KR100921559B1 - Energy efficiency flooding method and system of wireless sensor network - Google Patents

Abstract

The present invention relates to an efficient cross layer based flooding algorithm and apparatus for solving the broadcast storm problem caused by Simple Flooding in a wireless sensor network. .

Simple flooding attempts to retransmit packets received by all nodes of the wireless sensor network, causing a broadcast strom problme that causes unnecessary energy waste due to packet collisions, inter-node packet transmission competition, and duplicate packets.

According to the present invention, identification information such as addresses of neighboring nodes in a MAC (Media Access Control) layer and received signal strength (RSS) information from neighboring nodes in a physical layer are provided by a cross-layer technique for directly accessing necessary information. And selects a retransmission candidate node capable of retransmitting the received packet among the neighboring nodes meeting the specific criterion proposed by the present invention. The neighbor node selected as the retransmission candidate node transmits the identification information of its neighbor nodes to the node to which the packet is to be transmitted, and the source node which collects the neighbor node identification information identifies its neighbor node identification information and the neighbor node of each neighbor node. The information is compared and sorted in order of the node with the most neighboring nodes that do not overlap with the source node, and the retransmission candidate nodes are ranked, and according to the network situation, the overhead and packet transmission rate and reception rate required Adjust the rate of use of retransmission candidate nodes in packet transmission to suit. In addition, the retransmission candidate node group may be stored for a predetermined time according to the moving speed and network conditions of the source node to be used when transmitting the next packet after the first packet transmission to avoid the packet overhead, delay and unnecessary energy usage generated. By this operation method, broadcast storm problem can be solved.

Flooding, broadcast storm problem, broadcasting, cross layer

Description

Energy efficiency flooding method and system of wireless sensor network

In order to solve the broadcast storm problem that causes unnecessary energy consumption by simple flooding of nodes in a wireless sensor network, the present invention directly accesses the media access control (MAC) layer and the physical layer by using a cross-layer technique and provides information on neighbor nodes. The present invention relates to a method and apparatus for energy efficient flooding in a wireless sensor network through collecting and selecting an optimal retransmission candidate node.

Unlike simple flooding, the existing flooding methods proposed to solve the broadcast storm problem select some nodes that satisfy certain criteria proposed by the corresponding flooding scheme and retransmit the received packets.

First, Received Signal Strength (RSS) refers to the strength of a received signal and can calculate the distance from the node that has transmitted the signal through this value. In free space without obstacles, the strength of the signal decreases with the square of the distance from the node transmitting the signal. Techniques related to the present invention include the following methods.

1. Distance based flooding method

In distance-based flooding, the distance from the source node is predicted by RSS, and it is determined whether the packet received by the neighbor node of the source node is retransmitted based on the calculated distance information. When the neighbor node retransmits the received packet, if the size of the region that does not overlap with the previous transmission node is greater than or equal to a specific value, the packet retransmission operation is performed.

The distance-based flooding method having such an operation method only considers the size of a newly transmitted transmission area but does not guarantee that there are a plurality of neighboring nodes that do not receive packets in the area.

2. Counter based flooding method

In the flooding method based on the number of duplicate packets received by a node, when a packet is first received, the node waits for a predetermined time and expects to receive the same packet. If a predetermined number of duplicate packets are not received during a particular time period, the node considers that there is a node among neighboring nodes in its transmission area that has not received the packet and retransmits the packet.

The flooding method based on the number of redundant packets cannot guarantee that the packets are delivered to all nodes, and the reception rate of the packets can be increased by increasing the number of redundant packets expected by the transmitting node. There is a problem that collisions increase.

3. Neighbor knowledge based flooding

Floating based on One-hop Neighbor Information and Adaptive Holding (FONIAH) using neighboring node information assumes that all network nodes know the position of neighboring nodes belonging to 1-hop, and uses the location information to determine the distance from neighboring nodes. And calculate the retransmission waiting time for the received packet according to the distance between the transmitting node and the receiving node when the packet is received. Latency is calculated shorter the farther from the node that sent the original packet, the node farthest from the transmitting node attempts to retransmit the packet first. In addition, if a duplicate packet is received during the waiting time, a node farther than itself from the original transmitting node assumes that the packet has been transmitted and abandons retransmission.

In order to operate like FONIAH, all network nodes need a separate device such as GPS (Global Positining System) to get accurate location information of themselves and neighbor nodes. There is a problem that a separate device such as GPS is difficult to use.

The present invention has been made to solve not only the broadcast storm problem by simple flooding but also the above-mentioned problems of the prior art. The identification information of neighbor nodes in the MAC layer is collected using a cross layer scheme, and each neighbor node in the physical layer is used. Gather RSS information from these fields to estimate the distance to the transmitting node. By selecting the retransmission candidate nodes capable of retransmitting the received packet by using such information and performing flooding based on the selected nodes, energy efficient flooding is performed and information of the retransmission candidate node group used in the flooding operation is networked. It saves for a certain period of time according to the situation, and adjusts the ratio of retransmission candidate nodes used for retransmission of packets to satisfy the packet reception rate and transmission rate required by various network applications. The purpose is to reduce the load on the

Energy efficient flooding method in a wireless sensor network according to the present invention for solving the above problems,

A first step of the source node collecting identification information and distance information of neighboring nodes; Exchanging a control message and a response message between the source node and the neighboring nodes to select a neighboring node having a new transmission area of a predetermined ratio or more as a retransmission candidate node; Constructing a retransmission node table by determining a rank of the retransmission candidate nodes by comparing and sorting neighbor node identification lists of the retransmission candidate nodes and neighbor node identification lists of the source node; Storing the retransmission node table, and transmitting a packet using the retransmission candidate nodes according to a predetermined retransmission node usage ratio.

In the first step, the identification information of the neighbor nodes is collected in a MAC layer using a cross layer scheme, and the received signal strength (RSS) information of the neighbor nodes is collected in a physical layer to determine distance information with the source node. Can be collected.

The control message is a message (hereinafter, referred to as a DTI message) transmitted from the source node to the neighbor nodes, and includes identification information of the source node, a sequence number of a packet to be transmitted, and a received signal strength value of a retransmission candidate node. do.

In addition, the response message is a response to the control message received by the retransmission candidate node, the identification information of the source node, the sequence number of the packet to be transmitted, the received signal strength value of the retransmission candidate node, and the A message (hereinafter referred to as DTIR message) including an identification list of neighbor nodes, wherein the DTIR message is transmitted in a unicast manner to the source node.

Also, the new transmission area of the predetermined ratio in the second step is 41% to 61% in size compared with the area transmitted by the source node, and most preferably 41%.

In the third step, the source node compares the neighboring node identification lists of the retransmission candidate nodes to obtain identification information of the retransmission candidate node (hereinafter, referred to as a first rank candidate node) having the largest number of non-overlapping neighbor nodes. After storing in the table, the list of the neighbor node identification list of the source node and the neighbor node identification list of the first rank candidate node and the neighbor node identification list of the remaining retransmission candidate nodes are compared to have the largest number of non-overlapping neighbor nodes. After storing the identification information of the retransmission candidate node (hereinafter referred to as the second rank candidate node) as the difference order of the retransmission node table, the above process is repeated for the candidate node having the third rank or less to configure the retransmission node table.

In addition, the storage of the retransmission node table in the fourth step determines the storage time of the retransmission node table in consideration of the distance from the retransmission candidate node farthest from the moving speed of the source node. At this time, the storage time of the retransmission node table is determined by the following equation.

AT = (R-d _i ) / CS

Where AT is the time to maintain the retransmission node table, R is the propagation radius of the source node, d _i is the distance of retransmission candidate node i farthest from the source node among retransmission candidate nodes, and CS is the source node Means the speed of movement.)

In addition, the predetermined retransmission node usage rate is determined by the following equation.

Equation (2): (πr ² -πd ² ) / πr ²

(Where d is the distance between the source node and the node receiving the packet, and r is the radio transmission range of the source node.)

In a fourth step of transmitting a packet by using the retransmission candidate nodes, it is preferable to transmit identification information of the neighboring node in a packet from the first rank candidate node stored in the retransmission node table.

In addition, the energy efficient flooding apparatus in the wireless sensor network according to the present invention,

A sensor node module for receiving a flooding packet; A flooding packet buffer in which a flooding packet received by the sensor node module is stored; A neighbor node management processor configured to access the sensor node module in a cross-layer manner, collect information of neighbor nodes, and configure a neighbor node table; A first memory in which the neighbor node table is stored; After checking whether the flooding packet stored in the flooding packet buffer is a received flooding packet, if the flooding packet is the first received flooding, extracts the sequence number of the flooding buffer and transmits a control message, and responds to the control message. A control message processor for receiving a; A retransmission node selector configured to perform a comparison and sort operation, select a retransmission node, and configure a retransmission node table after receiving the response message from the control message processor; A second memory in which the retransmission node table is stored; And a retransmission node table storage time determiner for calculating a reconstruction time of the retransmission node table using the speed of the source node and the neighbor node table after the retransmission node table is configured.

Further, the information of the neighbor nodes is identification information of the neighbor nodes collected in the MAC layer and received signal strength (RSS) information of the neighbor nodes collected in the physical layer.

The control message is a message (hereinafter, referred to as a DTI message) transmitted from the source node to the neighbor nodes, and includes identification information of the source node, a sequence number of a packet to be transmitted, and a received signal strength value of a retransmission candidate node. do.

In addition, the response message is a response to the control message received by the retransmission candidate node, the identification information of the source node, the sequence number of the packet to be transmitted, the received signal strength value of the retransmission candidate node, and the Message (hereinafter referred to as DTIR message) including the identification list of neighbor nodes, the DTIR message is preferably transmitted to the source node in a unicast manner.

According to the energy efficient flooding method and apparatus in the wireless sensor network according to the present invention having the above configuration,

Broadcast strom problme, which results from packet collisions caused by all nodes in the wireless sensor network attempting retransmission of packets, contention between the nodes, and waste of unnecessary energy due to duplicate packets. It is possible to solve the problem of existing distance-based flooding method, redundant packet number-based flooding method, and flooding method based on neighbor node information, and to adaptively select retransmission node to perform flooding more efficiently. It can be effective.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention; First, it should be noted that the same components or parts in the drawings represent the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the gist of the present invention.

FIG. 1 is a diagram illustrating an example of a newly transmitted area when a source B transmits a packet to a neighbor node B, and the node B retransmits a received packet. FIG. 3A illustrates a location area of neighboring nodes to which a retransmission candidate node belongs in a distance criterion determination. FIG. 3A illustrates that a source node transmits a control message to neighboring nodes for selecting a retransmission candidate node. 4 illustrates an example of transmitting a message, and FIG. 4 illustrates an example of exchanging a control message and a response message between a source node and a retransmission candidate node, and configuring a retransmission node table for a retransmission node candidate at the source node. FIG. 5 illustrates a lack of replay using a neighbor node table in a source node having a ratio of retransmission candidate nodes below the average among all neighbor nodes. 6 illustrates an example of adding a candidate node. FIG. 6 is a retransmission candidate by changing a selection criterion of a retransmission candidate node to transmit a second packet from a source node having a retransmission candidate node ratio less than or equal to a preset reference value among all neighbor nodes. FIG. 7 is a block diagram illustrating a configuration of an energy efficient flooding apparatus in a wireless sensor network according to the present invention.

In the present invention, determination of a distance criterion that may be a retransmission candidate node is as follows. In the present invention, the distance between nodes is predicted by the received signal strength (RSS) from the node. In addition, the transmission area of the previous transmission node overlaps with the transmission area of the current transmission node, and the area in which a packet is newly delivered by the current transmission node can be obtained by the following equation (1).

1, when transmitting a packet from the source node A, the air space of A _R and the packet reception node B the air space of B _R is a region of the B _R partially overlap, and this time does not overlap with A _R of the node A This node B becomes a new propagation area.

Equation (1):

Where d is the distance between nodes and r is the wireless transmission range of the node.

The maximum area where a packet is newly transmitted by the current transmitting node is when the distance between the transmitting node and the receiving node is equal to the propagation radius of the node. The size of the region is up to 61% of the area transmitted by the previous transmitting node. It has an average size of 41%.

In general, a node farther from a transmitting node may have many neighboring nodes that have not received a packet from the transmitting node, but a new transmission may not be guaranteed because a distant node has many neighboring nodes that have not received a packet. The distance between the node having a region of 41% and the source node is determined based on the selection criteria of the retransmission candidate node.

Considering various network conditions, such as having different propagation radiuses for different types of sensor nodes, a 41% new transmission range is determined to determine whether the corresponding reception node belongs to the retransmission candidate node by the distance between the transmitting node and the receiving node. There is a need for a general method for calculating the distance between a node having a transmission node and a transmitting node.

In the situation where nodes are uniformly distributed in the network area, using equation (1), the distance (d) between the transmitting node and the retransmission candidate node can be calculated as follows.

Equation (2): d = 0.65r

In order to have a transmission area of 41% or more compared to the transmission area of the previous transmitting node by equation (2), the distance between nodes must be 65% or more of the node propagation radius and the area where nodes belonging to retransmission candidate nodes are distributed by equation (2). Can be represented as shown in FIG.

Referring to FIG. 2, the area in which the retransmission candidate node is distributed is a portion in which the region D _R missing from the propagation region C _R of the node C as the distance d from the node C is a radius.

In order to know how many percent of all neighbor nodes belong to retransmission candidate nodes, the ratio of retransmission candidate nodes among all neighbor nodes should be calculated and can be calculated by Equation (3) derived from FIG.

Equation (3): (πr ² -πd ² ) / πr ²

Here, d is the distance between the source node and the node receiving the packet, r is the radio transmission range of the source node. The ratio of retransmission candidate nodes among all network nodes calculated by equations (2) and (3) is as follows.

(πr ² -π (0.65r) ² ) / πr ²

By the above equation, it can be concluded that on average, 58% of all neighbor nodes are candidates for retransmission.

The control message and response message newly defined in the present invention are as follows.

Control message Data Transmission Indication (DTI) (hereinafter, referred to as a DTI message): A control message indicating that a node having a packet to transmit to its neighbor nodes has a packet to transmit. The message includes identification information of a transmitting node and The packet includes the sequence number of the packet and the RSS value which is a distance reference of the retransmission candidate node.

Response message DTIR (Data Transmission Indication Response) (hereinafter referred to as a DTIR message): A message transmitted in a unicast manner to a transmitting node in response to a DTI message received by a retransmission candidate node. If the neighbor node that has received the DTI message has the RSS of the DTI message itself or less than the RSS value in the DTI message, the neighbor node considers itself to be included in the retransmission candidate node, and identifies the identification list of its neighbor nodes as the DTIR message. Include in and pass to source node.

As an embodiment of the energy efficient flooding method in the wireless sensor network according to the present invention, for example, a method of selecting a retransmission node in a source node having a retransmission candidate node of 58% or more is as follows.

Energy efficient flooding method and apparatus in the wireless sensor network proposed by the present invention have the same wireless transmission range of each sensor, and the sleep / wakeup period of the node is synchronized to reduce energy use efficiency and packet transmission delay using sensor-MAC. Assume that Hereinafter, an energy efficient flooding method and apparatus in a wireless sensor network according to the present invention is also referred to as a cross layer-based flooding algorithm with an adaptive retransmission node selection (FARNS).

3A and 3B illustrate a process of transmitting a control message and receiving a response message for flooding a packet using an energy efficient flooding method and apparatus in a wireless sensor network according to the present invention.

Referring to FIGS. 3A and 3B, Node 1 is a node (first node) to which a packet is to be flooded and broadcasts a DTI message to neighbor nodes for flooding. In the present invention, a neighbor node refers to a neighbor node within a communication range.

The transmission range of R _1, node 3, which in the above R _T The distance by which the retransmission candidate node selection criteria apart from, 4 and 7 of the first node is the resend candidate node, R _3, R _4, R ₇ are each retransmission It is the transmission range of the candidate node and the nodes included therein are neighbor nodes of the nodes 3, 4, and 7.

Nodes 3, 4, and 7 are nodes belonging to retransmission candidate nodes by RSS criteria, and after receiving the DTI message, transmit their neighbor node identification list to the first node in a unicast manner.

The first node receives the neighbor node identification list from the retransmission candidate nodes and performs a comparison operation, which is shown in Equation (4).

Equation (4):

In Equation (4), N is a set of neighboring nodes, s and RCN _i represent a first node and a retransmission candidate node i, respectively, and f _c is a function of counting elements of the set. The result of the comparison operation is the number of neighboring nodes that do not overlap with the first node of the retransmission candidate node i, and the result of the operation is the number of neighboring nodes that do not overlap with the first node of the retransmission candidate node. Hereinafter, the number of non-overlapping neighbor nodes is referred to as a non-overlapping neighbor node (NON).

The NONs of the retransmission candidate nodes calculated by the method according to equation (4) are sorted in descending order, and the identification information of the first-order retransmission candidate node is inserted into the retransmission node table.

Subsequent comparison and sort operations are performed by the neighbor node identification list of the retransmission candidate node inserted into the retransmission node table and the remaining retransmission candidate nodes not inserted into the retransmission node table until the last retransmission candidate node is inserted into the retransmission node table. The process of comparing and sorting the neighbor node identification list of A is repeated, and the comparison operation is shown in Equation (5).

Equation (5):

In Equation (5), RN _i means node i stored in the retransmission node table.

Through the above comparison and sorting operation, the first node selects the retransmission candidate node that has the highest number of NONs in the comparison with the first node, and in the subsequent comparison, the neighbor node identification list of the retransmission candidate node and the first node and NON selects the most nodes by comparing the neighbor node list of the nodes inserted in the retransmission node table.

After the configuration of the retransmission node table is completed, the first priority node among the nodes in the retransmission node table is flooded by a predetermined ratio considering the network situation, and the identification information of these nodes is included in the flooded packet and transmitted. In addition, the retransmission node table is stored for a predetermined time and continues to be used for that time.

If the packet includes its own identification information among the nodes that receive the flooded packet, it is regarded as being selected as the retransmission node and the packet is retransmitted by repeating the above operation.

Referring to FIG. 4, the neighbor node identification list 420 of the source node 410 is compared with the neighbor node list 440 of the retransmission candidate nodes 430 to determine the NON, and the retransmission candidate node having the largest NON. The identification information of the neighbor node identification list of the node and the source node neighbor list identification list 420 of the node stored in the retransmission node table 450 is added to the new neighbor node identification list ( 460 is created and compared with a neighbor node identification list of retransmission candidate nodes not included in the retransmission node table 450.

By the above method, the retransmission node can be selected from the source node having the retransmission candidate node of 58% or more of the total neighbor nodes, and the overhead incurred according to the ratio of using the node included in the retransmission node table in flooding. Trade-offs can be adjusted in performance, such as packet rate and packet transfer rate.

Even though the nodes are distributed evenly in the network, it may happen that the average neighboring node does not have the average retransmission candidate node. Therefore, the retransmission node is selected from the source node that does not have the average retransmission candidate node by the following method.

1. In case of transmitting the first packet, a retransmission candidate node is selected by exchanging a DTIR message with a DTI as in the retransmission node selection method.

2. The number of insufficient retransmission candidate nodes is calculated by Equation (6) in consideration of the predetermined retransmission node usage ratio and the ratio of the current retransmission candidate nodes.

Equation (6): (N _N × 0.58 × FRCN _R )-(N _N × CRCN _R )

N _N is the number-FRCN _R of the entire neighboring nodes in the formula (6) is the ratio of the retransmitted node to be used for flooding operations, CRCN _R is the ratio of the retransmission candidate node among the neighboring nodes of the first node.

3. After the first node that does not respond to the first DTI message in the neighbor node table managed by the first node is inserted into the retransmission node table to satisfy the ratio of retransmission nodes to be used for the flooding operation, the flooding operation is performed.

Referring to FIG. 5, the neighbor node table 520 is used as many as the insufficient number of retransmission candidate nodes in the current retransmission node table 510, and the completed retransmission node table 530 is configured by filling the retransmission candidate nodes.

4. From the transmission of the second packet, since the number of retransmission candidate nodes is already known, the neighbor node table is used to obtain the minimum RSS value that can fill the number of insufficient retransmission candidate nodes among the nodes that did not respond to the original DTI message. Change to the selection criteria of retransmission candidate node and transmit it in DTI message.

Referring to FIG. 6, the neighbor node table 610 is used to change the minimum RSS value that can fill the number of insufficient nodes among the nodes that do not respond to the initial DTI message to the retransmission candidate node selection criterion. In the second packet transmission, the packet is included in the DTI message 620 and broadcasted. The retransmission candidate nodes responded by the control message are stored in the retransmission node table 640 by selecting an optimal retransmission node by the compare and sort operation 630.

5. When configuration of the retransmission node is completed, the packet is flooded in the above manner and the configured retransmission table is stored for a predetermined time.

Since the selection criteria of the retransmission candidate node is changed from the transmission of the second packet, more retransmission candidate nodes can respond as expected by the first node, and the retransmission candidate that is determined to be the most efficient among the comparison and sort operations Inserts identification information of the node into the retransmission node table.

It is not necessary to use the control message defined in the present invention from the transmission of the second packet by storing the retransmission node table. As a result, it is possible to reduce the overhead of memory and processor due to packet overhead and node comparison and alignment operations, and delay. You can immediately resend a packet without

Typically, in wireless sensor networks, nodes are in fixed locations or slowly moved by separate devices. Given this situation, the storage time determination of the configured retransmission node table is defined by equation (7).

Equation (7): AT = (R-d _i ) / CS

In equation (7), AT is the time to maintain the retransmission node table, R is the propagation radius of the node, and d _i is the distance of the retransmission candidate node i farthest from the source node among the retransmission candidate nodes. In addition, CS means the moving speed of the source node.

That is, equation (7) means the time taken for the retransmission candidate node i to be out of the transmission range of the source node. However, since the source node does not know the direction of movement of node i, after this time, node i may be closer to the source node, but at a similar distance since it is calculated for the farthest retransmission candidate node. Even if the existing node is out of the transmission range of the source node, the retransmission node table may be reconfigured after the time obtained by Equation (7).

7 is a block diagram showing the configuration of an energy-efficient flooding device in a wireless sensor network according to the present invention.

The structure of the device is composed of a new functional block for the operation of the energy-efficient flooding algorithm proposed in the present invention in the general sensor node module 700.

The neighbor node management processor 710 accesses the general sensor node module in a cross layer manner, collects neighbor node information, and configures a neighbor node table in the first memory 720. In addition, when the general sensor node module 700 exchanges a periodic message with neighbor nodes, the neighbor node table is periodically reconfigured in the first memory 720 using the information of the message.

When the flooding packet is received through the general sensor node module 700, the packet is stored in the flooding packet buffer 730.

When the flooding packet received through the general sensor node module 700 is stored in the flooding packet buffer 730, the control message processor 740 checks whether the packet has already been received. Extracts the sequence number from and sends the DTI message.

In addition, when the control message processor 740 receives a DTIR message that is a response message to the transmitted DTI message, the control message processor 740 performs a comparison and sort operation for selecting a retransmission node by the retransmission node selector 750 to perform the retransmission node storage 760. Configure the retransmission node table in.

When the retransmission node table is configured in the retransmission node store 760, the retransmission node table storage time determiner 770 uses the current node speed and the neighbor node table configured in the neighbor node store 720 to reconstruct the retransmission node table. Calculate

If the ratio of retransmission candidate nodes among all neighboring nodes does not reach an average value, the control message processor 740 selects a retransmission candidate node by exchanging a DTIR message with a DTI.

Thereafter, the retransmission node selector 750 configures the retransmission node table in the retransmission node store 760 by filling up the insufficient retransmission candidate node using the neighbor node store 720.

When the time set by the retransmission node table storage time determiner 770 ends, the retransmission node table of the retransmission node storage 760 is deleted.

If another flooding packet is received by the general sensor node module 700 after the retransmission node table of the retransmission node store 760 is deleted, the control message processor 740 exchanges control messages and the retransmission node selector 750. The retransmission node table is configured in the retransmission node store 760 through the retransmission node table storage time determiner 770 and the retransmission node table reconstruction time is calculated.

An energy efficient flooding method and apparatus in a wireless sensor network according to the present invention collects neighbor node information by a cross-layer method in order to solve the broadcast storm problem by simple flooding and other flooding methods proposed in this regard. It provides a way to make energy efficient flooding.

Accordingly, the present invention selects a retransmission candidate node based on the distance information and identification information of the neighbor node collected in the wireless sensor network, and uses the neighbor node identification information of the selected retransmission candidate nodes to receive a packet by the source node. To solve the above problem by storing the list of selected retransmission nodes and continuing to use them for a certain time, as well as reducing the packet overhead and delay caused by control messages, and comparing and sorting operations. It also reduces the memory and processor load for the system.

As described above with reference to the drawings illustrating an energy efficient flooding method and apparatus in a wireless sensor network according to the present invention, the present invention is not limited by the embodiments and drawings disclosed herein, but of the present invention Of course, various modifications may be made by those skilled in the art within the scope of the technical idea.

1 is a diagram illustrating an example of a newly transmitted area when a node B retransmits a packet received when A, a source node, transmits a packet to a neighbor node B;

2 is a diagram illustrating a location area of neighboring nodes to which a retransmission candidate node belongs in determining a distance criterion for selecting a retransmission node candidate;

3A illustrates an example in which a source node transmits a control message to neighbor nodes for selecting a retransmission candidate node, and FIG. 3B illustrates an example in which the neighbor nodes transmit a response message.

4 illustrates an example of exchanging a control message and a response message between a source node and a retransmission candidate node, and configuring a retransmission node table for a retransmission node candidate at a source node;

FIG. 5 illustrates an example of adding insufficient retransmission candidate nodes using a neighbor node table in a source node having a ratio of retransmission candidate nodes below an average value among all neighbor nodes;

6 is a diagram illustrating an example of adding a retransmission candidate node by changing a selection criterion of a retransmission candidate node to transmit a second packet in a source node having a retransmission candidate node ratio less than or equal to a preset reference value among all neighbor nodes;

7 is a block diagram showing the configuration of an energy-efficient flooding device in a wireless sensor network according to the present invention.

<Description of the symbols for the main parts of the drawings>

700: sensor node module 710: neighbor node management processor

720: First memory 730: Flooding packet buffer

740: control message handler 750: retransmission node selector

760: second memory 770: retransmission node table storage time determiner

Claims (18)

A first step of the source node collecting identification information and distance information of neighboring nodes; Exchanging a control message and a response message between the source node and the neighbor nodes to select a neighbor node having a new transmission area of a predetermined ratio or more as a retransmission candidate node; Constructing a retransmission node table by determining a rank of the retransmission candidate nodes by comparing and sorting neighbor node identification lists of the retransmission candidate nodes and neighbor node identification lists of the source node; Storing the retransmission node table and transmitting a packet using the retransmission candidate nodes according to a predetermined retransmission node usage ratio; Energy efficient flooding method in a wireless sensor network comprising a. The method of claim 1, In the first step, the identification information of the neighbor nodes is collected in a MAC layer using a cross-layer scheme, and the received signal strength (RSS) information of the neighbor nodes is collected in a physical layer to collect distance information with the source node. Energy efficient flooding method in a wireless sensor network, characterized in that. The method of claim 1, The control message is a message (hereinafter, referred to as a DTI message) transmitted from the source node to the neighbor nodes, and includes identification information of the source node, a sequence number of a packet to be transmitted, and a received signal strength value of a retransmission candidate node. An energy efficient flooding method in a wireless sensor network characterized by the above-mentioned. The method of claim 1, The response message is a response to the control message received by the retransmission candidate node, and includes identification information of the source node, a sequence number of a packet to be transmitted, a received signal strength value of the retransmission candidate node, and a neighbor node of the retransmission candidate node. Message (hereinafter referred to as DTIR message), wherein the DTIR message is transmitted to the source node in a unicast manner. The method of claim 1, The new transmission area of the predetermined ratio in the second step is a size of 41% to 61% compared to the area transmitted by the source node, energy efficient flooding method in a wireless sensor network. The method of claim 1, And a new ratio of new transmission areas in a predetermined ratio in the second step is 41% larger than the area transmitted by the source node. The method of claim 1, In the third step, the neighbor node identification list of the source node and the neighbor node identification list of the retransmission candidate nodes are compared, and the retransmission candidate having the largest number of neighbor nodes that do not overlap with the neighbor node of the source node among the retransmission candidate nodes. After storing identification information of a node (hereinafter referred to as first rank candidate node) in the retransmission node table, Comparing the combined list of the neighbor node identification list of the source node and the neighbor node identification list of the first rank candidate node with the neighbor node identification list of the remaining retransmission candidate nodes, the source node and the first one of the remaining retransmission candidate nodes are compared. After storing identification information of the retransmission candidate node (hereinafter referred to as the second rank candidate node) having the largest number of neighboring nodes that do not overlap with the neighbor node of the rank candidate node as the next rank of the retransmission node table, Energy efficient flooding method in a wireless sensor network, characterized in that the retransmission node table is configured by repeating the above process for the candidate node of the third rank or less. The method of claim 1, In the storing of the retransmission node table in the fourth step, the storage time of the retransmission node table is determined in consideration of the moving speed of the source node and the distance from the retransmission candidate node farthest. Energy efficient flooding method. The method of claim 8, Energy saving flooding method in a wireless sensor network, characterized in that the storage time of the retransmission node table is determined by the following equation (1). Equation (1): AT = (R-d _i ) / CS Where AT is the time to maintain the retransmission node table, R is the propagation radius of the source node, d _i is the distance of retransmission candidate node i farthest from the source node among retransmission candidate nodes, and CS is the source node Means the speed of movement.) The method of claim 1, The predetermined retransmission node usage ratio is determined by the following equation (2). Equation (2): (πr ² -πd ² ) / πr ² (Where d is the distance between the source node and the node receiving the packet, r is the radio transmission range of the source node, and π is 3.141592) The method of claim 1, In the fourth step of transmitting a packet by using the retransmission candidate nodes, the identification information of the neighboring node is stored in the packet and transmitted from the first rank candidate node stored in the retransmission node table. Energy efficient flooding method. The method of claim 1, After transmitting the packet in the fourth step, Calculating a number of insufficient retransmission candidate nodes when the selected number of retransmission candidate nodes does not meet a predetermined reference value; A second step of inserting into a retransmission node table from a first node not responding to the DTI message of the source node in a neighbor node table managed by the source node to satisfy a ratio of retransmission nodes; A third process of changing a minimum received signal strength capable of filling the insufficient number of retransmission candidate nodes to a retransmission candidate node selection criterion and including the changed received signal strength in a DTI message to transmit a second packet; Energy efficient flooding method in a wireless sensor network further comprising. The method of claim 12, The first process of calculating the number of insufficient retransmission candidate nodes is calculated by the following equation (3). Formula (3): (N _N × 0.58 × FRCN _R )-(N _N × CRCN _R ) (N _N is the total number of neighbor nodes, FRCN _R is the ratio of retransmission nodes to be used for the flooding operation, and CRCN _R is the ratio of retransmission candidate nodes among neighbor nodes of the source node.) The method of claim 12, And selecting, by a comparison and sorting operation, retransmission candidate nodes in response to the DTI message including the changed received signal strength and storing the retransmission candidate nodes in a retransmission table. A sensor node module for receiving a flooding packet; A flooding packet buffer in which a flooding packet received by the sensor node module is stored; A neighbor node management processor configured to access the sensor node module in a cross-layer manner, collect information of neighbor nodes, and configure a neighbor node table; A first memory in which the neighbor node table is stored; After checking whether the flooding packet stored in the flooding packet buffer is a received flooding packet, if the flooding packet is the first received flooding, extracts the sequence number of the flooding buffer and transmits a control message, and responds to the control message. A control message processor for receiving a; A retransmission node selector configured to perform a comparison and sort operation, select a retransmission node, and configure a retransmission node table after receiving the response message from the control message processor; A second memory in which the retransmission node table is stored; And, After the retransmission node table is configured, a retransmission node table storage time determiner for calculating the reconstruction time of the retransmission node table using the speed of the source node and the neighbor node table. Energy efficient flooding device in a wireless sensor network comprising a. The method of claim 15, And the information of the neighboring nodes is identification information of the neighboring nodes collected in a MAC layer and received signal strength (RSS) information of the neighboring nodes collected in a physical layer. The method of claim 15, The control message is a message (hereinafter, referred to as a DTI message) transmitted from the source node to the neighbor nodes, and includes identification information of the source node, a sequence number of a packet to be transmitted, and a received signal strength value of a retransmission candidate node. An energy efficient flooding device in a wireless sensor network. The method of claim 15, The response message is a response to the control message received by the retransmission candidate node, and includes identification information of the source node, a sequence number of a packet to be transmitted, a received signal strength value of the retransmission candidate node, and a neighbor node of the retransmission candidate node. Message (hereinafter referred to as DTIR message), wherein the DTIR message is transmitted to the source node in a unicast manner.

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