KR101616278B1 - Grid Based Hybrid Routing System and Method in Mobile Ad-hoc Networks - Google Patents

Abstract

The present invention relates to a grid based hybrid routing system and method. The grid based hybrid routing system comprises: a path searching unit configured to enable each node to search a routing path in consideration of directivity with a destination node and information on neighboring nodes; a path selecting unit which is configured to calculate a minimum connection available time between nodes existing on the routing path and calculate the number of hops from a source node to the destination node while transmitting a route request (RREQ) message from the source node, and enables the destination node to select an optimum routing path through which data is to be transmitted in consideration of the minimum connection available time and the number of hops; and a path updating unit configured to enable a previous node of a node in which a problem occurs to re-search a routing path to the destination node when data is not transmitted through an initially-set routing path and thus transmission to the node fails. According to the present invention, transmission of messages for routing path generation may be reduced, management costs required for header selection, neighboring node management, path search and response procedures may be reduced, and costs required to generate alternative paths may be reduced.

Description

[0001] The present invention relates to a grid-based hybrid routing system and method in a mobile ad-hoc network,

The present invention relates to a mixed routing system and method, and more particularly, to a location based mixed routing system and method for creating and maintaining routing paths in consideration of connectivity in a grid-based environment.

As wireless communication and portable computing devices have evolved, the use of mobile devices has been rapidly increasing, and mobile ad hoc networks (MANETs) have been attracting much attention. MANET is easy to install and extend the network and enables wide range of communication through multi-hop communication. MANETs with these characteristics are widely applied in disaster areas and military environments. In addition, MANET consists of a set of autonomous mobile nodes that communicate with each other over a wireless link without a network infrastructure. That is, the mobile node itself forms a network between the mobile nodes without a repeater such as a base station or an access point (AP). MANET has the characteristics that the network topology changes dynamically due to unpredictable mobility and limited power and bandwidth. Because of this nature, the nodes are free and unpredictable, so the message transmission path to the destination is often broken, which reduces the overall performance of the network. Therefore, in MANET, various routing protocols with excellent stability that can effectively cope with network changes are actively researched. In addition, with the recent increase in the use of smartphones and tablet PCs, there is a continuing need for research into MANET environments that can provide faster and more reliable support for these devices.

MANET routing is divided into proactive, reactive, and hybrid protocols according to when and how the path is discovered using link information between nodes. In proactive routing, each node in the network manages routing path information for all destinations in the network. This proactive routing does not cause service delays because all nodes always maintain up-to-date routing information and results, but there is additional overhead cost for building and managing the latest routing tables. To address this overhead problem, on-demand reactive routing protocols have been introduced. Reactive routing broadcasts a Route Request (RREQ) message when the source node needs routing information in the process of transmitting the actual data. In this reactive routing, all the nodes do not manage the routing path, and it is advantageous in that the periodic traffic is reduced compared to the proactive method because it searches the route only when necessary and transmits the data. However, the reactive routing method generates a lot of control packets in the path search due to the topology change frequently occurred in the MANET, and performs the process of searching the routing path using the control message when data transmission or information sharing is required. Which leads to a high delay in obtaining information. Hybrid scheme is a mixture of proactive routing and reactive routing. Each node maintains routing information of neighboring nodes that are close to each other in advance and requests routing of distant nodes only when necessary. . The hybrid ZRP (Zone Routing Protocol) defines a specific area based on the number of hops of the route and manages only the routing information of nodes existing within a specific hop. In other words, the problem of the proactive method and the reactive method is solved by selectively applying the proactive method to the nodes in the area and the reactive method to the nodes outside the area. ZRP reduces the traffic overhead by reducing the number of flooding messages for route search by limiting periodic information exchange to local destination nodes located within a specific area. However, in ZRP, it is possible to apply the collective proactive method to all nodes within a specified hop, thereby storing information of a node in which actual communication rarely occurs, and information of a node frequently communicated may not be stored . Therefore, in such a zone-type routing, it is necessary to grasp a communication path in which data transmission occurs frequently, and to apply a proactive method to this path.

Unlike the conventional method of acquiring routing information with relative position information or link state between nodes, a method of routing using position information is also being studied. The location service is used by the sender of the packet to determine the location of the destination and to include the destination address of the packet. Location based routing uses the physical location information of the node for routing. A node can obtain its and its geographical location through GPS and location services. Availability of location information has a wide range of impacts at the network level as well as at the application level. The use of the physical location of the node can improve the efficiency of the mobile ad hoc network routing technology. Location-based routing has the advantage that it does not require or restricts routing path establishment and maintenance that takes up a lot of overhead. Location-based routing also has the advantage of being highly scalable.

There is a grid routing method that divides a physical area utilizing this location-based service into 2D grid areas. In MANET, most of the routing algorithms consist of the ID of the intermediate node and set the path. Failure to connect to a node on the path can lead to high routing overhead and data discontinuity in the process of communicating as the entire path is destroyed and the path reconnected or restored. However, the grid routing is performed through the path of the virtual grid connecting the target nodes. By dividing the fixed size grid network area, the path maintenance cost is reduced, and the probability of path loss is reduced to extend the service life. Each grid area has a head node that processes routing and is also referred to as a gateway node. The gateway node of each grid is selected to relay all packets passing through it. However, the throughput of the network can be limited to the fact that limited gateway nodes can transmit packets. Therefore, when the gateway node leaves the current grid area, much overhead is consumed to select a new gateway node. As the node speed increases, the overhead becomes very high.

As we have seen, existing studies require a lot of communication cost because they send messages to the entire network to create and maintain the routing path, and if data transmission is not possible through the established routing path, there is an additional cost to create a new path . In addition, the existing grid-based routing increases the management cost of the header because it keeps various information by putting a header in each area. In order to provide a mobile ad hoc network service, a routing technique that is adaptable to the change of the network topology according to node mobility and capable of reliably transmitting data from the source node to the destination node is needed.

Korean Patent Laid-Open Publication No. 10-2012-0046048 (Publication date 2012.05.09.) Korean Patent Publication No. 10-2010-0073947 (published on July 1, 2010)

SUMMARY OF THE INVENTION It is therefore an object of the present invention to reduce the cost of header management because headers are not provided and all nodes can transmit messages, Based on the positional relationship, the next hop to relay the message is determined. The routing path considering the direction of the node is exploited by using the coordinates of each grid area and the information of the neighboring node, and the routing path Based mixed routing system and method that maintains a plurality of grid-based routing systems.

According to another aspect of the present invention, there is provided a grid-based hybrid routing system comprising: a path search unit configured to search for a routing path by considering a direction of a destination node and information of neighboring nodes, Route request message from the source node to the destination node and calculates a minimum connectable time between nodes existing on the routing path and a hop count from the source node to the destination node, A route selection unit configured to select an optimal routing route to transmit data considering the number of hops, and a route selection unit configured to select, from the immediately preceding node of the node in question, Lt; RTI ID = 0.0 > route < / RTI > .

According to another aspect of the present invention, there is provided a grid-based hybrid routing method, comprising: a route search step in which a route search unit searches a routing path considering directionality of a destination node of each node and information of neighboring nodes; To calculate the minimum connectable time between nodes existing on the routing path and the number of hops from the source node to the destination node while transferring the minimum connectable time and the number of hops to the destination node, A path selection step of selecting an optimal routing path for transmitting data, and a path selecting step of selecting an optimal routing path for data transmission from the immediately preceding node to the destination node, And rediscovering the routing path.

As described above, according to the grid-based hybrid routing system and method of the present invention, message transmission for routing path generation is reduced by transmitting a message only to a partial area in the direction of a destination node by utilizing location information of a destination node, By creating a stable routing path considering the connectivity between the source and destination nodes and not having a header in each grid area, all the nodes can be candidates for delivering the message, and the header selection, neighbor node management, Procedures and the like, and if the message can not be transferred due to movement of the mobile node, it is possible to reduce the cost for generating the alternative path by generating an alternative path to the new destination node in the immediately preceding node of the node in question .

FIG. 1 is a block diagram schematically showing the overall configuration of a routing system according to a preferred embodiment of the present invention.
FIG. 2 is a diagram schematically illustrating an overall processing procedure of a routing method according to a preferred embodiment of the present invention.
3 is a flow chart illustrating the overall processing operation of a routing method according to a preferred embodiment of the present invention.
FIG. 4 is a diagram illustrating grid sizes generally used in the grid routing method according to the present invention.
5 is a diagram showing a relationship between the side length of the grid and the communication range.
6 shows a neighbor node of node 4. Fig.
FIG. 7 shows an INNT (intra neighbor node table) for node 4.
FIG. 8 shows a Neighbor Zone Node Table (NZNT) for the node 4. FIG.
FIG. 9 is a diagram illustrating a route search process taking a directionality into consideration according to a preferred embodiment of the present invention.
FIG. 10 is a diagram illustrating a route search process in which an RREQ message is transmitted from the source node 12 by taking the case of FIG. 9B as an example.
FIG. 11 shows an INNT (intra neighbor node table) for the node 12. FIG.
FIG. 12 shows a Neighbor Zone Node Table (NZNT) for the node 12. FIG.
13 is a diagram illustrating a path selection process according to a preferred embodiment of the present invention.
14 shows the path information stored in the RREQ message.
15 is a diagram illustrating a process of newly setting a routing path by partial path update according to a preferred embodiment of the present invention, that is, a path recovery process.

Hereinafter, a grid-based hybrid routing system and method according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram schematically showing the overall configuration of a routing system according to a preferred embodiment of the present invention.

FIG. 1 is a block diagram schematically showing the overall configuration of a routing system according to a preferred embodiment of the present invention.

Referring to FIG. 1, the grid-based mixed routing system of the present invention includes a path search unit 100, a path selection unit 200, and a path update unit 300.

First, the path search unit 100 sets the size of one grid area to be larger than the communication range of the node, keeps information about neighboring nodes existing within the communication range of each node, (INNT) that manages nodes in the area and a Neighbor Zone Node Table (NZNT) that manages 1 hop nodes existing in the same coordinate area. Each node manages the direction of the destination node and the neighbor node To search the routing path. Specifically, the route search unit 100 compares the coordinates of the grid zone (C_zone) where the current node is located with the coordinates of the grid zone (DN_zone) where the destination node is located, and outputs the RREQ message The proxy node searches the NZNT to determine whether there is a coordinate of a communicable neighbor zone. If there is a coordinate, the INNT is searched for and a neighboring zone And to transmit the message by searching for a node capable of transmitting.

Next, the path selector 200 calculates the connectable time and the number of hops by transmitting the RREQ (Route Request) message from the source node, and calculates the minimum connectable time between the nodes on the routing path And the number of hops from the source node to the destination node, and selects an optimal routing path for transmitting the data. At this time, the destination node selects the route with the minimum connectable time and the smallest hop count as the optimal routing route.

Lastly, the path update unit 300 is configured to redirect the routing path to the destination node from the immediately preceding node of the failed node when transmission to the node fails because the data can not be transmitted to the initially set routing path. In particular, the path update unit 300 of the present invention indicates that the next hop node according to the initially set routing path of the previous hop node having retransmitted the message does not need to transmit the message, and sends the other neighbor node to the next hop It is possible to prevent the occurrence of a so-called ping-pong effect in which a message repeats switching between specific nodes.

Hereinafter, the grid-based hybrid routing method of the present invention using the system configured as described above will be described.

FIG. 2 is a diagram schematically illustrating an overall processing procedure of a routing method according to a preferred embodiment of the present invention. According to a preferred embodiment of the present invention, the source node 3 transmits an RREQ (Route Request) message to the destination node 10 in order to generate a routing path, and the destination node transmits a RREP (Route Response) message in response thereto To the source node (3). Specifically, in a preferred embodiment of the present invention, each node transmits an RREQ message to three neighboring zones in the destination direction by comparing its current location coordinates with the coordinates of the destination node. That is, the source node 3 transmits the RREQ message to the three nodes 12, 4, and 37 in the destination direction, and the nodes receiving the message transmit the RREQ message until reaching the destination node 10 in the above- Message. The destination node 10 receiving the RREQ message selects an optimal routing path considering the connectivity and the number of hops among the routes included in the RREQ message and transmits the RREP message to the source node 3 through the generated route. The source node 3 receiving the RREP message transmits the actual data to the destination node through the optimal path included in the RREP message. Actual data is transmitted from the source node 3 to the destination node 10 via the nodes 4, 13, 28, 14, 21, 22, 1, 40, 25, 24,

A routing method according to a preferred embodiment of the present invention includes a routing path searching step, a path selecting step, and a path recovering step. A flowchart illustrating the overall processing operation of the routing method according to the preferred embodiment of the present invention is shown in FIG. At this time, it is assumed that the source node knows location information of its own and location information of the destination through a location recognition device such as GPS.

Referring to FIG. 3, all nodes of the present invention maintain information on neighboring nodes through periodic messages and nodes existing in the same coordinates, and manage them as a table. When a message is transmitted, The coordinates are compared (S110) and an area to which a message is to be transmitted is selected (S120). Then, a table containing information on neighboring nodes is searched (S130), and it is determined whether there is a node capable of being transmitted in the table (S140). If it is determined in step S140 that there is a node available for transmission in the table, each node transmits an RREQ message for generating a routing path based on the location information of its own neighbor nodes, the destination node, and the neighbor node information ). At this time, each node selects an optimal neighbor node as the next intermediate node, transfers data to the node, and gradually transfers the data to the destination node. In particular, according to a preferred embodiment of the present invention, path connectivity and the number of hops are calculated while transmitting an RREQ message, thereby enabling faster and more stable transmission. A more detailed process of the path search of the present invention will be described in detail with reference to FIGS. 9 to 12 on the assumption of FIGS. 4 to 8. FIG.

Next, the destination node having received the RREQ message locally selects an optimal route and transmits the RREP message to the source node (S210) so that the selected routes are gathered to form an effective routing in the entire network. This detailed route selection process of the present invention will be described in more detail in FIGS. 13 and 14. FIG.

If the transmission to the node fails during the message transmission according to the initially set routing path (S310), the path search is performed according to the path recovery algorithm (S320). The detailed procedure of the path recovery of the present invention will be described in more detail with reference to FIG.

FIG. 4A is a diagram showing a grid size generally used in a grid routing method such as the present invention. FIG. 4A shows a case where a head node of a grid cell communicates with nodes in four cells in the periphery other than diagonally adjacent cells, Figure 4b communicates with nodes of eight neighboring cells around a cell head node, and Figure 4c communicates with nodes of any eight neighboring cells. 5 is a diagram showing a relationship between the side length of the grid and the communication range. Where d is the length of the grid and r is the communication range.

One of the variables affecting the performance of a grid-based routing protocol such as the present invention is the grid size. Messages must move from one area to another. Other grid sizes can result in large differences in performance parameters (number of messages, delivery rate, latency, etc.). In a preferred embodiment of the present invention, the routing cost can be reduced by setting the size of one grid area to be larger than the communication range of the node. Since the 1-hop information is all known, the communication range need not be larger than the grid size, and the number of zones to be managed due to the large grid size is small. And since it does not use hierarchical header, all nodes can be candidates to send messages and header management cost does not occur. Therefore, the node management cost can be reduced. In addition, since the RREQ message is not sent to all nodes capable of communicating during the route search, the message overhead is reduced.

FIG. 6 shows a neighbor node of the node 4, and FIGS. 7 and 8 show an INNT (intra neighbor node table) and an NZNT (neighbor zone node table) of the node 4, respectively.

As shown in FIGS. 7 and 8, each node according to the preferred embodiment of the present invention transmits information about neighbor nodes existing in its communication range through an INNT (intra neighbor node table) NZNT (Neighbor Zone Node Table) Maintains two tables. INNT manages the nodes existing in the grid area where the current node exists, and NZNT manages one hop nodes existing in the same coordinate area. Each table is stored in a structure of <Node_ID, X_Coordinate, Y_Coordinate, Node_Velocity>. In this case, Node_ID is a node identifier, X_Coordinate and Y_Coordinate are x-axis y-axis coordinates of the grid area, and Node_Velocity is a speed at which the node moves, expressed as a speed (Vx, Vy) moving in the x-axis and the y-axis. Through these messages, each node maintains an INNT that manages information in the grid area to which it belongs and an NZNT that manages information outside the domain.

FIG. 9 is a diagram illustrating a route search process taking a directionality into consideration according to a preferred embodiment of the present invention.

According to a preferred embodiment of the present invention, a path search process is first performed to establish and select an optimal path for quickly and stably transmitting actual data from a source node to a destination node. In the existing mobile ad hoc network environment, the RREQ message is transmitted to the destination node using the broadcast method, and the destination node receiving the RREQ message transmits the RREP message in response to the source node. However, this method can exponentially increase the number of messages to be transmitted and increase the routing cost. Also, when there is no node that can transmit a message in the course of transmitting the RREQ message, the message is bypassed or the message is transmitted to the redundant path. In order to solve such a problem, in a preferred embodiment of the present invention, direction and direction of a destination node and information of neighboring nodes are considered when searching for a route.

In the route search method according to the preferred embodiment of the present invention, the coordinates of the Czone (current zone) and the coordinates of the DN_zone (destination zone) are compared with each other to select a DV_zone (delivery zone) C_zone is the grid area where the current node is located, DN_zone is the grid area where the destination node is located, and DV_zone is the grid area where the node of the current C_zone should transmit the message. The node at the current position compares the coordinates of the C_zone and the coordinates of the DN_zone, selects an adjacent DV_zone in the direction of the destination node, and transmits the RREQ message. 9 shows three neighboring DV_zones around a C_zone. In this case, x _c is the x coordinate of the C_zone, x _d is the x coordinate of the DN_zone, y _c is the y coordinate of the C_zone, and y _d is the y coordinate of the DN_zone. The current node in the C_zone sends the message to all three neighboring DV_zones. That is, as shown in FIG. 9A, if the x-axis value of the C_zone is larger than the x-axis value of the DN_zone and the y-axis value of the C_zone is smaller than or equal to the y-axis value of the DN_zone, three regions on the upper left are selected as the DV_zone. If the x-axis value of the C_zone is smaller than or equal to the x-axis value of the DN_zone and the y-axis value of the C_zone is smaller than or equal to the y-axis value of the DN_zone as shown in FIG. 9B, the three upper right regions are selected as the DV_zone. Likewise, if the x-axis value of the C_zone is larger than the x-axis value of the DN_zone and the y-axis value of the C_zone is smaller than the y-axis value of the DN_zone in FIG. 9C, then the lower left three regions are selected as the DV_zone. 9D, if the x-axis value of the C_zone is smaller than or equal to the x-axis value of the DN_zone and the y-axis value of the C_zone is larger than the y-axis value of the DN_zone, the three regions at the lower right are selected as the DV_zone.

Then, when a node receiving the first message in the three A-zone, B-zone, and C-zone selected by the DV_zone, that is, a node directly receiving a message from another C_zone is referred to as a proxy node, The node retrieves the two tables it manages. First, NZNT is searched and it is confirmed whether or not coordinates of a communicable neighbor zone exist. If there is a coordinate, the next INNT is searched and a message is transmitted by searching for a node capable of transmitting to a neighbor zone. If there is no information on the node in the NZNT and transmission to the neighbor zone is impossible, no further message is transmitted.

FIG. 10 is a diagram illustrating a route search process in which an RREQ message is transmitted from the source node 12 by taking the case of FIG. 9B as an example. 11 and 12 illustrate the INNT and NZNT tables of the node 12. FIG.

10 to 12, a node indicated by black is a source node and a node indicated by gray is a proxy node. Each node shares neighbor node information in the current grid area through a periodic update message. Therefore, all nodes of the grid area (1, 1) to which the source node belongs can know neighbor node information in the same area and can grasp which node can connect with the node of another grid area.

13 is a diagram illustrating a path selection process according to a preferred embodiment of the present invention.

In the routing scheme, the RREQ message is transmitted from the source node to the destination node, and the destination node receiving the RREQ message receives the RREP message in response to the RREQ message. If there are a plurality of paths capable of data transmission in this process, the cost of determining the optimal routing path to transmit actual data increases. Therefore, in the routing method according to the preferred embodiment of the present invention, an optimal routing path for transmitting data is selected in consideration of the connectable time and the number of hops. The RREQ message is transmitted from the source node to the destination node, the destination node which receives the RREQ message determines the optimal routing path to transmit the data, and transmits this information to the source node along the selected path by including this information in the RREP message. By considering the connectable time, more stable routing can be achieved by communicating with nodes capable of connecting for a longer period of time, and the communication cost can be reduced and transmission of data can be performed more quickly by transmission through a path having a small hop count. The RREQ message is transmitted from the source node and the connectable time and the number of hops are calculated. The destination node receiving the RREQ message determines the optimal routing path to transmit data using the information included in the message, and transmits the RREP message to the source node by including the information in the RREP message. The source node receiving the RREP message generates an optimal routing path for transmitting data to the destination node using the information included in the received message.

The data transmission cost is determined by the number of hops from the source node to the destination node. If the time available for communication between nodes is short, there is an additional cost of generating an alternative path in the process of transmitting data. Accordingly, in the routing method according to the preferred embodiment of the present invention, the routing path to transmit the actual data is determined in consideration of both the path connectivity and the number of hops. The routing path is determined by Equation (1) and the route with the largest RSV (Route Selection Value) is selected. RSV is a value used for selecting a path and has a higher value as the connectable time is longer and the number of hops is smaller.

Path connectivity is defined as the minimum connectable time between nodes on a routing path. When the routing path Ri for transmitting data from the source node to the destination node is {Ni ₁ , Ni ₂ , Ni ₃ , ..., Ni _k }, the connectable time RCT (R _i ) . Equation (2) is calculated as a minimum value of the time CTI _{i that} can be communicated between neighboring nodes, which is a time that can be stably communicated between nodes existing on the routing path. In Equation (2), CTI _i is calculated as Equation (3) as the maximum connectable time between two neighboring nodes on the routing path. MAX (t) means the maximum connectable time between two nodes. In the preferred embodiment of the present invention, the RREQ message is transmitted while the RREQ message includes the current position and the velocity of the node transmitting the RREQ message. This computes the position of the point of time t for each node. time t to the position of said node Nij from the point _{Pt (Ni ij) MAX (t} ) is | Pt (N _ij) - Pt (N +1 _ij) | two nodes adjacent to the maximum time satisfying R ≤ N _ij And N _ij + 1. Also, Tout represents the current time, and Pt (N0 _ij ) - Pt (N _ij +1) denotes the distance between nodes N _ij and N _ij +1 at time t.

FIG. 13 is a diagram illustrating a route selection process according to a preferred embodiment of the present invention. The route information included in the RREQ message is shown in FIG.

Referring to FIG. 14, there are a total of four paths from a source node to a destination node, and each path represents a path name, a node ID, a hop count, and connectivity. At this time, the destination node computes the RSV of Equation (1) to select one optimum path to transmit data among the four paths. When RSV is calculated for each path shown in FIG. 14, R ₁ is 2.2, R ₂ is 1.8, R ₃ is 1.7, and R ₄ is 1.6, so that R ₁ having the largest value is selected as an optimal path. Then, the destination node transmits route information of R ₁ along the route of the selected route R ₁ to the source node by including it in the RREP message. The source node that received the RREP message passes the actual data to the destination node along this path.

15 is a diagram illustrating a process of newly setting a routing path by partial path update according to a preferred embodiment of the present invention, that is, a path recovery process.

Due to the mobility of nodes in the MANET environment, it is often the case that the Hello message can not be seen for a certain period of time or the neighboring node can not transmit data to the initialized routing path due to movement to another location or the like. Therefore, an alternative path to perform data transfer must be created. If an alternative path is created through the same procedure as that of generating the initial routing path in the course of data transmission, the path request and response message as well as the transmission delay must be additionally transmitted. In order to solve such a problem, a routing method according to a preferred embodiment of the present invention uses partial path update. In the conventional method, when the transmission fails, an error message is sent to the source node, and the source node receiving the message takes a lot of time and additional expense because it starts a route re-search to search for a possible route. However, in the routing method according to the preferred embodiment of the present invention, since the routing path to the new destination node is searched in the immediately preceding node of the node in question, it is faster than the conventional method. By allowing the message to be redirected back to the previous node, the message can be discarded. The technique that is applied to the search for such a road is called a back-off method. However, simple application of such a backoff method to the routing method may result in a ping-pong effect in which the message repeats back and forth between certain nodes. This makes it impossible to transmit to the final destination node even though the message is still being transmitted. In order to escape from this problem, in the route updating process of the routing method according to the preferred embodiment of the present invention, the previous hop node receiving the message retransmitted by the backoff method is not required to transmit the message to the next hop node by the basic routing method And search for another neighbor node as the next hop for that message.

Referring to FIG. 15, node 1 is no longer able to receive the message of node 1 at node 22, assuming that node 1 has had a problem and its routing path is no longer available. Therefore, neighbor node 1 is deleted from the table of node 22 immediately before node 1, and a new routing path is found. In this case, node 22 finds hop node 2 for the destination node using the newly updated neighbor table and delivers the message. Then, the message is transmitted from the node 2 to the destination node through the node 53. Therefore, by using the path recovery method proposed in the present invention, it is possible to find a path for autonomously transmitting a message using only the neighbor node information.

As can be seen, the grid-based routing system and method of the present invention proactively manages routing information for nodes in the same grid area using hybrid routing to minimize route discovery messages. And reduces the periodic update message compared to the conventional scheme by providing an optimal path through a communicatable node connected to a node of an adjacent grid area in a reactive manner only when necessary. Also, we do not use the hierarchy by setting the grid to be larger than the communication radius and not placing a header. The header manages all information in the grid area and is responsible for message transmission. However, if the header moves away from the current grid area and moves to another area, a new header is selected. Therefore, additional costs such as header management and new header selection are increased. Therefore, the grid-based routing system and method of the present invention can be a candidate for delivering a message because all nodes of each grid on the path have no head node. Each intermediate node determines the next hop based on the positional relationship and the grid configuration. The message can be delivered to the nearest neighbors to the geographically desired grid area through the routing table that each node has. As described above, the grid-based routing system and method according to the present invention have an advantage in that node information is maintained in a grid-based structure, and thus it is not greatly affected by a change in a specific node constituting the topology.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

100: Path search section
200: path selector
300:

Claims (13)

Each of the nodes searching for a routing path by taking into consideration the directionality of the node and the information of the neighboring node,
The method comprising: transmitting a RREQ (Route Request) message from a source node to calculate a minimum connectable time between nodes existing on the routing path and a hop count from the source node to the destination node; A path selection unit configured to select an optimal routing path for transmitting data in consideration of the connectable time and the number of hops,
And a route update unit configured to redetect a routing path to the destination node from a node immediately before the node in question when transmission to the node fails because the data can not be transmitted to the initially set routing path,
Wherein the path search unit comprises:
Each node maintains information on neighboring nodes existing within its communication range and manages the nodes existing in the grid area in which the current node exists by using the INNT (IntraNeighbor Node Table) NZNT (Neighbor Zone Node Table) that manages nodes,
Wherein the path search unit comprises:
Each node compares a coordinate of a grid area (C_zone) where the current node is located and a coordinate of a grid area (DN_zone) where the destination node is located, and determines a transmission area (DV_zone) to transmit the RREQ message adjacent to the destination node direction A proxy node searches the NZNT to determine whether or not the coordinates of a communicable neighbor zone exist, and if there is such a coordinate, searches the INNT to find a node capable of transmitting to the neighboring area, RREQ &lt; / RTI &gt; message.
The method according to claim 1,
Wherein the path search unit comprises:
A grid-based hybrid routing system in which the size of one grid area is set larger than the communication range of the node.
delete delete delete The method according to claim 1,
Wherein the path selecting unit comprises:
(1) to (3), the optimal routing path is selected as the path having the largest RSV (Route Selection Value).
(1)

only,

Is the connectable time as shown in Equation (2) below,

Is the number of hops.
(2)

only,

Is the maximum possible connection time between two neighboring nodes on the routing path as shown in Equation (3). Here, k is a natural number.
(3)

only,

The maximum allowable connection time between two nodes,

Is the current time.
The method according to claim 1,
Wherein the path update unit comprises:
Wherein the previous node having retransmitted the message indicates that the next node by the initialized routing path is not needed for the message transmission and retrieves the other neighbor node to the next node for the message.
A path search step configured to search for a routing path by considering a direction of a destination node of each node and information of neighboring nodes,
Wherein the path selection unit calculates a minimum connectable time between nodes existing on the routing path and a hop count from the source node to the destination node while transmitting a RREQ message from the source node, A route selection step of selecting an optimal routing route to transmit data in consideration of the possible time and the number of hops,
If the transmission fails to transfer data to the initially set routing path and the transmission to the node fails, the route update unit re-searches the routing path for the destination node from the immediately preceding node of the node in question,
The path search step may include:
Setting the size of one grid area to be larger than the communication range of the node;
Each node maintains information on neighboring nodes existing within its communication range and manages the nodes existing in the grid area in which the current node exists by using the INNT (IntraNeighbor Node Table) And configuring a Neighbor Zone Node Table (NZNT) to manage the nodes,
The path search step may include:
Each node compares a coordinate of a grid area (C_zone) where the current node is located and a coordinate of a grid area (DN_zone) where the destination node is located, and determines a transmission area (DV_zone) to transmit the RREQ message adjacent to the destination node direction Selecting,
A step in which a proxy node searches the NZNT to confirm whether or not there is a coordinate of a communicable neighbor zone,
And if the coordinates of the neighboring area exist, searching the INNT to find a node capable of transmitting to the neighboring area and transmitting the RREQ message.
delete delete delete The method of claim 8,
Wherein the path selection step comprises:
Wherein the path selection unit selects an optimal routing path with the largest route selection value (RSV) according to the following equations (1) to (3).
(1)

only,

Is the connectable time as shown in Equation (2) below,

Is the number of hops.
(2)

only,

Is the maximum possible connection time between two neighboring nodes on the routing path as shown in Equation (3). Here, k is a natural number.
(3)

only,

The maximum allowable connection time between two nodes,

Is the current time.
The method of claim 8,
The re-searching of the routing path may include:
Based routing method, wherein the previous node, to which the route update unit has retransmitted the message, indicates that the next node by the initialized routing path is not needed for the message transmission, and that another neighbor node is retrieved to the next node for the message. .

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