KR101503076B1 - The method for detouring hole in position-baced routing and sensor node using said method - Google Patents

Abstract

The present invention provides a method of efficiently bypassing the hole by setting a landmark around the hole when a hole exists in the greedy forwarding-based routing protocol, and a sensor node using the method. The present invention can transmit data through a smaller number of nodes than a conventional routing technique by transmitting data from a transmission node to a destination node via a node set as the landmark. This minimizes routing overhead and improves the energy efficiency of the routing protocol.

Routing, location-based routing protocol, Greedy forwarding scheme, Perimeter forwarding scheme

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a method of routing information in a wireless communication system,

The present invention relates to a routing technique in a wireless sensor network, and more particularly, to a method of setting an optimal routing path by bypassing a hole in a greedy forwarding routing technique.

The proposed routing protocol in the sensor network can be divided into three major data-centric-based, hierarchical-based, and location-based protocols. The sensor network is very important because it can be used as meaningful data to know the location of actual data.

A typical example of a location-based routing protocol is the Greedy Perimeter Stateless Table (GPRS) technique. The GPRS is a technique developed for location-based routing in Ad-hoc networks. There are Greedy forwarding scheme and Perimeter forwarding scheme in GPRS scheme, which is a location based routing protocol. The greedy forwarding scheme refers to a method of transmitting a packet to a node closest to a destination node among nodes that the node can transmit. For this purpose, each node periodically exchanges position information with neighboring one-hop nodes, so that all nodes manage the position information of their one-hop nodes in a table.

In the greedy forwarding scheme, it is determined that there is a hole when the distance to the destination node of the neighboring node is less than the distance to the destination node of the neighboring node, and a method of bypassing the hole is tried.

A typical method of bypassing the hole is the Perimeter forwarding technique disclosed in FIG. The Perimeter forwarding scheme is a method in which a node that receives a packet finds the next node clockwise using the right-hand rule. That is, when routing is performed using the perimeter forwarding scheme, the nodes around the hole calculate the distance to the destination node and the distance between the neighbor node and the destination node, and then find the next node to be transmitted.

However, when the Perimeter forwarding method is used, unnecessary transmission is caused by passing through several nodes around the hole to transmit data. The unnecessary transmission causes routing overhead, and reduces energy efficiency of the routing protocol by causing more energy consumption.

Therefore, a routing technique for solving the above-mentioned problems and increasing the energy efficiency of the routing protocol is desperately required.

The present invention provides a method and a sensor node that can efficiently bypass the hole by setting a landmark around the hole in the presence of holes in a location based routing protocol.

A routing method for bypassing holes in a location based routing protocol, the method comprising: receiving a data packet from a neighboring node and confirming a transmission mode of the received data packet; Comparing the distance between the neighboring node and the destination node to the distance between the root node and the destination node when the transmission mode is the Perimeter forwarding mode; Selecting a routing method for transmitting the data packet to a next node based on the compared distance and calculating a size of the hole when there is a neighbor node closer to the distance from the destination node to the root node And generating a hole probe packet for setting a landmark by comparing the calculated hole size with a preset threshold value.

According to another aspect of the present invention, there is provided a landmark setting method for bypassing a hole in a location based routing protocol, the method comprising: receiving a hole probe packet from a neighboring node; Confirming whether the address of the root node included in the received hole probe packet matches the node address of the node; When the address of the root node and the node address of the node do not coincide with each other, the left landmark position and the node position of the own probe packet are in the same direction with respect to the straight line connecting the root node and the destination node A process of determining whether or not to: A step of updating a position of a left landmark and a right landmark of the hole probe packet based on the determination, and a step of forwarding a hole probe packet including position information of the updated landmark to a next node A landmark setting method for detouring a landmark is provided.

In the present invention, when a hole exists in a location-based routing protocol, a node located at an outermost node among the nodes around the hole is set as a landmark, and data is transmitted from the transmission node to the destination node via the node set as the landmark It is possible to transmit data via a smaller number of nodes than conventional routing schemes. This minimizes routing overhead and improves the energy efficiency of the routing protocol.

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. The following terms are defined in consideration of the functions of the present invention, and these may be changed according to the intention of the user, the operator, or the like. Therefore, the definition should be based on the contents throughout this specification.

The present invention proposes a scheme for effectively bypassing the hole by setting a landmark around the hole when a hole exists in the greedy forwarding-based routing protocol. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

2 illustrates a configuration of a sensor node according to an embodiment of the present invention.

Referring to FIG. The sensor node 200 includes a control block 202, a greedy forwarding block 204, a perimeter forwarding block 206, and a landmark setting block 208. Those skilled in the art will appreciate that the blocks may be implemented in hardware or software as part of the sensor node 200.

When the control block 202 receives the data packet from the neighboring node, the control block 202 determines whether the destination node address recorded in the p.dID field of the received packet matches its node address. If the destination node address and the node address of the destination node match, the packet is transmitted to the upper layer. However, if the destination node address does not match its own node address, routing is performed to forward the packet to the next node.

 The control block 202 confirms the presence of a landmark when performing the routing. If there is a landmark, the landmark is set to the temporary destination address and Greedy forwarding is performed.

However, even if the sensor node (or the transmitting node 200) receives the information on the landmark and knows the existence and location of the landmark, the sensor node (or the transmitting node 200) does not necessarily use the landmark. This is because the use of the landmark is determined depending on the location of the transmission node. Any landmark will be a usable landmark if it is a landmark that can bypass the hole between itself and the sink node, otherwise it will be a meaningless landmark.

FIG. 3 illustrates landmark areas that may be used in accordance with an embodiment of the present invention, and FIG. 4 illustrates locations of nodes and landmarks according to an embodiment of the present invention.

Referring to FIGS. 3 and 4, a transmitting node uses a function S (p1, p2, line) to determine whether the landmark is a landmark to be passed through when sending a packet to a sink node. Here, the function S (p1, p2, line) is a function for checking whether two points p1 and p2 exist in the same direction with respect to the line. The function S (p1, p2, line) outputs a value of 1 if the two points p1 and p2 belong to the same area in two areas where the line distinguishes, and a value of -1 otherwise.

 In FIG. 4, F indicates the position of the transmission node, S indicates the position of the sink node, and d indicates a straight line connecting the right landmark and the left landmark. That is, the function S (F, S, d) is a function for checking whether the transmitting node F and the sink node S are in the same direction with respect to the straight line d connecting the two landmarks. Similarly, S (R, L, l) is a function to check whether two landmarks (R, L) are in the same direction based on a straight line (l) The function S can be derived by the following formula.

The function S (R, L, I) can also be calculated using the above equation.

The above two equations are used to determine whether or not the landmark is used in the transmitting node. That is, the transmission node and the sink node exist in different directions with respect to the straight line connecting the two landmarks, and the two landmarks must exist in different directions based on the straight line connecting the transmission node and the sink node. The above condition can be expressed by the following formula.

S (F, S, d) = -1

S (R, L, I) = -1

After confirming that the landmark is a usable landmark, the transmitting node sets the temporary destination address of the packet to the position of the node set as the landmark. Thereby, the transmitting node can bypass the hole by the shortest distance by transmitting the packet to the sink node via the landmark. If there is no landmark necessary for the user, the landmark setting block 210 sets the landmark.

Meanwhile, when routing is performed, the control block 202 determines whether or not there is a neighbor node nearest to the destination node, that is, whether there is a hole.

If there is no hole, the control block 202 executes the greedy forwarding block 206. That is, the transmitting node transmits a packet to a neighboring node that is closer to the destination node than the neighboring node itself.

However, if there is a hole, the control block 202 operates the Perimeter Forwarding Block 206 and the Landmark Set Block 208. That is, the control block 202 confirms the presence of the hole and selects a routing method according to the size of the hole. Here, the selection of the routing method according to the size of the hole may be performed by the landmark setting block 208. When the size of the hole is small, perimeter forwarding having a low complexity is used because the number of nodes existing around the hole is small. In the case of a hole having a value larger than a threshold value, a routing method is used in which a landmark is set around the hole to bypass the hole .

The Greedy forwarding block 204 performs a function of selecting a node having a shortest path to a destination node from neighboring nodes and transmitting the packet.

The Perimeter Forwarding Block 206 is a function that uses the right-hand rule to bypass a hole and transmit a packet when there is no neighboring node that is closer than the distance between the node and the destination node among the neighboring nodes .

When the size of the hole is equal to or greater than the threshold value, the landmark setting block 210 sets a landmark around the hole and informs the nodes within a predetermined hop of the surrounding landmark do. In addition, the landmark setting block 210 provides a function to bypass the hole by setting the position of the node set as the landmark to the temporary destination address when the position of the destination node has to go across the hole .

As described above, the sensor node according to the present invention transmits a packet to a neighboring node having a shortest path by using Greedy forwarding scheme, which is a location-based routing scheme. However, when there is no neighboring node having the shortest path, that is, when there is a hole, the perimeter forwarding method is used according to the size of the hole, or the hole bypassing method using the landmark setting is used.

Figure 5 shows a flow diagram of a routing scheme according to a preferred embodiment of the present invention.

Referring to FIG. 5, in step 502, a forwarding node receives a data packet from a neighboring node.

In step 504, the transmitting node determines whether the destination node address recorded in the p.dID field of the received packet matches its own node address. If the destination node address and its own node address match, the flow advances to step 506 to transmit the received packet to an upper layer. However, if the destination node address does not match its own node address, That is, when the received packet is not a packet received from the transmitting node, the transmitting node performs a forwarding function and transmits the forwarding function to the next node.

In step 508, the transmission node checks whether a landmark exists. If the landmark is detected, the process moves to step 510. In step 510, the transmission node confirms whether the landmark is a usable landmark. If it is determined that the landmark is usable, the transmitting node sets the address of the temporary destination node to the address of the node set as the landmark.

When the step 510 is completed, the transmitting node performs greedy forwarding after moving to step 516.

If the landmark is not detected, the process proceeds to step 512. In step 512, the transmitting node determines whether the forwarding mode of the received packet is a greedy forwarding mode. If the transmission mode is Greedy forwarding, the process proceeds to step 514.

In step 514, the control block determines whether there is a hole by checking whether there is a neighboring node whose distance from the destination node is closer than that of the neighboring node itself. If there is no hole, the process moves to step 516. In step 516, the transmitting node forwards the packet to the next node through Greedy forwarding routing. However, if there is a hole, the flow advances to step 518 to perform perimeter forwarding.

If it is determined in step 512 that the transmission mode is set to the Perimeter forwarding mode, the flow advances to step 520.

In step 520, the control block determines whether greedy forwarding can be applied at the current location. That is, the distance between the neighboring nodes and the destination node is compared with the distance between the root node and the destination node to determine whether there is a neighboring node that is closer than the distance between the root node and the destination node. Here, the root node refers to a node that performs perimeter forwarding first among the nodes around the hole when there is a hole.

If there is a neighboring node that is closer than the distance between the root node and the destination node among the neighboring nodes, In step 522, the transmitting node converts the packet transmission mode from the perimeter forwarding mode to the greedy forwarding mode, and then performs Greedy forwarding. The transmitting node then sets a landmark in step 526. [ A detailed description of the landmark setting method will be described later.

If there is no neighbor node that is closer than the distance between the root node and the destination node in step 520, the packet transmission mode is maintained in the existing Perimeter forwarding mode. In step 524, the Perimeter forwarding is performed do.

Through the above process, the transmitting node can select the optimal routing path and transmit the packet to the next node.

Hereinafter, the hole sensing method and the landmark setting method will be described in detail.

FIG. 6 shows a flow chart of a hole sensing method according to an embodiment of the present invention, and FIG. 7 shows a root node and a transmission node according to an embodiment of the present invention.

Referring to FIG. 6, in step 602, a forwarding node receives a data packet from a neighboring node. In step 604, the transmitting node determines whether the forwarding mode of the received packet is a Greedy forwarding mode. If the forwarding mode is Greedy forwarding mode,

In step 606, the control block determines whether there is a hole by checking whether there is a neighboring node whose distance from the destination node is closer than that of the neighboring node itself. If there is no hole, the process moves to step 612. In step 612, the transmitting node forwards the packet to the next node through Greedy forwarding. If there is a hole, the flow moves to step 608 to set the node as a root node and set the transmission mode of the packet to the perimeter forwarding mode.

When the step 608 is completed, the root node includes its own location and address in the packet in step 610, and performs perimeter forwarding routing to the next node. The reason why the root node transmits its own location and address to the packet is to set a landmark to be described later.

If the method of forwarding the packet to its own node is the Perimeter Forwarding mode in step 604, the flow advances to step 614.

In step 614, the control block determines whether the Greedy forwarding scheme can be applied at the current location. That is, it is determined whether there is a neighboring node that is closer than the distance between the root node and the destination node among the neighboring nodes.

If there is a neighbor node that is closer than the distance between the root node and the destination node, go to step 616. In step 616, the transmitting node converts the transmission mode of the packet into the Greedy forwarding mode, and then performs Greedy forwarding.

When the step 616 is completed, the transmission node calculates the distance D (F, I) in step 618.

Referring to FIG. 7, a transmitting node 706 is a node located at the outside of the hole, and having a neighboring node that is closer than the distance between the root node 704 and the sink node 708. That is, the transmitting node 706 is a node capable of performing greedy forwarding.

The transmitting node 706 calculates the distance between the root node 704 that sensed the hole for the first time and the straight line connecting the sink node 708. [ If the distance calculation function is D (p1, line), the function D (p1, line) represents the vertical distance between the point p1 and the line. The distance from the point F to the straight line connecting the root node 704 and the sink node 708 is represented by a function D (F, I). When defining the position of the root node 704 and a sink node 708 as R (x _r, y _r), S (x _d, y _d), respectively, the distance D (F, I) is the following formula Can be calculated.

Upon completion of step 618, the control module determines whether the size of D is greater than or equal to a predetermined threshold value. If the size of D is less than or equal to the threshold value, it moves to step 626 to perform perimeter forwarding. In the case of small holes, the Perimeter forwarding scheme is more efficient than the Greedy forwarding scheme by the complex landmark setting scheme.

However, if the size of D is greater than or equal to the threshold value, the node moves to step 622 and generates a hole probe (Hp) packet. The hole probe packet includes a root field (Hp. ROOT), a left landmark field (Hp. L), and a right landmark field (Hp. R). The root field includes the location and address (ID) of the root node, the left landmark field includes its own node information, and the right landmark field contains information of the root node. When the node set as the root node forwards the packet in the perimeter forwarding mode, the node includes its location and address in the packet, so that the node can know the location and address of the root node.

When the step 622 is completed, the transmitting node performs perimeter forwarding of the hole probe packet to the nodes around the hole in step 624. The reason why the transmitting node transmits the hole probe packet by perimeter forwarding is to set an optimal landmark around the hole.

If there is no neighbor node that is closer than the distance between the root node 704 and the sink node 708 among the neighbor nodes in step 614, the transmission mode of the packet is maintained as the existing perimeter forwarding, Perform perimeter forwarding.

8 is a flowchart of a landmark setting method according to an embodiment of the present invention.

Referring to FIG. 8, in step 802, a node around a hole receives a hole probe packet in a Perimeter forwarding mode from a neighbor node.

In step 804, the landmark setting block compares the address of the root node of the received hole probe packet with its own address. If the node address of the node matches the address of the root node, the process proceeds to step 806. This means that when the home probe packet arrives at the root node, the hole probe packet returns to the root node via the neighboring nodes of the hole. In step 806, the root node receiving the home probe packet transmits the Hp packet in the Hp packet. L and Hp. And broadcasts the landmark position information of R to neighboring nodes.

If the node address of the node does not match the address of the root node, the process proceeds to step 808. In step 808, the landmark setting block sets the Hp. Make sure that the position of the left landmark of the L field and its current position are in the same direction with respect to the straight line connecting the root node and the sink node. To confirm this, the function S (F, L, l) described above is calculated. F, L, and l in the function S (F, L, l) represent the current node, the left landmark, and the straight line connecting the root node and the sink node, respectively.

When the step 808 is completed, it is checked in step 810 whether the function S (F, L, l) is greater than zero. If the result of the above function is larger than 0, it can be seen that it is in the same direction, and the direction is the left landmark direction. This is because the hole probe packet is transmitted by the right-hand rule of perimeter forwarding.

The distance D (L, l) between the node itself and the straight line l (the straight line connecting the root node and the sink node) to the left landmark and the straight line l in step 812 ).

If D (F, l) is greater than D (L, l), the process moves to step 814 and sets its current position to the position of the left landmark. This is to minimize the path that bypasses by selecting the landmark at the outermost edge of the hole. Then, in step 816, the home probe packet is transmitted through perimeter forwarding.

If D (F, l) is less than D (L, l) in step 812, Hp. Since the position of the left landmark of the L field is maintained, the process moves to step 816 and transmits the home probe packet through perimeter forwarding.

If the function S (F, L, l) is less than 0 in step 810, the flow advances to step 818. If the value of the function S (F, L, I) is less than 0, it can be confirmed that the left landmark and the current own position are in different directions, which indicates that the process is currently setting the right landmark .

The distance D (R, l) between the right landmark and the straight line 1 is compared with the distance D (F, l) between the node itself and the straight line l (the straight line connecting the root node and the sink node) in step 818.

If D (F, l) is greater than D (R, l), the process moves to step 820 and sets its current position to the right landmark position. In step 822, the home probe packet is transmitted through perimeter forwarding.

If D (F, l) is less than D (R, l) in step 818, Hp. Since the position of the landmark on the right side of the R field is maintained, the process moves to step 822 and transmits the home probe packet through the perimeter forwarding.

The optimum left landmark and the right landmark can be set through the above-described processes, and the hall can be bypassed using the set landmark.

FIG. 9 illustrates a routing path using landmarks according to an embodiment of the present invention.

9, the transmitting node 902 receives information about the landmark from the root node 904. [ The transmitting node 902 sets the temporary destination address of the packet to the address of the landmark and Greedy-Forwards the packet. The node 906 set as the landmark can effectively bypass the hole by greedy forwarding the packet received from the transmitting node to the destination node 908. [

The routing method according to the present invention sets a node located at the outermost node among the nodes around the hole as a landmark and transmits the packet from the transmission node to the destination node via the landmark. Routing using this landmark setting method can improve transmission efficiency by reducing routing overhead by at least 10% compared with conventional perimeter forwarding.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by equivalents to the appended claims, as well as the appended claims.

That is, in the detailed description of the present invention, an example for bypassing a hole in a greedy forwarding routing technique of a wireless sensor network is shown. However, the present invention can be applied to a similar technical background and a wireless network system without departing from the scope of the present invention, which can be done by a person skilled in the art.

FIG. 1 illustrates a perimeter forwarding scheme using a conventional right-hand rule; FIG.

2 is a configuration diagram of a sensor node according to an embodiment of the present invention;

3 illustrates a usable landmark region according to an embodiment of the present invention;

FIG. 4 illustrates locations of a transmission node and a landmark according to an embodiment of the present invention; FIG.

5 is a flow diagram of a routing technique according to an embodiment of the present invention;

6 is a flowchart of a hole sensing method according to an embodiment of the present invention;

FIG. 7 illustrates a root node and a transmitting node according to an embodiment of the present invention; FIG.

8 is a flowchart of a landmark setting method according to an embodiment of the present invention;

9 illustrates a routing path using landmarks according to an embodiment of the present invention.

Claims (15)

A routing method for bypassing a hole in a location based routing protocol, The sensor node receiving a data packet from a neighboring node and confirming a transmission mode of the received data packet; Comparing the distance between the neighboring node and the destination node to the distance between the root node and the destination node when the transmission mode is the Perimeter forwarding mode; Selecting a routing method for transmitting the data packet to a next node based on the compared distance; Calculating a size of the hole when there is a neighbor node that is closer than the distance from the destination node to the root node and comparing the size of the calculated hole with a predetermined threshold to determine a hole probe packet for setting a landmark A routing method for bypassing a hole including a generating process. The method according to claim 1, When usable landmark information received from neighboring nodes is detected, Wherein the sensor node further sets a temporary destination address to a location of the landmark and Greedy-forwarding the data packet to the set landmark location. The method according to claim 1, Wherein the size of the hole is the shortest distance between a straight line connecting the root node and the destination node and the sensor node. 2. The method of claim 1, wherein the step of selecting the routing method comprises: If the neighbor node is closer than the distance from the destination node to the root node, the data packet is perimeter forwarded,  And greedy forwarding the data packet if there is a neighbor node that is closer than the distance from the destination node to the root node. 5. The method of claim 4, And when the data packet is greedy forwarded to the next node, the transmission mode of the data packet is converted into Greedy forwarding mode. The method according to claim 1, When the size of the hole is larger than a predetermined threshold value, Further comprising the step of generating the hole probe packet and forwarding the perimeter to a node around the hole to set a landmark. The method according to claim 6, Wherein the hole probe packet includes a root field, a left landmark field, and a right landmark field. 8. The method of claim 7, Wherein the route field includes an address and a location of the root node, a location of the node itself in the left landmark field, and a location of the root node in the right landmark field. A landmark setting method for bypassing a hole in a location based routing protocol, The sensor node receiving a hole probe packet from a neighboring node; Confirming whether the address of the root node included in the received hole probe packet matches the node address of the node; When the address of the root node and the node address of the node do not coincide with each other, the left landmark position and the node position of the own probe packet are in the same direction with respect to the straight line connecting the root node and the destination node A process of determining whether or not to: Updating a position of a left landmark and a right landmark of the hole probe packet based on the determination; And And forwarding a hole probe packet including position information of the updated landmark to a next node. 10. The method of claim 9, If the address of the root node and the node address of the node match, And transmitting the information on the landmark in the hole probe packet to the surrounding nodes in order to notify the neighbor nodes of the information about the landmark in the hole probe packet. 10. The method of claim 9, Comparing the landmark position of the hole probe packet with the shortest distance between the straight line and the node position of the own probe and the shortest distance between the straight line; And updating the position of the landmark by comparing the shortest distances. 12. The method of claim 11, When the shortest distance between the node position and the straight line is greater than the shortest distance between the landmark position of the hole probe packet and the straight line, And updating the position of the landmark to its own node position. A sensor node using a location based routing protocol in a wireless sensor network, Checks the transmission mode of the data packet received from the neighboring node, If the verified transmission mode is a Perimeter forwarding mode, Comparing a distance between its own neighbor nodes and a destination node to a distance between the root node and the destination node and selecting a routing method for transmitting the data packet to the next node based on the compared distance, When a neighboring node that is closer than the distance from the destination node to the root node exists, calculates a size of the hole, compares the calculated size of the hole with a preset threshold value, and generates a hole probe packet for setting a landmark A sensor node comprising a control block for performing a control operation. 14. The method of claim 13, And a landmark setting block for setting a landmark for bypassing the hole with the shortest distance when the size of the hole is larger than a preset threshold value. 15. The method of claim 14, The landmark setting block checks whether the address of the root node included in the hole probe packet received from the neighboring node matches the node address of the node, When the address of the root node and the node address of the node do not coincide with each other, the left landmark position and the node position of the own probe packet are in the same direction with respect to the straight line connecting the root node and the destination node And, And updates the positions of the left landmark and the right landmark of the hole probe packet based on the determination.

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