KR101293159B1 - Broadcast packet transmission method and apparatus, and broadcast packet transmission and reception system in wireless ad hoc network - Google Patents

Abstract

Disclosed are a method and apparatus for transmitting a broadcast packet in a wireless ad hoc network, which prevents broadcast packet loss due to channel error or MAC frame collision during network broadcast using a relay node, and a broadcast packet transmission / reception system. In a method of transmitting a broadcast packet in a wireless ad hoc network, a transmitting node transmits a broadcast packet to a receiving node through a relay node in a wireless ad hoc network. In consideration, the 1-hop relay node is additionally selected to transmit the broadcast packet. Accordingly, as the number of relay nodes increases, the number of reception of relay nodes on a forward path of a network broadcast packet is improved, and the forwarding rate of broadcast packets is high, thus enabling reliable network broadcast.

Description

BROADCAST PACKET TRANSMISSION METHOD AND APPARATUS, AND BROADCAST PACKET TRANSMISSION AND RECEPTION SYSTEM IN WIRELESS AD HOC NETWORK}

The present invention relates to a broadcast packet transmission method and apparatus, and a broadcast transmission system, and more particularly, to a broadcast packet transmission method and apparatus for improving network broadcast transmission rate in a wireless ad hoc network, and a broadcast transmission / reception system. It is about.

A wireless ad hoc network is an autonomous network configured between nodes constituting the network. The wireless ad hoc network is freely able to move in and out as a node moves and does not have a communication infrastructure such as a base station or an access point. It is possible to communicate. Therefore, it is highly useful as a military tactical or emergency rescue network in areas where existing telecommunication facilities cannot be used due to wartime or large disasters. Since wireless ad hoc networks operate independently of the communication infrastructure, all nodes must act as terminals and routers. Therefore, even when the transmitting node and the receiving node are in a distance where direct communication is impossible, a routing protocol that enables multi-hop communication through other relay nodes plays an important role.

Routing protocols used in wireless ad hoc networks can be classified into on-demand routing protocols and table-driven routing protocols. On-demand routing protocol is a protocol that establishes a route by collecting necessary information immediately when route information is needed. On the other hand, the table-driven protocol is a protocol that nodes update their routing table by exchanging route information periodically even if route information is not needed right away. . Table-driven routing protocols have the advantage that the time taken to acquire route information is shorter than on-demand routing protocols, but the disadvantage is that the overhead for continuously updating the routing table is relatively high even when route information is not needed. .

One of the important problems in the routing protocol is network broadcast. Network broadcast refers to a form of packet transmission targeting an entire node constituting a network from one transmitting node. In the routing protocol, network broadcasts are used to convey neighbor node information or path discovery packets. The simplest way to implement a network broadcast is by flooding. Flooding is a method of retransmitting a packet when the destination address of the received packet is a packet whose broadcast address has not been received in the past. While the implementation is simple and there is no need for exchanging information with neighboring nodes, there is a disadvantage of low efficiency because all nodes constituting the network participate in retransmission of one broadcast packet. Optimized Link State Routing (OLSR), one of the table-driven routing protocols, introduced MPR (Multipoint Relay) to reduce the overhead of network broadcast of Topology Control (TC) packets required for routing table generation. . Each node selects some of the 1 hop neighbor nodes as MPR nodes so that it can cover all its 2 hop neighbor nodes at least once. The node selected as the MPR node retransmits only the first broadcast packet received from the node that has selected itself as the MPR node. Using the MPR node has the advantage of being able to broadcast to all nodes in the network with fewer transmission times than the flooding method in which all nodes participate in retransmission.

In the wireless ad hoc network using OLSR, the network broadcast using MPR can improve the efficiency by reducing the number of transmissions, but the weakness of transmission reliability remains. In a wireless environment where the link status is not stable, a small number of transmissions may be vulnerable when a reception failure occurs. In addition, the relay transmission using the MPR uses a broadcast in the medium access control (MAC) layer. The broadcast in the IEEE 802.11 MAC, which is widely used at present, is different from the unicast, which is a 1: 1 transmission. Since 4-way handshaking using To Send and Clear To Send (CTS) is not available, collisions due to hidden node problems in multi-hop transmission are likely to occur. In addition, since the MAC broadcast frame cannot use the MAC layer ACK, the collision probability is higher because the backoff window size is fixed. In addition to transmission failures for normal nodes, the ripple effect is even more severe when transmissions to MPR nodes fail. The MPR node plays a role of relaying the broadcast packet received to the neighboring nodes. If the MPR node fails to receive the MPR node, the MPR node cannot receive the broadcast packet.

1 is a view for explaining a broadcast packet transmission method of the conventional OLSR. As shown in FIG. 1, when the node 6 becomes a transmitting node and transmits a broadcast packet, the broadcast packet retransmission at node 9, which is a one-hop relay node of node 6, has failed. At this time, it can be seen that in the conventional OLSR relay method, nodes 8, 10, and 13 cannot receive broadcast packets.

Conventional OLSR discloses an MPR redundancy method for selecting an additional MPR to increase the transmission rate. This is to select the MPR node among the 1 hop neighbor nodes so that all 2 hop neighbor nodes are covered m times rather than 1. In some node deployment situations, the number or location of one-hop neighbor nodes is insufficient to cover all two-hop neighbor nodes m times, and some two-hop neighbor nodes may have fewer than m reception times. When using MAC protocol of Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) such as IEEE 802.11, additionally selected MPR nodes can cause frequent collisions at the MAC layer, resulting in a lower transmission rate. It can happen. Therefore, there is a need for a method of improving the transfer rate while suppressing the number of additionally selected MPRs.

Korea Patent Registration 10-0664953 ("Multicast Routing Method in Mobile Ad Hoc Network Environment", Samsung Electronics Co., Ltd., registered Dec. 28, 2006)

Accordingly, an object of the present invention is to provide a broadcast packet transmission method and apparatus in a wireless ad hoc network, and a broadcast packet transmission / reception system for preventing broadcast packet loss due to channel error or MAC frame collision when a network broadcast using a relay node. To provide.

In addition, another object of the present invention is to provide a broadcast packet transmission method and apparatus in a wireless ad hoc network that can additionally provide a reception opportunity for a two-hop relay node in order to improve network broadcast transmission rate in a wireless ad hoc network, and broadcast packet transmission and reception To provide a system.

The above-described object of the present invention provides a method for transmitting a broadcast packet in a wireless ad-hoc network, wherein the transmitting node transmits a broadcast packet to a receiving node through a relay node in a wireless ad-hoc network. The node may additionally select the 1-hop relay node in consideration of the number of reception of the 2-hop relay node to transmit the broadcast packet.

In accordance with another aspect of the present invention, there is provided a method of transmitting a broadcast packet in a wireless ad hoc network, the method comprising: selecting a relay node according to the transmission range by determining a transmission range of the broadcast packet; In addition to the one-hop relay node selected in the selecting step, selecting a one-hop neighbor node existing within a range capable of transmitting the broadcast packet to the two-hop relay node as an additional one-hop relay node; And transmitting the broadcast packet to a 1 hop relay node including the additional 1 hop relay node.

The additional 1 hop relay node selection step may include calculating a reception opportunity that the 2 hop relay node may have; Determining whether to add the one-hop relay node according to the reception opportunity; And in the determining step, selecting the one-hop relay node as an additional one-hop relay node when the one-hop relay node is added to the two-hop relay node. can do.

The selecting a relay node may include determining a broadcast packet transmission range; Receiving the broadcast packet relay information from the receiving node and the relay node existing within the transmission range; And selecting the relay node according to the relay information.

The receiving opportunity calculating step may include receiving reception opportunity information from the two hop relay node; And calculating a reception opportunity of a 2 hop relay node based on the reception opportunity information.

In the additional one-hop relay node selection step, the transmitting node is configured to prevent the broadcast packet from being excessively transmitted to the two-hop relay node by the additional one-hop relay node, so that the number of the additional one-hop relay nodes is increased. Can be limited to less than a certain number.

In the additional 1 hop relay node selection step, the transmitting node may limit the number of the additional 1 hop relay nodes in consideration of the arrangement status of the 2 hop relay node and whether a collision occurs in the MAC layer.

The transmitting node determines whether the two hop neighboring nodes of the transmitting node are all covered by the one hop relay node including the additional one hop relay node after the additional one hop relay node selection step, and if not, the additional one hop. You can return to the relay node selection step.

The determination of whether the two hop neighbor nodes are all covered may be determined by how many reception opportunities (m times) the two hop neighbor node has by the one hop relay node including the additional one hop relay node. .

The broadcast packet transmission method in the wireless ad-hoc network according to the present invention may further include the step of retransmitting the broadcast packet to the two-hop relay node by a one-hop relay node including the additional one-hop relay node.

An apparatus for transmitting a broadcast packet in a wireless ad hoc network according to the present invention is an apparatus in which a transmitting node transmits a broadcast packet to a receiving node through a relay node in a wireless ad hoc network, wherein the transmitting node is a 2-hop relay node. The broadcast packet may be transmitted by additionally selecting a 1-hop relay node in consideration of the number of times of reception.

An apparatus for transmitting a broadcast packet in a wireless ad hoc network according to the present invention includes: a relay node selecting unit which selects the relay node according to the transmission range by determining a transmission range of the broadcast packet; An additional one-hop relay node selecting unit configured to select, as an additional one-hop relay node, a one-hop neighbor node existing within a range capable of transmitting the broadcast packet to the two-hop relay node, in addition to the one-hop relay node selected in the selecting step; And a transmitter for transmitting the broadcast packet to a one-hop relay node including the additional one-hop relay node.

The additional 1 hop relay node selector may include: a reception opportunity calculator configured to calculate a reception opportunity that the 2 hop relay node may have; An addition decision unit determining whether to add the one-hop relay node according to the reception opportunity; And a selection unit for selecting, as an additional 1 hop relay node, a 1 hop neighbor node existing within a range capable of transmitting the broadcast packet to the 2 hop relay node when it is determined that the 1 hop relay node should be added in the determination step. can do.

The relay node selecting unit comprises: a transmission range determining unit which determines the broadcast packet transmission range; A relay information receiver configured to receive the broadcast packet relay information from the receiving node and the relay node existing within the transmission range; And a selecting unit for selecting the relay node according to the relay information.

The reception opportunity calculator comprises: an opportunity information receiver configured to receive reception opportunity information from the 2 hop relay node; And a calculator configured to calculate a reception opportunity of a 2 hop relay node based on the reception opportunity information.

The additional 1 hop relay node selector limits the number of the additional 1 hop relay nodes to less than a predetermined number to prevent the broadcast packet from being excessively transmitted to the 2 hop relay node by the additional 1 hop relay node. can do.

The additional 1 hop relay node selector may limit the number of additional 1 hop relay nodes in consideration of the arrangement of the 2 hop relay nodes and whether a collision occurs in the MAC layer.

The additional 1 hop relay node selector selects the additional 1 hop relay node, and then determines whether the 2 hop neighbor nodes of the transmitting node are all covered by the 1 hop relay node including the additional 1 hop relay node. If not, the additional 1 hop relay node may be further selected.

The determination of whether the two hop neighbor nodes are all covered may be determined by how many reception opportunities (m times) the two hop neighbor node has by the one hop relay node including the additional one hop relay node. .

In the apparatus for transmitting a broadcast packet in a wireless ad hoc network according to the present invention, a 1 hop relay node including the additional 1 hop relay node may retransmit the broadcast packet to the 2 hop relay node.

A system for transmitting and receiving a broadcast packet in a wireless ad hoc network according to the present invention is a system in which a transmitting node transmits and receives a broadcast packet to a receiving node through a relay node in a wireless ad hoc network, wherein the transmitting node is a 2-hop relay node. The broadcast packet may be transmitted by additionally selecting a 1-hop relay node in consideration of the number of times of reception.

The packet transmission / reception system determines a range for transmitting the broadcast packet, selects the relay node according to the transmission range, and exists within a range capable of transmitting the broadcast packet to the two-hop relay node in addition to the selected one-hop relay node. A transmitting node for transmitting the broadcast packet to a one-hop relay node including the additional one-hop relay node after selecting a one-hop neighbor node as an additional one-hop relay node; A relay node receiving the broadcast packet from the transmitting node and retransmitting the broadcast packet to the receiving node; And a receiving node receiving the broadcast packet from the relay node.

According to the method and apparatus for transmitting a broadcast packet in a wireless ad hoc network, and a broadcast packet transmission / reception system of the present invention, as the number of relay nodes increases, the number of reception of relay nodes on a transmission path of network broadcast packets is improved. As a result, the transmission rate of the broadcast packet is increased, thereby enabling reliable network broadcast.

In addition, the broadcast packet transmission method and apparatus in the wireless ad hoc network of the present invention, and the broadcast packet transmission and reception system, because it operates in an ad hoc network that operates independently from the existing communication infrastructure, the military tactical communication terminal or disaster area There is an effect that can be utilized in wireless equipment for emergency communication.

1 is a view for explaining a broadcast packet transmission method of the conventional OLSR method;
2 is a view for explaining a broadcast packet transmission method of a wireless ad hoc network according to an embodiment of the present invention;
3 is a flowchart schematically illustrating a broadcast packet transmission method in a wireless ad hoc network according to another embodiment of the present invention;
4 is a block diagram schematically illustrating an apparatus for transmitting broadcast packets in a wireless ad hoc network according to another embodiment of the present invention;
5 is a block diagram schematically illustrating a system for transmitting and receiving broadcast packets in a wireless ad hoc network according to another embodiment of the present invention;
FIG. 6 is a graph comparing end-to-end delay between the broadcast packet transmission method and the conventional method in the wireless ad hoc network according to the present invention; FIG.
7 is a graph comparing the transmission rate performance when applying the broadcast packet transmission method in the wireless ad hoc network according to the present invention and when applying the conventional method,
8 is a graph comparing the number of retransmissions of a relay node when a broadcast packet transmission method in a wireless ad hoc network according to the present invention is applied and when a conventional method is applied;
9 is a graph comparing the average number of receptions of a relay node when a broadcast packet transmission method in a wireless ad hoc network according to the present invention is applied and when a conventional method is applied;
10 is a graph comparing the effect of one additional relay node on the number of receptions when the broadcast packet transmission method is applied in the wireless ad hoc network according to the present invention and when the conventional method is applied.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

2 is a view for explaining a broadcast packet transmission method of a wireless ad hoc network according to an embodiment of the present invention. As shown in Fig. 2, node 6 is a transmitting node, and there are nodes 2, 3, 4, 5, 7, 9 as one-hop neighbor nodes. Also, two hop neighbor nodes are nodes 1, 10, 11, and 12.

First, node 6 is selected as the relay node (MPR) in the order in which the node 6 has links with the most two-hop neighbor nodes among its one-hop neighbor nodes. Nodes 9 and 4 are defined as one-hop MPRs or one-hop relay nodes because they are one hop apart from node 6. Node 9 also selects a relay node from among its 1-hop neighbor nodes. In this case, node 10, which can cover nodes 8 and 13, which are 2 hop neighbor nodes of node 9, is selected as a relay node. Node 10 is a relay node of node 9, and is defined as two-hop MPR or two-hop relay node because it is two hops apart from node 6. When the node 6 receives the hello message of the node 9, the node 6 confirms that the node 10 is selected as the relay node and knows that the node 10 is its two-hop relay node.

When applying the broadcast packet transmission method in the wireless ad-hoc network of the present invention, additional relay nodes are selected in the following order. Node 6 calculates how many receive opportunities the two-hop relay node has when it sends a broadcast packet. In this embodiment, since only the node 9 can be transmitted, there is one reception opportunity. Node 6 looks for nodes that can transmit to node 10 among its 1-hop neighbors (nodes 2, 3, 5, and 7) that are not selected as relay nodes in order to give node 10, a 2 hop relay node, more opportunities for reception. As a result, node 5 is selected as an additional one-hop relay node.

When the additional relay node is selected by using the broadcast packet transmission method of the present invention, when the transmitting node, that is, node 6 transmits the broadcast packet, the packet is delivered through the following process. First, nodes 1, 2, 3, 4, 5, 7, and 9, which are the first hop neighbors of node 6, receive the broadcast packet of node 6. Since nodes 4, 5, and 9 are relay nodes of node 6, the broadcast packets just received are retransmitted to neighboring nodes. The retransmission of these relay nodes forwards the broadcast packets of node 6 to nodes 1, 10, 11, and 12, which are two hop neighbor nodes of node 6. Node 10 is a relay node of node 9 and a two-hop relay node of node 6 that can receive broadcast packets twice from node 5 and node 9.

Referring to the method of FIG. 1, assuming that node 10 fails to receive a broadcast packet when the node 9 retransmits the broadcast packet, nodes 8, 10, and 13 cannot receive broadcast packets in the conventional OLSR broadcast packet transmission method. (See Figure 1).

However, if node 5 is selected as an additional 1-hop relay node by using the broadcast packet transmission method of the present invention, node 10 will have a chance to receive broadcast packets from node 5 one more time, so that it will be able to recover from the previous reception failure. As a result, it can forward broadcast packets to nodes 8 and 13.

3 is a flowchart schematically illustrating a broadcast packet transmission method of a wireless ad hoc network according to an embodiment of the present invention. As shown in FIG. 3, in the method of transmitting a broadcast packet in a wireless ad hoc network, the method of determining a mallet range of a broadcast packet and selecting a relay node 310 calculates a reception opportunity that a two-hop relay node may have. Step 320, determining whether to add a 1-hop relay node according to the receiving opportunity (330) and selecting (340) a 1-hop neighbor node capable of transmitting a packet to the 2-hop relay node as an additional 1-hop relay node, and Transmitting 350 a broadcast packet to a one-hop relay node including an additional one-hop relay node.

In the relay node selection step 310, the transmitting node determines the range to which the broadcast packet should be transmitted, and determines a node to receive the broadcast packet. More specifically, in step 310, the transmitting node determines the broadcast packet transmission range. Broadcast packet relay information is received from a receiving node and a relay node existing within a transmission range. The total relay node including the 1-hop and 2-hop relay nodes is selected according to the received relay information. At this time, the selected relay node is a node existing between the transmitting node and the receiving node to transmit the broadcast packet to the receiving node at the shortest distance. The receiving node may receive the broadcast packet through several relay nodes, or the 1-hop neighbor node of the transmitting node may be the receiving node without the relay node.

In the reception opportunity calculation step 320, the transmitting node calculates how much of the relay node selected in the relay node selection step 310 the opportunity to receive the broadcast packet from the one-hop relay node. The transmitting node receives the reception opportunity information including the number of neighboring one hop relay nodes from the two hop relay node. Subsequently, a reception opportunity for receiving a broadcast packet by the 2-hop relay node is calculated based on the reception opportunity information. If there are many one-hop relay nodes transmitting broadcast packets to two-hop relay nodes, there will be more opportunities for reception by the two-hop relay nodes. Accordingly, the reception opportunity calculation step 320 is to determine the maximum reception opportunity of the two hop nodes in order to prevent the additional one hop relay node from being selected more than necessary.

In step 330 of determining whether to add a 1 hop relay node, the transmitting node plays a role of determining whether an additional 1 hop relay node is required according to the reception opportunity calculated in the reception opportunity calculation step 320. As mentioned above, if a two-hop relay node has many opportunities to receive broadcast packets from the one-hop relay node, no additional one-hop relay node is needed. Conversely, for some two-hop relay nodes, if there are not many one-hop relay nodes around and there are few reception opportunities, then an additional one-hop relay node is needed. Thus, in this case, the transmitting node determines that an additional one hop relay node is needed.

Next, in the step of selecting an additional 1 hop relay node 340, if it is determined that an additional 1 hop relay node is needed, the transmitting node selects an additional 1 hop relay node capable of transmitting broadcast packets to the 2 hop relay node. If it is determined in step 330 that the 1-hop relay node is not added, the transmitting node will send the broadcast packet directly to the 1-hop relay node without going through this step. If it is determined that an additional one hop relay node is needed, then in step 340, a suitable additional one hop relay node capable of transmitting broadcast packets to the two hop relay node is selected. Since the additional 1 hop relay node must receive the broadcast packet from the transmitting node, it becomes one of the 1 hop neighbor nodes of the transmitting node. In addition, since the broadcast packet received to the two-hop relay node must be transmitted, it must be within a transmission range from the two-hop relay node. Therefore, the transmitting node selects the one-hop neighbor node of the transmitting node capable of transmitting the broadband packet to the two-hop relay node as an additional one-hop relay node. At this time, if the number of additional one-hop relay node is selected, the number of reception of the two-hop relay node may be increased, but in terms of transmission efficiency, the amount of packet transmission increases, which is not good. In addition, as described above, collisions in the MAC layer may be more frequent, which may result in a lower transmission rate. Therefore, the transmitting node needs to limit the number of additional one-hop relay nodes to an appropriate number so that collision in the MAC layer does not occur according to the arrangement of the two-hop relay nodes.

In addition, after the additional 1 hop relay node selection step 340, the broadcast packet transmission method of the wireless ad hoc network determines whether all 2 hop neighbor nodes of the transmitting node are covered by the 1 hop relay node. At this time, if it is determined that the two hop neighbor nodes are all covered by the one-hop relay node, the process proceeds to the next transmission step 350, and if it is determined that the coverage is not covered, the additional one-hop relay node is selected again (step 340). You will return to select additional 1-hop relay nodes. The determination of whether the 2 hop neighbor node is covered may be determined based on whether the 2 hop neighbor node may have m or more reception opportunities due to the additional 1 hop relay node.

Finally, in the transmitting step 350, the transmitting node is to broadcast to the one-hop relay node selected in the relay node selection step 310 and the additional one-hop relay node selected in the additional one-hop relay node selection step 340. Send a cast packet. According to the present invention, since the broadcast packet is also transmitted to the selected 1-hop relay node, the reception reliability at the 2-hop relay node is improved.

4 is a block diagram schematically illustrating an apparatus for transmitting broadcast packets in a wireless ad hoc network according to an embodiment of the present invention. As shown in FIG. 4, the apparatus for transmitting a broadcast packet in a wireless ad hoc network includes a relay node selecting unit 410, a reception opportunity calculating unit 420, an addition determining unit 430, and an additional 1 hop relay node selecting unit. 440 and the transmitter 450 may be included.

The relay node selecting unit 410 determines a range in which the broadcast packet should be transmitted, and determines a node to receive the broadcast packet. Node selection takes the form of selecting a relay node existing between a transmitting node and a receiving node that enables the transmission of the broadcast packet to the receiving node at the shortest distance. The relay node selecting unit 410 determines the broadcast packet transmission range. Then, the broadcast packet relay information is received from the receiving node and the relay node existing within the transmission range. The total relay node including the 1-hop and 2-hop relay nodes is selected according to the received relay information.

The reception opportunity calculator 420 calculates how many 2-hop relay nodes have an opportunity to receive broadcast packets from the 1-hop relay node among the relay nodes selected by the relay node selector 410. By counting the number of one-hop relay nodes around the two-hop relay node, the number of times a two-hop relay node receives a broadcast packet can be calculated. The reception opportunity calculator 420 first receives the reception opportunity information including the number of neighboring one hop relay nodes from the two hop relay node. Subsequently, a reception opportunity for receiving a broadcast packet by the 2-hop relay node is calculated based on the reception opportunity information.

The addition decision unit 430 determines whether an additional 1-hop relay node is required according to the reception opportunity calculated by the reception opportunity calculator 420. As described above, the 2 hop relay node may or may not need an additional 1 hop relay node depending on the number of receptions. Accordingly, the addition determining unit 430 determines that an additional 1 hop relay node is required for the 2 hop relay node with a low number of reception, and determines that an additional 1 hop relay node is not required for the 2 hop relay node with a large number of reception times.

The additional one-hop relay node selector 440 may further transmit a broadcast packet to the two-hop relay node when the additional decision determiner 430 determines that the two-hop relay node needs an additional one-hop relay node. It selects the hop relay node. If the additional decision determiner 430 determines that the additional one-hop relay node is not necessary, the additional one-hop relay node selector 440 does not need to operate. The transmitting node will then send a broadcast packet directly to the 1 hop relay node. If the additional decision determiner 430 determines that a one-hop relay node is required, the additional one-hop relay node selector 440 selects a suitable additional one-hop relay node capable of transmitting broadcast packets to the two-hop relay node. Done. The additional 1 hop relay node selector 440 selects a 1 hop neighbor node of a transmitting node capable of transmitting a broadband packet to the 2 hop relay node as an additional 1 hop relay node. As described above, if the additional one-hop relay node is selected too many times, the number of reception of the two-hop relay node may be increased, but in terms of transmission efficiency, the amount of packet transmission increases, which is not good. Conflicts at the MAC layer can be frequent, resulting in lower transmission rates. Accordingly, the additional 1-hop relay node selector 440 selects the number of additional 1-hop relay nodes by limiting the number of additional 1-hop relay nodes to an appropriate number according to the arrangement of the 2-hop relay nodes. The additional 1 hop relay node selector 440 determines whether all 2 hop neighbor nodes of the transmitting node are covered by the 1 hop relay node. At this time, if it is determined that all of the two hop neighbor nodes are covered by the one-hop relay node, the process proceeds to the transmission unit 450 and transmits the broadcast packet to the one-hop relay node. Return to the selector 440 to further select the additional one-hop relay node. The determination of whether the 2 hop neighbor node is covered may be determined based on whether the 2 hop neighbor node may have a reception opportunity m or more times due to the additional 1 hop relay node.

The transmitter 450 transmits a broadcast packet to be transmitted to the 1-hop relay node selected by the relay node selector 410 and the additional 1-hop relay node selected by the additional 1-hop relay node selector 440. According to the present invention, since the broadcast packet is also transmitted to the selected 1-hop relay node, the reception reliability at the 2-hop relay node is improved.

5 is a block diagram schematically illustrating a system for transmitting and receiving broadcast packets in a wireless ad hoc network according to another embodiment of the present invention. As shown in FIG. 5, the system for transmitting and receiving a broadcast packet in a wireless ad hoc network includes a transmitting node 510 transmitting a broadcast packet and a relay node 520 receiving the broadcast packet from the transmitting node and retransmitting the received packet to the receiving node. And a receiving node 530 that receives the broadcast packet.

As described above, the transmitting node 510 additionally selects a one-hop relay node in consideration of the number of reception of the two-hop relay node and transmits a broadcast packet. The transmitting node 510 first selects a relay node 520 according to a transmission range by determining a range to transmit a broadcast packet. Then, the two-hop relay node 523 of the selected relay nodes calculates a reception opportunity to receive the broadcast packet from the one-hop relay node 521 which has been conventionally selected. It is determined whether to add the 1 hop relay node 522 according to the reception opportunity. If it is determined that the 1 hop relay node should be added, the 1 hop neighbor node existing within the range capable of transmitting the broadcast packet to the 2 hop relay node 523 is selected as the additional 1 hop relay node 522. Thereafter, the transmitting node 510 transmits the broadcast packet to the one-hop relay node including the conventional one-hop relay node 521 and the additional one-hop relay node 522.

The relay node 520 receives the broadcast packet from the transmitting node and retransmits the broadcast packet to the receiving node 530.

The receiving node 530 receives a broadcast packet from the relay node 520.

FIG. 6 is a graph comparing end-to-end delays when applying a broadcast packet transmission method in a wireless ad hoc network according to the present invention and when applying a conventional method. The FER (Frame Error Rate) is set to 0%, 10%, 50%. As shown in FIG. 6, both the broadcast packet transmission method and the conventional broadcast packet transmission method in the wireless ad hoc network according to the present invention show that the delay is gradually increased as the number of nodes increases. Here, it can be seen that the broadcast packet transmission method in the wireless ad hoc network according to the present invention has a maximum delay value of 5 ms. Therefore, it can be analyzed that as the number of nodes increases, the weight of nodes located in a location that can be transmitted through several relay nodes increases rather than a node located in a neighbor, thereby increasing the overall delay.

7 is a graph comparing transmission rate performance when a broadcast packet transmission method is applied to a wireless ad hoc network according to the present invention and when a conventional method is applied. As described above, the frame error rate (FER) is set to 0%, 10%, and 50%. As shown in FIG. 7, as the number of nodes increases, the density of nodes increases, so that the transfer rate tends to increase. When the number of nodes exceeds 90, the rate of increase in transfer rate decreases. When the FER is 0%, the broadcast packet transmission method in the wireless ad hoc network according to the present invention shows a slightly lower rate. However, when the FER is 10%, the difference is reduced so that the FER is 50%. It can be seen that the broadcast packet transmission method in the wireless ad hoc network shows a transmission rate performance of about 1% higher than that of the conventional method.

8 is a graph comparing the number of retransmissions of a relay node when a broadcast packet transmission method in a wireless ad hoc network according to the present invention is applied and when a conventional method is applied. As shown in FIG. 8, the broadcast packet transmission method in the wireless ad-hoc network according to the present invention can confirm that the increase in the number of retransmissions decreases as the relay node coverage increases as compared to the MPR redundancy method (ROLSR). Therefore, if the coverage of the relay node is increased, the broadcast packet transmission method in the wireless ad-hoc network according to the present invention can reduce the number of retransmissions and efficiently transmit the broadcast packet.

9 is a graph comparing the average number of receptions of a relay node when a broadcast packet transmission method in a wireless ad hoc network according to the present invention is applied and when a conventional method is applied. As shown in FIG. 9, it can be seen that the broadcast packet transmission method in the wireless ad-hoc network according to the present invention shows a performance close to the ROLSR in the average number of receptions of the relay node.

10 is a graph comparing the effect of one additional relay node on the number of receptions when the broadcast packet transmission method is applied in the wireless ad hoc network according to the present invention and when the conventional method is applied. This represents how much the number of receptions is improved when one relay node is additionally selected compared to the relay node selected by the conventional OLSR method. As shown in FIG. 10, it can be seen that the broadcast packet transmission method in the wireless ad-hoc network according to the present invention improves the number of receptions due to the additionally selected relay node compared to the ROLSR, thus increasing transmission efficiency. Able to know.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions as defined by the following claims It will be understood that various modifications and changes may be made thereto without departing from the spirit and scope of the invention.

Claims (22)

A method for transmitting broadcast packets to a receiving node through a relay node in a wireless ad hoc network, the method comprising:
The transmitting node transmits the broadcast packet by additionally selecting the 1-hop relay node in consideration of the number of reception of the 2-hop relay node.
Selecting a relay node according to the transmission range by determining a range to transmit the broadcast packet;
In addition to the one-hop relay node selected in the selecting step, selecting a one-hop neighbor node existing within a range capable of transmitting the broadcast packet to the two-hop relay node as an additional one-hop relay node; And
And transmitting the broadcast packet to a one-hop relay node including the additional one-hop relay node.
delete The method of claim 1, wherein the additional 1 hop relay node selection step,
Calculating a reception opportunity that the two hop relay node may have;
Determining whether to add the one-hop relay node according to the reception opportunity; And
If it is determined in the determining step that the one-hop relay node should be added, selecting a one-hop neighbor node existing within a range capable of transmitting the broadcast packet to the two-hop relay node as an additional one-hop relay node. Broadcast packet transmission method in a wireless ad hoc network, characterized in that.
The method of claim 1, wherein the relay node selection step,
Determining the broadcast packet transmission range;
Receiving the broadcast packet relay information from the receiving node and the relay node existing within the transmission range; And
And selecting the relay node according to the relay information.
The method of claim 3, wherein the receiving opportunity calculation step,
Receiving reception opportunity information from the two hop relay node; And
And calculating a reception opportunity of a two-hop relay node based on the reception opportunity information.
4. The method of claim 3, wherein in the further one hop relay node selection step:
In order to prevent the transmitting node from excessively transmitting the broadcast packet to the two-hop relay node by the additional one-hop relay node, the number of the additional one-hop relay nodes is limited to less than a predetermined number. Broadcast packet transmission in a wireless ad hoc network.
7. The method of claim 6, wherein in the further one hop relay node selection step:
The method of claim 1, wherein the transmitting node limits the number of the additional 1-hop relay nodes in consideration of the arrangement of the 2 hop relay nodes and whether a collision occurs in a MAC layer.
The method of claim 1, wherein the transmitting node is
After the additional one-hop relay node selection step, it is determined whether two neighboring nodes of the transmitting node are all covered by the one-hop relay node including the additional one-hop relay node, and if not, the selection of the additional one-hop relay node. A method of transmitting broadcast packets in a wireless ad hoc network, characterized by returning to.
The method of claim 8,
The determination as to whether the 2 hop neighbor node is covered is determined by how many reception opportunities (m times) the 2 hop neighbor node has by the 1 hop relay node including the additional 1 hop relay node. Broadcast packet transmission in a wireless ad hoc network.
The method of claim 1, wherein the packet transmission method,
And retransmitting the broadcast packet to the two-hop relay node by a one-hop relay node including the additional one-hop relay node.
An apparatus for transmitting a broadcast packet to a receiving node through a relay node in a wireless ad hoc network, the apparatus comprising:
The transmitting node transmits the broadcast packet by additionally selecting the 1-hop relay node in consideration of the number of reception of the 2-hop relay node.
A relay node selecting unit configured to select a range for transmitting the broadcast packet and select the relay node according to the transmission range;
An additional one-hop relay node selecting unit configured to select, as an additional one-hop relay node, a one-hop neighbor node existing within a range capable of transmitting the broadcast packet to the two-hop relay node, in addition to the one-hop relay node selected in the selecting step; And
And a transmitter for transmitting the broadcast packet to a one-hop relay node including the additional one-hop relay node.
delete The method of claim 11, wherein the additional 1 hop relay node selector,
A reception opportunity calculator configured to calculate a reception opportunity that the two hop relay node may have;
An addition decision unit determining whether to add the one-hop relay node according to the reception opportunity; And
In the determining step, if it is determined that the one-hop relay node should be added, a selection unit for selecting a one-hop neighbor node existing within the range capable of transmitting the broadcast packet to the two-hop relay node as an additional one-hop relay node. Broadcast packet transmission apparatus in a wireless ad hoc network, characterized in that.
The method of claim 11, wherein the relay node selecting unit,
A transmission range determining unit which determines the broadcast packet transmission range;
A relay information receiver configured to receive the broadcast packet relay information from the receiving node and the relay node existing within the transmission range; And
And a selecting unit which selects the relay node according to the relay information.
The method of claim 13, wherein the reception opportunity calculation unit,
An opportunity information receiver configured to receive reception opportunity information from the 2 hop relay node; And
And a calculator configured to calculate a reception opportunity of a two-hop relay node based on the reception opportunity information.
The method of claim 11, wherein the additional 1 hop relay node selector,
In order to prevent the broadcast packet from being excessively transmitted to the two-hop relay node by the additional one-hop relay node, the number of the additional one-hop relay nodes is limited to a wireless ad hoc network. Device for sending broadcast packets.
The method of claim 16, wherein the additional 1 hop relay node selector,
The apparatus for transmitting a broadcast packet in a wireless ad hoc network, wherein the number of the additional 1 hop relay nodes is limited in consideration of the arrangement of the 2 hop relay nodes and whether a collision occurs in a MAC layer.
The method of claim 11,
After the additional 1 hop relay node selector selects the additional 1 hop relay node, it is determined that the 2 hop neighbor nodes of the transmitting node are all covered by the 1 hop relay node including the additional 1 hop relay node and not covered. And if not, further selecting the additional one-hop relay node.
The method of claim 18,
The determination as to whether the two hop neighbor nodes are all covered is determined by how many reception opportunities (m times) the two hop neighbor node has by the one hop relay node including the additional one hop relay node. Broadcast packet transmission apparatus in a wireless ad-hoc network.
The method of claim 11,
And a one-hop relay node including the additional one-hop relay node retransmits the broadcast packet to the two-hop relay node.
A system in which a transmitting node transmits and receives a broadcast packet to a receiving node through a relay node in a wireless ad hoc network,
The transmitting node transmits the broadcast packet by additionally selecting the 1-hop relay node in consideration of the number of reception of the 2-hop relay node.
A one-hop neighbor node which is within a range capable of transmitting the broadcast packet to the two-hop relay node in addition to the selected one-hop relay node by selecting the relay node according to the transmission range by determining a range to transmit the broadcast packet. A transmitting node for transmitting the broadcast packet to a one-hop relay node including the additional one-hop relay node after selecting as an additional one-hop relay node;
A relay node receiving the broadcast packet from the transmitting node and retransmitting the broadcast packet to the receiving node; And
And a receiving node for receiving the broadcast packet from the relay node. delete

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