KR101510902B1 - Method for transmitting routing information in an wireless networks - Google Patents

Abstract

The present invention relates to a method for efficiently transmitting a routing table in a wireless network. The present invention minimizes the overhead of the system by preventing unnecessary redundant transmission of the routing information in the routing vector based on the distance vector. In addition, the present invention can transmit routing information including a routing table entry requiring retransmission using an ACK message or a NACK message.

A routing table, a signal sequence value, an ACK message, a NACK message, a distance vector

Description

METHOD FOR TRANSMITTING ROUTING INFORMATION IN AN INTERNET NETWORKS [0002]

The present invention relates to a method for transmitting routing information in a wireless network, and more particularly to a method for transmitting routing information between neighboring nodes.

A routing technique in a network generally means a technique of setting a route until data transmitted from a sender arrives at a receiver. For example, in a multi-hop network, a source node may transmit a packet to a destination node that is not directly connected to the destination node, Function. To do this, the router receives the traffic from one input port, finds the best-path to which the packet will be forwarded to the other port, and sends it to the destination. In order for a router to determine the best route, it needs to know information about the topology of the network, which is possible by exchanging routing information between routers according to a predetermined protocol.

Generally, in a wireless network system, routing information known by a node is transmitted in a broadcast manner because it must be known to all the nodes in the vicinity. In a wireless network, since one node and neighboring nodes share a transmission medium, it is possible for all nodes in the neighbor to simultaneously receive packets in one transmission. However, since wireless networks are more affected by noise and interference than wired networks and channel conditions change from time to time, packets transmitted in a broadcast manner are not always received by all nodes. Therefore, the routing in the wireless network is performed by transmitting the routing information including the same information repeatedly several times.

The conventional routing scheme is divided into a link state (LS) scheme and a distance vector scheme (DV) scheme, and various modifications based on the schemes exist. The LS method is a method that informs the entire network when the link state of the link changes between two nodes, so that all the nodes in the network know the state of all links, thereby determining the optimal route to an arbitrary destination node. Meanwhile, in the DV scheme, each node stores an optimal path cost to each destination node in the routing table, and the contents of the routing table are exchanged with each other, thereby transmitting the packet to the destination node in the optimal path This is a way to know to which neighbor node the packet should be forwarded. Here, a neighbor node refers to a node that can directly transmit and receive a packet without going through another node.

Each node in the DV scheme periodically receives a routing table from a neighboring node. In the routing table, the minimum cost for the node to transmit a packet to an arbitrary destination is recorded. The purpose of the routing protocol is to select a path that always takes the least cost when transmitting an arbitrary packet to an arbitrary destination node, so that each node sees the contents of the table transmitted by its neighbor nodes, To be delivered. In order to determine the minimum cost path, a cost for transmitting a packet to a neighbor node is added to the cost value written in the routing table of the neighbor node. The sum of the costs finally transfers the packet to the destination through the neighbor node This is the minimum cost to be spent. Thus, the least cost path to a particular destination is the path each node must choose to deliver the packet. At this time, the minimum cost is the cost recorded in the routing table of the corresponding node. Since the routing table is periodically broadcasted to neighboring nodes, when the contents of a table of one node are changed, the change affects the table of the neighboring node. This effect is transmitted sequentially across the network, so that even if the network topology changes, all nodes can finally find a new minimum cost path.

Basically, in the DV scheme, the contents of the entire table are periodically broadcast to neighboring nodes regardless of changes in the contents of the routing table. Therefore, even if an error occurs in the transmission of the routing message temporarily, the routing table having the same contents is retransmitted in the next cycle. Therefore, even if a problem due to the transmission error occurs, it is limited to a temporary problem. However, the above method can waste unnecessary communication bandwidth by redundantly transmitting unnecessary information. Furthermore, since the size of the routing table is proportional to the total number of nodes and the transmission period of the table is shortened in proportion to the change rate of the topology, if the number of nodes is large and the topology change is severe, Occurs.

Therefore, each node can reliably transmit the routing information to all the neighbor nodes while maintaining the routing table, and at the same time eliminating redundantly transmitted information, there is a desperate need for improving the performance of the routing protocol and reducing the signaling overhead Is required.

SUMMARY OF THE INVENTION The present invention provides a method for reliably transmitting routing information between nodes in order to improve the performance of a routing protocol.

The present invention also provides a routing information transmission method for minimizing signaling overhead by preventing retransmission of unnecessary routing information in a wireless network.

A method for transmitting routing information in a wireless network, the method comprising: periodically transmitting routing information to at least one neighboring node; receiving a message including a signal sequence value from the neighboring node; Updating the signal sequence value of the transmitting node using the signal sequence value, and retransmitting the routing information using the updated signal sequence value.

The present invention minimizes the overhead of the system by preventing unnecessary redundant transmission of routing information in a routing scheme based on a distance vector. In particular, we propose a routing method that can efficiently transmit data in a mobile ad hoc network using low bandwidth and frequent topology changes.

In addition, the present invention is applicable not only to routing but also to all cases where a plurality of nodes periodically exchange a table composed of a plurality of entries.

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 routing information transmission method that minimizes signaling overhead by preventing transmission of unnecessary routing information in a wireless network. Therefore, in the embodiment of the present invention described below, a method of efficiently transmitting and receiving a routing table between nodes will be described in detail.

The present invention comprises a plurality of nodes constituting a wireless network. Each node has a routing table to be referred to for routing decision, and periodically broadcasts all or a part of its routing table to neighboring nodes.

In addition, each node in the present invention has a neighbor node table for recording information on all its neighbor nodes.

Hereinafter, the structure of the routing table used in the preferred embodiment of the present invention will be described in detail.

FIG. 1A shows a conventionally used routing table.

Referring to FIG. 1A, a routing table is composed of a plurality of entries having the same type, and one entry is composed of a plurality of fields required by a routing protocol. In general, each entry in the routing table contains information about a destination node, which includes the destination address and the optimal path cost from that node to the destination node.

On the other hand, FIG. 1B shows a routing table according to a preferred embodiment of the present invention.

Referring to FIG. 1B, the routing table of the present invention has the same structure as that of the existing routing table, but there is a difference in that a signal sequence value is added to the entries constituting the routing table. The signal sequence value is a value indicating how recently the information of the entry has been updated. The signal sequence value of the entry firstly inserted into the routing table may have a predetermined initial value, and the initial value may be arbitrarily set by the user.

Apart from the signal sequence value of the corresponding entry described above, each node has two values: a last acknowledged signaling sequence number (hereinafter referred to as LAS) and a maximal signaling sequence number (MXS) Lt; / RTI >

At the initial setup, all entries in the routing table have the same initial signal sequence value. The MXS has the same value as the initial signal sequence value, and the LAS has a value one less than the initial signal sequence value. Each node uses the signal sequence values when it broadcasts a routing message to a neighboring node. That is, each node does not include all the routing entries in the routing message (or routing information, for convenience of explanation, the routing message and routing information will be used for the following description), and the routing table in which the signal sequence value satisfies a predetermined range ≪ / RTI > The predetermined range is a case where the signal sequence value of the entry satisfies the following equation.

LAS <signal sequential value of the corresponding entry ≤ MXS

If LAS = MXS at the node sending the routing message, it means that all neighbors to the transmitting node have correctly received up to the most recently updated entry. In this case, the transmitting node does not include a routing table entry in the routing message. However, in the initial setting, LAS + 1 = the signal sequential value of the corresponding entry = MXS, so that all the routing table entries are included in the routing message according to Equation (1). Also, the current LAS and MXS values are recorded and transmitted in all routing messages. All nodes periodically transmit routing messages and receive periodically transmitted routing messages.

According to a preferred embodiment of the present invention, in order for each node to function as a receiving node, a neighbor signaling sequence number (hereinafter referred to as NSS) sequentially received from each neighboring node for all neighboring nodes is stored in a neighbor node table Record. The sequentially received signal sequence value refers to a signal sequence value in which all signal sequence values are received without a missing number in the middle of the signal sequence value.

FIG. 2 illustrates an NSS update method for each node to operate as a receiving node according to a preferred embodiment of the present invention.

Referring to FIG. 2, an NSS updating method for a case where the NSS value for the transmitting node is greater than the LAS value of the received routing message, and the case is small, will be described.

First, if the NSS value for the sending node is greater than the LAS value of the received routing message, the sending node transmits a routing message including a routing entry that is greater than the LAS value and less than or equal to the MXS value to the receiving node. That is, since the LAS value of the routing message to be transmitted is 17 and the MXS value is 22, the transmitting node transmits a routing message including an entry having a signal sequence value of 18 to 22. The NSS value for the transmitting node is 19 until the receiving node receives the routing message. This means that the receiving node has received the routing message from the current transmitting node up to the entry corresponding to the signal sequence value 19. When a receiving node receives a routing message including an entry having a signal sequence value of 18 to 22 from the transmitting node, the NSS value for the transmitting node is updated to the MXS value of the receiving message. Therefore, the NSS value for the transmitting node of the receiving node is updated from 19 to 22.

Second, when the NSS value of the transmitting node is equal to the LAS value of the received routing message, the transmitting node transmits an entry having a signal sequence value of 18 to 22. In this case, the NSS value for the transmitting node of the receiving node is 17, the LAS value of the routing message transmitted from the transmitting node is 17, and the MXS value is 22. The receiving node updates the NSS value of the transmitting node from 17 to 22 because the receiving node has received the routing message having the consecutive ranking sequence value.

Third, when the NSS value of the transmitting node is smaller than the LAS value of the received routing message, the transmitting node transmits an entry having a signal sequence value corresponding to 18 to 22 to the receiving node. On the other hand, the receiving node has received the routing table entry having the signal sequence value of 15 until receiving the routing message including the entry because the NSS value is 15. Therefore, the receiving node has not received the entry having the signal sequence value corresponding to 16 and 17. Therefore, the receiving node does not update the NSS value until the signal sequence value corresponding to 16 and 17 is received.

As described above, when each node operates as a receiving node, the NSS value is updated to identify a routing message received from neighboring nodes to date. The updated NSS value is used to update the LAS value to be described later.

Hereinafter, a method of updating the LAS and the MXS for each node to transmit routing information according to a preferred embodiment of the present invention will be described in detail.

First, the method of updating the MXS is to increment each node by 1 when there is an entry added or updated until each node transmits a routing message and then transmits a next routing message. If there is no entry to be added or updated when the next routing message is transmitted, the MXS value is maintained. At this time, the entry to be added or updated has an incremented MXS value as a signal sequence value. After the MXS value is increased by one, even if an entry is added or updated within the same period, the MXS value does not increase further. Also, entries added or updated in the same period all have the same signal sequence value.

For example, MXS (n) = MXS (n + 1) = MXS (n) if there is no entry to be added or updated from cycle n + 1 to cycle n + m. . = MXS (n + m). If there is an entry added or updated in the cycle n + m + 1, the signal sequence value of the entry becomes MXS (n + m + 1) = MXS (n) + 1. In this case, if there are other entries added or updated in the cycle n + m + 1, then all such entries have the same value as MXS (n + m + 1).

The node that transmits the routing message constructs the routing message by referring to the LAS value as well as the MXS value. A routing table entry having a signal sequence value less than or equal to the LAS value determines that all neighbors have successfully received the most recent value. Therefore, the node that transmits the routing message broadcasts to the neighboring node the entry having the signal sequence value of the entry larger than the LAS value and smaller than or equal to the MXS value in the routing message.

The method of updating the LAS value includes a method using an acknowledgment (ACK) and a method using a negative acknowledge (NACK). Hereinafter, a method for transmitting routing information using the two methods will be described in detail.

First Embodiment

FIG. 3 illustrates a routing information transmission method using an ACK message according to a first embodiment of the present invention. Referring to FIG. 3, a transmitting node transmits routing information using an ACK message received from each neighboring node.

When each node operates as a receiving node, the receiving node updates the NSS value of the corresponding transmitting node using the above-described NSS updating method. The updated NSS value is recorded in the ACK message and transmitted to the corresponding transmitting node. This is to inform the receiving node that the routing message is normally received from the corresponding transmitting node. The receiving node may individually transmit an ACK message to each of the transmitting nodes, or may combine the ACK message and the routing message into one packet for each period. Each transmitting node records the NSS value recorded in the last received ACK message from each neighbor node to all neighbor nodes in the neighbor node table. Each transmitting node refers to the neighboring node table before transmitting the routing message every period and updates the NSS value of the NSS values received from each neighboring node to the LAS value of the routing message.

If all previously updated table entries, including the most recently updated table entry, are normally received by all neighbor nodes, all neighbor nodes send the NSS value for that sending node to the MXS value recorded in the incoming message, i. E. And updates it with the MXS value of the corresponding transmitting node. Thereafter, the updated NSS value is reported to the transmitting node in an ACK message, and the transmitting node records the NSS values recorded in each ACK message in the corresponding neighbor node entry of the neighbor node table. If all ACK messages are normally received by the transmitting node, the NSS value of all neighbor nodes recorded in the neighbor node table becomes equal to the MXS value of the transmitting node. At this time, as described above, the LAS has the same value as the MXS, and the routing message transmitted thereafter does not include the routing table information. That is, if all the neighboring nodes sequentially receive up to the latest updated routing table entry, and the ACK messages are normally received, no further routing information is transmitted until the next routing table update.

If some nodes have not received recently updated routing information, they will not be able to send an ACK message for a recently updated signal sequence value. Therefore, the NSS value for some nodes recorded in the neighbor node table of the transmitting node will have a value smaller than the MXS value of the transmitting node. For example, if the smallest value among the NSS values for some of the neighboring nodes is m, the transmitting node updates LAS = m when the next routing message is transmitted. Accordingly, the transmitting node transmits routing table entries belonging to a range where the signal sequence value of the entry is larger than the LAS value and smaller than or equal to the MXS value. Therefore, all routing information that some nodes did not receive is retransmitted.

In this case, although all the neighboring nodes receive the routing message and transmit the ACK message to the neighboring node, some ACK messages may not be received by the transmitting node due to the error. At this time, the node that transmitted the ACK message does not retransmit the ACK message for the same routing information received from the transmitting node. Therefore, the routing information retransmitted due to the disappearance of the ACK message continues to be retransmitted from the transmitting node. In order to solve this problem, when the initial routing message is transmitted after updating the routing table, the transmitting node explicitly requests an ACK message for a neighboring node that has not received an ACK message for the recently transmitted routing information. The neighbor node receiving the ACK message request retransmits the ACK message to the corresponding transmitting node.

A routing information transmission method using the above-described ACK message will be described with reference to FIG.

When a transmitting node transmits a routing message to all neighboring nodes in the previous period (N-1), the transmitting node receives an ACK message from each neighboring node in the period N. [ At this time, the transmitting node records the NSS value recorded in the ACK message received from each of the neighboring nodes in the neighbor node table. The NSS value 22 is recorded in the ACK message of the neighbor nodes 2, 3, and 4, the NSS value 20 is recorded in the ACK message of the neighbor node 5, and the NSS value 17 is recorded in the ACK message of the neighbor node 1. That is, the neighboring nodes 2, 3, and 4 receive all the routing information transmitted from the transmitting node, and the ACK message is also normally transmitted. On the other hand, the neighbor node 5 has received the routing table entry from the transmitting node to the signal sequence value 20, and the neighbor node 1 has received the routing entry from the transmitting node to the signal sequence value 17. The smallest NSS value among the NSS values received from the neighboring nodes in the current period is updated to the LAS value of the transmitting node. Therefore, the LAS value of the routing message to be transmitted in the current period is updated to 17. Since the MXS value of the routing message in period N is 22, the transmitting node transmits routing information including entries having signal sequence values of 18 to 22 to all neighboring nodes.

Also, in the current cycle, the transmitting node explicitly requests an ACK message to neighboring node 1 and neighboring node 5. This is because there is a possibility that the neighboring node 1 and the neighboring node 5 correctly receive the routing information transmitted from the transmitting node, and then the ACK message transmitted to the transmitting node is lost. The ACK request message transmitted by the transmitting node in the current cycle may be transmitted individually or may be transmitted as one packet together with a routing message to be transmitted every cycle.

At period N + 1, neighbor nodes 1 and 5, which received an ACK request message in the previous cycle, retransmit an ACK message to the transmitting node. At this time, the transmitting node records the NSS value recorded in the ACK message transmitted from the neighboring node in the neighbor node table. The NSS value 22 is recorded in the ACK message retransmitted from the neighbor node 1, and the NSS value 20 is recorded in the ACK message retransmitted from the neighbor node 5. That is, the neighbor node 5 has still received routing entries up to the signal sequence value 20. In the current cycle, the LAS value of the routing message is updated to 20, and since there is no new entry in the current cycle, the MXS value is 22. Accordingly, the transmitting node transmits routing information including an entry having a signal sequence value of 21 to 22 to all neighboring nodes. Also, in the current cycle, the transmitting node explicitly requests the neighbor node 5 for an ACK message.

In the period N + 2, the transmitting node receives the ACK message having the NSS value of 20 from the neighboring node 5, and receives the ACK message having the NSS value of 22 from the neighboring nodes 1, 2, 3, When a new entry is generated in the period, the transmitting node does not request an ACK message to the neighboring node 5 and transmits an entry corresponding to a signal sequence value of 21 to 23 to all neighboring nodes. After receiving the routing information transmitted from the transmitting node, the neighboring node records the NSS value of the transmitting node in the ACK message and transmits the ACK message.

6 schematically shows a flow chart for transmitting routing information according to a first embodiment of the present invention.

Referring to FIG. 6, in step 602, the transmitting node periodically broadcasts routing information to at least one neighboring node. After receiving the routing information from the transmitting node, the neighboring nodes update the NSS value. The updated NSS value is recorded in the ACK message and transmitted to the corresponding transmitting node. In step 604, the transmitting node receives the ACK message.

In step 606, the transmitting node determines whether an ACK message has been received from all the neighboring nodes. That is, it is confirmed whether the NSS value received from the neighboring node is the MXS value of the recently transmitted routing message. If an ACK message is not received from at least one neighbor node, the transmitting node updates the MXS value and the LAS value to include an entry constituting a routing message to be retransmitted in the next period. Thereafter, in step 610, the transmitting node transmits a routing message including an entry whose signal sequence value of the entry is larger than the LAS value and smaller than or equal to the MXS value. In step 610, the transmitting node requests an ACK message to a neighboring node that has not received the ACK message. The routing message and the ACK request message transmitted in each cycle may be composed of one packet and transmitted.

If an ACK message is received from all the neighboring nodes in step 606, the BS proceeds to step 612. In step 612, the transmitting node updates the MXS value and the LAS value to configure a routing message to be transmitted in the next cycle. Thereafter, in step 614, the transmitting node transmits a routing message including an entry whose signal sequence value of the corresponding entry is larger than the LAS value and smaller than or equal to the MXS value.

If the ACK message is normally received from all the neighboring nodes for the routing message transmitted by the transmitting node, the LAS value and the MXS value of the transmitting node are the same. Therefore, the routing message transmitted in the next cycle does not include the routing table entry. However, even if all the ACK messages are normally received, if a newly updated entry occurs in the routing table of the transmitting node, the newly updated entry is included in the routing message to be transmitted in the next period and transmitted to all neighboring nodes. This is because the occurrence of the new entry causes the MXS value to increase by one.

According to the routing information transmission method described above, if some nodes do not receive the routing information, an ACK message is not transmitted from the certain node within the period. Therefore, if one of the neighboring nodes does not receive the routing message, the transmitting node retransmits the routing information including the routing table entry that the some node did not receive. The signaling overhead can be reduced by preventing the same information from being redundantly transmitted while maintaining the same transmission reliability, unlike the conventional routing table transmission scheme.

Hereinafter, a method for transmitting the routing information using the NACK message will be described in detail.

Second Embodiment

FIG. 4 illustrates a method of transmitting routing information using a NACK message according to a second embodiment of the present invention.

Referring to FIG. 4, a transmitting node transmits routing information using a NACK message received from each neighboring node.

In the embodiment of the present invention, it is assumed that routing information transmitted from the transmitting node to the neighboring nodes is normally received. Therefore, if there is no explicit retransmission request from some neighboring node, it is not transmitted.

The node receiving the routing message reads the LAS value recorded in the routing message transmitted from the transmitting node. If the LAS value is less than or equal to the NSS value for the corresponding transmitting node, the receiving node does not respond to the transmitting node. This is because it is in a state of sequentially receiving up to the signal sequence value included in the currently transmitted routing message.

On the other hand, when the LAS value recorded in the routing message is larger than the NSS value for the corresponding transmitting node, the receiving node transmits a NACK message to the transmitting node. The NACK message records the NSS value for the corresponding transmitting node. Like the above-described ACK message, the NACK message can be transmitted as a separate message, or can be transmitted as one packet together with a routing message to be transmitted in each period.

The transmitting node broadcasts a routing message to neighboring nodes every cycle and initializes the NSS value of each neighbor node of the neighboring node table to its own MXS value. This is because, as described above, it is assumed that all the routing information once transmitted to the neighboring nodes is normally received. If an arbitrary neighbor node receives a routing message sequentially from the transmitting node to the signal sequential value included in the received message (i.e., the LAS of the routing message and the NSS for the transmitting node) The NSS value of the corresponding neighbor node recorded in the neighbor node table maintains the initial value MXS.

On the other hand, when a routing message is received from the transmitting node and the signal sequence value included in the message is not sequentially received (i.e., the LAS of the routing message is NSS for the transmitting node), the receiving node transmits the NSS Value is recorded in the NACK message and transmitted. When the transmitting node receives the NACK message, it records the NSS value recorded in the NACK message in the corresponding neighbor node NSS item of the neighbor node table. Therefore, the transmitting node refers to the neighboring node table immediately before the next routing message transmission, and updates the minimum NSS value among the NSS values of each neighboring node to the LAS value of the new transmitting node. The transmitting node constructs a routing message to be transmitted in the next cycle using the LAS value and the MXS value.

As described above, if all the NACK messages transmitted in the previous period are normally received, the routing table entries that are not received by one or more neighboring nodes until the previous period are all retransmitted. However, in the embodiment of the present invention, when a NACK message is lost during transmission, a separate NACK message request is not required.

The routing information transmission method using the NACK message will be described with reference to FIG.

When an updated entry (entry having a signal sequence value of 21, 22) occurs in the routing table in the period N, the transmitting node broadcasts routing information including the updated entry to all neighboring nodes. In the current cycle, the transmitting node changes the NSS value for each neighbor node in the neighbor node table to its MXS value. That is, the transmitting node changes the NSS value for the neighbor node to the signal sequence value 22.

In the period N + 1, since the neighbor node 1 does not normally receive the routing information, the NSS value for the corresponding node is recorded in the NACK message and is transmitted to the corresponding node. At this time, the transmitting node records the NSS value received from the neighboring node 1 in the neighbor node table. The smallest NSS value among the NSS values of each neighbor node is updated to the LAS value of the routing message to be transmitted from the transmitting node. That is, in the period N + 1, the LAS value of the routing message to be transmitted by the transmitting node is 17. Thus, the transmitting node retransmits the routing information including the entries of signal sequence values 18 to 22. [

At period N + 2, if a NACK message is not received from neighboring nodes and a newly updated entry occurs, the transmitting node broadcasts routing information including only newly updated entries to all neighboring nodes.

7 schematically shows a flow chart for transmitting routing information according to a second embodiment of the present invention.

Referring to FIG. 7, in step 702, the transmitting node periodically broadcasts routing information to at least one neighboring node. After receiving the routing information, the neighboring node determines whether the routing table entry has been sequentially received up to the signal sequence value included in the routing message. If the neighboring node sequentially receives the routing table entry (that is, the LAS of the routing message and the NSS of the transmitting node), the receiving node does not respond to the transmitting node. On the other hand, when the neighboring node does not sequentially receive the routing table entry (i.e., the LAS of the routing message> the NSS of the transmitting node), the NACK message is transmitted to the corresponding transmitting node. In the NACK message, the NSS value of the transmitting node of the corresponding neighbor node is recorded.

In step 704, the transmitting node receives a NACK message from a neighboring node requiring retransmission. The transmitting node records the NSS value recorded in the NACK message in the corresponding neighbor node NSS item of the neighbor node table. In step 706, the transmitting node updates the MXS value and the LAS value of the routing message to be transmitted in the next cycle. That is, the transmitting node refers to the neighbor node table immediately before transmission of the next routing message, and updates the minimum NSS value among the NSS values of each neighbor node to a new LAS value.

In step 708, the transmitting node retransmits the routing information using the MXS and LAS values. Also, if a newly updated entry is generated in the routing table of the transmitting node, the newly updated entry is included in the routing message to be transmitted in the next period and is transmitted to all the neighboring nodes.

In the routing information transmission method described above, a NACK message is transmitted only when unnecessary retransmission does not occur and retransmission is required. Also, since the transmitting node does not need to request an explicit NACK message, the signaling overhead is reduced as compared with the routing information transmission method using the ACK message. However, when the transmission of the NACK message fails, the retransmission of the necessary routing information may not occur. Therefore, the reliability of the transmission method using the ACK message is lower than that of the transmission method using the ACK message.

Third Embodiment

FIG. 5 illustrates a method of transmitting routing information using a NACK message according to a third embodiment of the present invention.

Referring to FIG. 5, a transmitting node transmits routing information including only an entry requiring retransmission, using a NACK message received from each neighboring node.

Each receiving node stores signal sequence values that it has not received from the corresponding transmitting node for each transmitting node each time a routing message is received, and then records the signal sequence value in a NACK message and transmits the signal sequence value. At this time, the transmitting node combines the list of the signal sequence values recorded in the NACK message transmitted by each receiving node, and includes the entries having the signal sequence value included in the NACK message at least once in the routing message in the next cycle.

The routing information transmission method using the NACK message will be described with reference to FIG.

When an updated entry (an entry having a signal sequence value of 21 or 22) occurs in the routing table in the period N, the transmitting node broadcasts the routing information including the updated entry to all the over nodes.

In the period N + 1, the neighbor nodes 1 and 5 record the signal sequence values not received from the corresponding transmitting node in the NACK message and transmit the same. The transmitting node merges the entries corresponding to the signal sequence values not received by the neighboring nodes 1 and 5. Therefore, the transmitting node includes an entry corresponding to the signal sequence values 16, 17, and 18 in the routing message transmitted in the current period.

If the NACK message is not received from the neighbor nodes in the period N + 2 and a newly updated entry occurs, the transmitting node broadcasts the routing information including only the newly updated entry to all the neighbor nodes.

8 schematically shows a flow chart for transmitting routing information according to a third embodiment of the present invention.

Referring to FIG. 8, in step 802, the transmitting node periodically broadcasts routing information to at least one neighboring node. Each receiving node stores signal sequence values that it has not received from the corresponding transmitting node for each transmitting node each time a routing message is received, and then records the signal sequence value in a NACK message and transmits the signal sequence value.

In step 806, the transmitting node integrates the signal sequence value list recorded in the NACK message. In step 807, the transmitting node retransmits the routing message including only the entry corresponding to the integrated signal sequence value.

The routing information transmission method described above improves the routing information transmission method according to the second embodiment of the present invention, so that only the entries requiring retransmission can be selected and retransmitted, thereby further reducing the signaling overhead.

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, the detailed description of the above-mentioned invention shows an embodiment for improving the routing information transmission method based on the distance vector method in the wireless network. However, the present invention can be applied to a method of exchanging a table between neighboring nodes, even if the method is different from the distance vector method, but the present invention can be applied in a range not greatly departing from the scope of the present invention. It will be possible at the judgment of the person having technical knowledge.

Figure 1A shows a routing table used in the prior art;

FIG. 1B shows a routing table according to a preferred embodiment of the present invention; FIG.

Figure 2 illustrates a method of updating an NSS at a receiving node according to a preferred embodiment of the present invention;

FIG. 3 illustrates a method of transmitting routing information using an ACK message according to a first embodiment of the present invention; FIG.

4 is a diagram illustrating a method of transmitting routing information using a NACK message according to a second embodiment of the present invention;

FIG. 5 illustrates a method of transmitting routing information using a NACK message according to a third embodiment of the present invention; FIG.

6 is a flow diagram for transmitting routing information according to a first embodiment of the present invention;

7 is a flow diagram for transmitting routing information according to a second embodiment of the present invention;

8 is a flow chart for transmitting routing information according to a third embodiment of the present invention;

Claims (7)

A method for transmitting routing information at a node constituting a wireless network, Periodically transmitting routing information to at least one neighboring node; Receiving a message including a signal sequence value indicating how recently information on a destination node of the entry has been updated from the at least one neighbor node; Updating its own signal sequence value using a signal sequence value in the received message; And And retransmitting the routing information using the updated signal sequence value. The method according to claim 1, And the message is an ACK message. 3. The method of claim 2, And requesting the ACK message if an ACK message is not received from the at least one neighboring node. The method according to claim 1, Wherein the message is a NACK message. 5. The method of claim 4, Wherein the retransmitting step incorporates a signal sequence value recorded in the NACK message and retransmits only a routing table entry corresponding to the combined signal sequence value. The method according to claim 1, Wherein the updated signal sequence value is a last acknowledged signaling sequence number and a maximal signal sequence number. The method according to claim 6, Wherein the retransmitting comprises retransmitting routing information including only a routing table entry whose signal sequence value of the entry is greater than the recently received signal sequence value and less than or equal to the maximum signal sequence value.

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