KR101136051B1 - Multicast routing method in wireless mobile multi-hop network system - Google Patents

Abstract

The present invention relates to a multicast routing method in a wireless mobile multihop network system. Multicast routing method in a network system according to an embodiment of the present invention comprises the steps of establishing a data transmission path between the source node and the target node through the transmission and reception of control packets; Transmitting data packets from the source node to the destination node through at least one forwarding node constituting the data transmission path; Recovering the disconnected data transmission path if the data transmission path is disconnected; If at least one data packet is lost during the time period during which the data transmission path was disconnected, a recovery request packet including the sequence number of the lost at least one data packet is received at the destination node of the at least one forwarding node. Transmitting to a forwarding node one-hop neighboring with the node; And in response to the restoration request packet, transmitting at least one data packet corresponding to the sequence number from a forwarding node one-hop neighboring with the target node to the target node. According to the multicast routing method according to an embodiment of the present invention, the reception rate (reliability) of a data packet can be increased while reducing the overhead due to transmission and reception of control packets in a wireless mobile multihop network system.

Description

Multicast routing method in wireless mobile multi-hop network system {MULTICAST ROUTING METHOD IN WIRELESS MOBILE MULTI-HOP NETWORK SYSTEM}

The present invention relates to a multicast routing method, and more particularly to a multicast routing method in a wireless mobile multi-hop network system.

In a wireless mobile multi-hop or mobile ad-hoc network (hereinafter referred to as MANET), nodes can communicate with each other without a wired infrastructure or a central control unit. Therefore, MANET is useful in environments where wired infrastructure is not built or difficult to access.

According to the On-Demand Multicast Routing Protocol (ODMRP) used in MANET, the multicast data transmission path allows the transmission and reception of control packets between nodes in a multicast group. Is set through. However, the path set in this way may be broken due to the mobility of nodes. Therefore, transmission and reception of control packets should be performed periodically to maintain the path.

However, in a network based on ODMRP, the transmission and reception of these periodic control packets incurs a lot of overhead throughout the network. Here, the time interval in which control packets occur is one of the factors affecting overhead and reliability. If the time interval over which control packets occur is too short, limited resources at a given channel bandwidth are wasted due to increased overhead. On the other hand, if the time interval over which control packets occur is too long, reliability is lost due to data packet loss caused by path disconnection. This means that the data packet reception rate is reduced.

It is an object of the present invention to provide a multicast routing method for recovering lost data packets during path recovery or reconfiguration in a wireless mobile multi-hop network system.

Multicast routing method in a wireless mobile multi-hop network system according to an embodiment of the present invention comprises the steps of establishing a data transmission path between the source node and the destination node through the transmission and reception of control packets; Transmitting data packets from the source node to the destination node through at least one forwarding node constituting the data transmission path; Recovering the disconnected data transmission path if the data transmission path is disconnected; If at least one data packet is lost during the time period during which the data transmission path was disconnected, a recovery request packet including the sequence number of the lost at least one data packet is received at the destination node of the at least one forwarding node. Transmitting to a forwarding node one-hop neighboring with the node; And in response to the restoration request packet, transmitting at least one data packet corresponding to the sequence number from a forwarding node one-hop neighboring with the target node to the target node.

In an embodiment, in transmitting the data packets from the source node to the destination node, the data packets are stored in a packet queue of the at least one forwarding node.

The setting of the data transmission path may include: periodically generating a subscription query packet among the control packets; And flooding the subscription query packet to all nodes belonging to a multicast group.

The multicast routing method according to the embodiment, in the step of periodically generating the subscription query packet, the generation period of the subscription query packet is variable according to the reception rate of the data packet.

In an embodiment, in the step of periodically generating the subscription query packet, the generation period of the subscription query packet decreases as the reception rate of the data packet increases, and increases as the reception rate of the data packet decreases.

In an embodiment, the restoring of the data transmission path may include performing a local path recovery.

The transmitting of the data packets from the source node to the destination node may include determining whether the data packets are normally transmitted through a passive acknowledgment response.

In a wireless mobile multi-hop network system according to an embodiment of the present invention, the multicast routing method includes at least one forwarding node that relays the data packets while data packets are transmitted through a data transmission path between a source node and a destination node. Storing the data packets in a packet queue; If at least one data packet is lost while the data packets are being transmitted, the destination node of the at least one forwarding node at the destination node issuing a recovery request packet containing the sequence number of the at least one lost data packet. Transmitting to a 1-hop neighboring forwarding node; And forwarding one-hop neighboring the destination node with at least one data packet corresponding to the sequence number among the data packets stored in the packet queue of the forwarding node that is one-hop neighboring with the destination node. Transmitting from the node to the destination node.

In an embodiment, the multicast routing method may further include restoring the disconnected data transmission path when the data transmission path is disconnected.

In an embodiment, the repairing of the disconnected data transmission path may include performing a local path recovery.

The recovering of the disconnected data transmission path may include resetting the data transmission path through transmission and reception of periodic control packets.

In an embodiment, the resetting period of the data transmission path may vary depending on a reception rate of the data packet.

According to the multicast routing method according to an embodiment of the present invention, the reception rate (reliability) of a data packet can be increased while reducing overhead due to transmission and reception of control packets in an On-Demand Multicast Routing Protocol (ODMPRP) -based network system. .

1 is a diagram for exemplarily describing a multicast routing method in an ODMRP-based network system.
2A through 2C are diagrams for describing a multicast routing method using local path recovery according to an embodiment of the present invention.
3 is a flowchart illustrating a multicast routing method of adjusting a rerouting period according to a reception rate of a data packet.
4 is a diagram illustrating a multicast routing method using a passive ACK.
5 is a flowchart illustrating a multicast routing method for recovering lost data packets by retransmitting data packets stored in a packet queue.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the technical idea of the present invention.

The multicast routing method according to an embodiment of the present invention is applied to a mobile ad-hoc network (hereinafter referred to as MANET). The network system according to an embodiment of the present invention is based on an on-demand multicast routing protocol (hereinafter, referred to as ODMRP).

1 is a diagram for exemplarily describing a multicast routing method in an ODMRP-based network system. Referring to FIG. 1, a multicast group of a MANET according to an embodiment of the present invention is illustrated by way of example. The multicast group includes a source node S, a destination node D, and first to sixth forwarding nodes F1 to F6.

For simplicity, it is assumed that a multicast group according to an embodiment of the present invention includes one source node S and one destination node D. However, as an example, a multicast group may include a plurality of source nodes and a plurality of destination nodes.

In order to establish a path for data packet transmission between the source node S and the destination node D, a process of configuring a mesh by selecting forwarding nodes through periodic transmission and reception of control packets is required. Here, the set of forwarding nodes elected to mediate the data packet between the source node S and the destination node D is called a forwarding group.

The data packet transmission path between the source node S and the destination node D is established through an inquiry step and a response step. First, the querying step is described. The source node S floods a control packet (hereinafter referred to as a subscription query packet) including a join query message and identification information. In this case, flooding means transmitting a packet to all neighboring nodes. The source node S and the first forwarding node F1, which is a one-hop neighbor node, receive the broadcast subscription packet from the source node S. The first forwarding node F1 stores the identification information of the source node S in the routing table and adds its identification information to the subscription query packet. The first forwarding node F1 then broadcasts the subscription query packet.

The second to fourth nodes F2 to F4 receive the subscription query packet broadcast from the first forwarding node F1. Each of the second to fourth forwarding nodes F2 to F4 stores the identification information of the source node S and the first forwarding node F1 in the routing table, and adds its identification information to the subscription query packet. . Thereafter, each of the second to fourth forwarding nodes F2 to F4 broadcasts a subscription query packet. In this way the subscription query packet is broadcast to all other nodes in the multicast group.

Next, the response step is described. After receiving the subscription query packet, the destination node D transmits a control packet (hereinafter, referred to as a subscription reply packet) including a join reply message to the source node S in response thereto. At this time, the first and second forwarding nodes F1 and F2 mediate the subscription response message with reference to the identification information stored in the respective routing tables. The first and second forwarding nodes F1 and F2 which mediate the subscription query packet and the subscription response packet between the source node S and the destination node D are elected as members of the forwarding group.

As such, when the data packet transmission path is established through the inquiry step and the response step, the source node S transmits the data packets to the destination node D. At this time, the first and second forwarding nodes F1 and F2 mediate data packets between the source node S and the destination node D. FIG.

However, the data packet transmission path may be broken due to the mobility of the nodes. Therefore, transmission and reception of control packets should be performed periodically to maintain the path. That is, periodic rerouting is necessary. In this case, the rerouting period affects the reception rate of the data packet and the overhead due to transmission and reception of control packets. As the rerouting period gets shorter, the overhead increases but the loss of data packets decreases. On the other hand, as the rerouting period is longer, the loss of data packets increases, but the overhead decreases.

The network system according to an embodiment of the present invention is enhanced to support a local path recovery function, a function of adjusting a path reset period according to a data packet reception rate, a passive acknowledgment (hereinafter, referred to as a passive ACK), and the like. It can be based on ODMRP (Enhanced-ODMRP, hereinafter referred to as E-ODMRP). The multicast routing method by local path recovery is described below with reference to FIGS. 2A to 2C. A multicast routing method for adjusting the rerouting period according to the reception rate of the data packet is described with reference to FIG. 3 below. A multicast routing method using a passive ACK is described with reference to FIG. 4 below.

2A through 2C are diagrams for describing a multicast routing method using local path recovery according to an embodiment of the present invention. For the sake of brevity, it is assumed that the destination node D leaves and rejoins the multicast group shown in FIG. In the following, the matters already described with reference to FIG. 1 are omitted.

Referring to FIG. 2A, the destination node D floods a control packet (hereinafter referred to as a join request packet) including a join request message to rejoin the multicast group. The destination node D and the second and fifth forwarding nodes F2 and F5, which are one-hop neighbor nodes, receive the broadcast subscription request packet from the destination node D.

Referring to FIG. 2B, the second and fifth forwarding nodes F2 and F5 that have received the broadcasted subscription request packet operate as temporary forwarding nodes. That is, the second and fifth forwarding nodes F2 and F5 intermediate data packets temporarily until one of the second and fifth forwarding nodes F2 and F5 is selected as a member of the forwarding group.

The destination node D selects a temporary forwarding node constituting the shortest path as a member of the forwarding group. To this end, a control packet (hereinafter, referred to as a path selection packet) including a path selection message and identification information of a temporary forwarding node constituting the shortest path is broadcasted. Here, the temporary forwarding node constituting the shortest path is the second forwarding node F2. That is, the identification information included in the path selection packet indicates the second forwarding node F2. The second and fifth forwarding nodes F2 and F5 receive the broadcast path selection packet from the destination node D.

Referring to FIG. 2C, the second and fifth forwarding nodes F2 and F5 confirm identification information included in the path selection packet. Since the identification information included in the path selection packet indicates the second forwarding node F2, the second forwarding node F2 is selected as a member of the forwarding group and continues to relay data packets. On the other hand, the fifth forwarding node F5 no longer transmits data packets to the destination node D.

As described above, according to the multicast routing method using the local path recovery, control packets are transmitted and received between the destination node D and the 1-hop neighbor node. Thus, for rerouting, overhead can be reduced compared to the transmission and reception of control packets between the source node S and all other nodes in the multicast group.

3 is a flowchart illustrating a multicast routing method of adjusting a rerouting period according to a reception rate of a data packet. Here, the rerouting period means a time interval in which the control packet (subscription query packet) is flooded from the source node (S).

Referring to FIG. 3, in a network system according to an exemplary embodiment of the present disclosure, a reception rate of a data packet is monitored (step S110). At this time, the reception rate of the high data packet means that the mobility of the nodes is low, so that the data packet loss is low. In this case, it is desirable to increase the rerouting period to reduce the overhead. On the other hand, the low data packet reception rate means that the mobility of nodes is high, resulting in high data packet loss. In this case, it is desirable to reduce the rerouting period to increase the reliability.

Then, the reception rate of the data packet is compared with the reference value (step S120). If the reception rate of the data packet is equal to the reference value, then the reception rate of the data packet is continuously monitored. On the other hand, if the reception rate of the data packet is different from the reference value, the rerouting period is adjusted (step S130). That is, the time interval at which the subscription query packet is flooded from the source node S is adjusted. For example, if the reception rate of the data packet is greater than the reference value, the rerouting period is increased to reduce overhead. On the other hand, if the reception rate of the data packet is smaller than the reference value, the rerouting period is reduced to increase the reliability.

As described above, according to the multicast routing method of adjusting the rerouting period according to the reception rate of the data packet, the rerouting period is maintained at an appropriate level to reduce the overhead due to transmission and reception of control packets.

4 is a diagram illustrating a multicast routing method using a passive ACK. Referring to FIG. 4, the source node S transmits a data packet to the first forwarding node F1, which is a one-hop neighbor node. The first forwarding node F1 broadcasts the data packet transmitted from the source node S. The source node S may receive the broadcast data packet from the first forwarding node F1. At this time, the data packet transmitted from the first forwarding node F1, which is a lower node, to the source node S, which is an upper node, is treated as a passive ACK.

Since each node belonging to the multicast group stores the identification information of the upper node and the lower node in the routing table, when the source node S receives the passive ACK, whether the data packet is normally transmitted by referring to the routing table. You can check. Therefore, even if the first forwarding node F1 does not transmit a separate ACK to the source node S after receiving the data packet from the source node S, the source node S normally receives the data packet through the passive ACK. You can check whether it was sent.

If the source node S does not receive the passive ACK several times from the first forwarding node F1, the source node S determines that the first forwarding node F1 does not belong to the forwarding group and removes the data packet. 1 does not transmit to the forwarding node F1. The same applies to the relationship with the first and second forwarding nodes F1 and F2.

As described above, according to the multicast routing method using the passive ACK, it is possible to reduce the overhead due to the data packet is transmitted to the unnecessary forwarding node.

An embodiment of the present invention provides a multicast routing method for recovering lost data packets by retransmitting data packets stored in a packet queue in an E-ODMRP-based network system. This is explained with reference to FIG. 5 below.

5 is a flowchart illustrating a multicast routing method for recovering lost data packets by retransmitting data packets stored in a packet queue. For the sake of brevity, it is assumed that the destination node leaves the multicast group shown in FIG. 1 and then rejoins it.

Referring to FIG. 5, the destination node rejoins the multicast group by local path recovery or rerouting through transmission and reception of a subscription query packet and a subscription response packet (step S210). Thereafter, the destination node checks whether there are any lost data packets while the path is restored or reset (step S220).

Each node belonging to the multicast group stores data packets to be transmitted or brokered in a packet queue. Thus, even if a loss of the data packet occurs between the forwarding node and the destination node, the destination node may request the forwarding node to retransmit the lost data packet. To this end, if there is a lost data packet, the destination node sends a control packet (hereinafter referred to as a recovery request packet) including a recovery request message and a sequence number of the lost data packet to the forwarding node ( Step S230).

The forwarding node receiving the restoration request packet transmits a data packet corresponding to the sequence number included in the restoration request packet among the data packets stored in the packet queue to the target node (step S240).

As described above, according to the multicast routing method of restoring lost data packets by retransmitting the data packets stored in the packet queue, reliability due to an increase in the reception rate of the data packets can be improved.

It will be apparent to those skilled in the art that the structure of the present invention can be variously modified or changed without departing from the scope or spirit of the present invention. In view of the foregoing, it is intended that the present invention cover the modifications and variations of this invention provided they fall within the scope of the following claims and equivalents.

Claims (12)

In a multicast routing method in a wireless mobile multihop network system:
Establishing a data transmission path between a source node and a destination node through transmission and reception of control packets;
Transmitting data packets from the source node to the destination node through at least one forwarding node constituting the data transmission path;
When the data transmission path is disconnected, performing local path recovery to recover the disconnected data transmission path;
If at least one data packet is lost during the time period during which the data transmission path was disconnected, a recovery request packet including the sequence number of the lost at least one data packet is received at the destination node of the at least one forwarding node. Transmitting to a forwarding node one-hop neighboring with the node; And
In response to the reconstruction request packet, transmitting at least one data packet corresponding to the sequence number from a forwarding node one-hop neighboring the destination node to the destination node. The method of claim 1,
Transmitting the data packets from the source node to the destination node, wherein the data packets are stored in a packet queue of the at least one forwarding node. The method of claim 1,
The setting of the data transmission path may include: periodically generating a subscription query packet among the control packets; And
Flooding the subscription query packet to all nodes belonging to a multicast group. The method of claim 3, wherein
In the step of periodically generating the subscription query packet, the generation period of the subscription query packet is variable according to the reception rate of the data packet. The method of claim 4, wherein
In the step of generating the subscription query packet periodically, the generation period of the subscription query packet decreases as the reception rate of the data packet increases, and increases as the reception rate of the data packet decreases. delete The method of claim 1,
The transmitting of the data packets from the source node to the destination node includes determining whether the data packets are normally transmitted through a passive acknowledgment response. In a multicast routing method in a wireless mobile multihop network system:
Storing the data packets in a packet queue of at least one forwarding node that mediates the data packets while data packets are being transmitted over a data transmission path between a source node and a destination node;
When the data transmission path is disconnected, performing local path recovery to recover the disconnected data transmission path;
If at least one data packet is lost while the data packets are being transmitted, the destination node of the at least one forwarding node at the destination node issuing a recovery request packet containing the sequence number of the at least one lost data packet. Transmitting to a 1-hop neighboring forwarding node; And
A forwarding node one-hop neighboring the destination node with at least one data packet corresponding to the sequence number among the data packets stored in the packet queue of the forwarding node that is neighboring the destination node one-hop; Transmitting to the destination node in the multicast routing method. delete delete The method of claim 8,
The repairing of the disconnected data transmission path may include resetting the data transmission path through periodic transmission and reception of control packets. The method of claim 11,
The resetting period of the data transmission path is variable according to the reception rate of the data packet.

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