateway (S630), and the bypassable neighbor that can support the congestion gateway by using the received available buffer size and the packet capacity of the cluster. A gateway is selected (S640).

At this time, in the first embodiment, step S630 also receives information from all the gateways 121, 122, 123. Meanwhile, in the second embodiment, the available buffer size and the packet capacity of the cluster are requested to neighboring gateways around the congested gateway before step S630, and the available buffer size and the packet capacity of the cluster are received from the requested neighbor gateways ( S630).

FIG. 7 is a flowchart illustrating a process of selecting bypassable neighbor gateways according to an embodiment of step S640 of FIG. 6.

The central server 110 may select the neighboring gateway of the first priority as the bypass gateway in consideration of the available buffer size received in step S630 and the packet capacity of the cluster (S710).

In this case, the central server 110 may give a first priority to neighboring gateways having a large available buffer size and a large packet capacity of the cluster. The criterion of prioritization is the available buffer size and the packet capacity of the cluster, and one of the available buffer size and the packet capacity of the cluster may be preferentially applied to the other depending on the routing environment. Alternatively, the priority may be determined by assigning separate weights to the available buffer size and the packet capacity of the cluster.

The central server 110 designates and notifies the neighboring gateway of the first priority as the bypass gateway, and checks whether congestion of the congestion gateway is eliminated by the operation of the bypass gateway (S720). At this time, the congestion cancellation may be determined after a certain time elapses, or the congestion gateway may be requested to recalculate the congestion degree.

If the congestion is resolved, the central server 110 may end the sequence and return to step S610.

If the congestion of the congested gateway is not resolved, the central server 110 adds a neighbor gateway of the second priority to the bypass gateway in consideration of the received available buffer size and the packet capacity of the cluster.

The criteria that the central server 110 gives the neighboring gateway a second priority may be the same as or different from that of the first priority. The bypass gateway, which has been given a second priority, also expands the cluster in the same way as the gateway of the first priority to partially accommodate traffic and sensor nodes of the congested gateway.

By this process, if the congestion is not resolved, the central server 110 may add neighbor gateways of lower priority as additional bypass gateways.

8 is a flowchart illustrating an operation of searching for a bypassable neighbor gateway according to an embodiment of step S630 of FIG. 6. FIG. 8 is an operation flowchart corresponding to the second embodiment of FIG. 1.

The central server 110 designates neighboring gateways adjacent to the congested gateway identified in step S620 as the primary search range (S810).

The central server 110 may request available buffer size and packet capacity information from neighbor gateways designated as the primary search range (S820).

The central server 110 receives the available buffer size and the packet capacity of the cluster from neighbor gateways designated as the primary search range (S830).

The central server 110 determines whether there is a neighbor gateway that satisfies a preset condition in consideration of the available buffer size of the received neighbor gateways and the packet capacity of the cluster (S840).

At this time, if there is a neighbor gateway where the available buffer size and the packet capacity of the cluster satisfy the condition of the bypass gateway, the central server 110 selects them as the bypass gateway (S640).

If a neighbor gateway that satisfies the condition of the available bypass size and the packet capacity of the cluster as the preset bypass gateway does not exist within the first search range, the search range of the neighbor gateway is expanded (S850).

In step S850, the available buffer size of the other neighboring gateways within the second search range expanded and the packet capacity of the cluster are requested (S820), and the available buffer size and the packet capacity of the cluster are determined from neighboring gateways within the second search range. Receive (S830).

In this way, a searchable gateway can be searched from neighboring gateways from a crowded gateway, and the search range can be gradually increased when there is no suitable gateway.

Network management method that can be executed in the central server 110 or each gateway (121, 122, 123) according to an embodiment of the present invention is implemented in the form of program instructions that can be executed by various computer means computer readable media Can be recorded. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

As described above, the present invention has been described by specific embodiments such as specific components and the like. For those skilled in the art, various modifications and variations are possible from these descriptions.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

100: wireless sensor network system
110: central server (CS)
121, 122, 123: Border Gateway (XBG)
131, 132, 133: cluster
141: sensor node
131a and 132a: core region
131b and 132b: peripheral region

Claims (13)

A plurality of gateways each corresponding to one cluster, the plurality of gateways confirming each congestion degree; And
A central server for receiving the congestion from the plurality of gateways to identify congested gateways;
Lt; / RTI >
At least one or more of the plurality of gateways calculates each available buffer size and the packet capacity of the corresponding cluster to send to the central server,
The central server selects a bypassable neighbor gateway corresponding to the identified congested gateway using the available buffer size and the packet capacity,
At least one of the plurality of gateways calculates the packet capacity using a distribution of sensor nodes in the cluster corresponding to each of the plurality of gateways. The method of claim 1,
The selected neighbor gateway increases the range of the cluster corresponding to the neighbor gateway by one hop within a range where congestion does not occur. delete The method of claim 1,
At least one of the plurality of gateways calculates the packet capacity using the number of sensor nodes corresponding to a hop distance with each gateway in the corresponding cluster. The method of claim 1,
And each of the plurality of gateways calculates the congestion degree using the number of packets flowing into the buffer per unit time and the number of packets in the buffer that can be processed per unit time. Calculating a congestion degree for the gateway and transmitting it to the central server;
Checking the available buffer size of the gateway and transmitting it to the central server;
Calculating packet capacity of the cluster using the distribution of sensor nodes in the cluster corresponding to the gateway and transmitting the packet capacity of the cluster to the central server; And
When the gateway is selected as a bypassable neighbor gateway from the central server, increasing the range of the cluster by one hop within a range where congestion does not occur
/ RTI > The method according to claim 6,
Computing the packet capacity
And calculating the packet capacity using the number of sensor nodes corresponding to a hop distance with the gateway in the cluster. The method according to claim 6,
Computing the packet capacity
Dividing a side in which the hop distance from the gateway is close to a core region in the cluster and a side in which the hop distance from the gateway is far from a peripheral region;
Setting a maximum value of the number of sensor nodes corresponding to a hop distance with the gateway in the peripheral area as a reference value; And
Calculating a packet capacity of the cluster using a ratio of the number of sensor nodes corresponding to the hop distance with the gateway and the reference value in the core region;
/ RTI > The method according to claim 6,
Calculating the congestion degree
And calculating the congestion degree using the number of packets entering the buffer in the gateway per unit time and the number of packets that can be processed in the buffer per unit time. Receiving, by a central server, congestion of each of the plurality of gateways from the plurality of gateways;
Identifying, by the central server, the congested gateway using the congestion degree;
The central server receiving an available buffer size and packet capacity of a cluster from at least one of the plurality of gateways; And
The central server selecting a bypassable neighbor gateway corresponding to the identified congested gateway using the received available buffer size and the packet capacity of the cluster
Lt; / RTI >
The central server receiving the available buffer size and the packet capacity of the cluster
Accepting the packet calculated by each of at least one of the plurality of gateways using a distribution of sensor nodes in the cluster corresponding to each of at least one or more of the plurality of gateways from at least one or more of the plurality of gateways Network management method of receiving capability. The method of claim 10,
Selecting the bypassable neighbor gateway by the central server
The central server designating gateways within a first distance from the identified congested gateway as a first candidate gateway;
Confirming, by the central server, the packet capacity of the cluster and the available buffer size calculated by the first candidate gateway with respect to the first candidate gateway; And
If there is no first candidate gateway where the available buffer size and the packet capacity of the cluster meet a preset condition, the central server selects a second candidate gateway within a second distance from the identified congested gateway. Steps to Specify as a Gateway
/ RTI > The method of claim 10,
Selecting the bypassable neighbor gateway by the central server
Prioritizing, by the central server, the neighboring gateways around the identified congested gateways using the available buffer size calculated by each of the neighboring gateways and the packet capacity of the cluster; And
Selecting, by the central server, some of the neighbor gateways as the bypassable neighbor gateway in preference to the remaining neighbor gateways according to the assigned priority.
/ RTI > A computer-readable recording medium in which a program for executing the method of any one of claims 6 to 12 is recorded.

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