KR100845675B1 - Method for configuring routing path in a wireless ad-hoc network - Google Patents

Abstract

A routing method in a wireless ad-hoc network is provided to smoothly offer modern multimedia services by considering a non-directional radio channel and multi-hop characteristics more exactly in finding out a path which can support a bandwidth required between a source node and a destination node in a wireless ad-hoc network using an IEEE 802.11 wireless interface. A source node broadcasts an RREQ(Routing Request) message to neighbor nodes in order to find out a path having a sufficient bandwidth to a destination node(S100). Receiving the RREQ message, each neighbor node records routing information, contained in the RREQ message, in its own routing table, and calculates an available bandwidth, the minimum bandwidth, and a bandwidth required for new traffic(S200). Based on the calculated bandwidths, each neighbor node judges whether it satisfies a preset sufficient bandwidth condition(S300). In case an arbitrary neighbor node satisfies the preset sufficient bandwidth condition, the arbitrary neighbor node broadcasts the RREQ message to the next neighbor nodes(S400). Afterwards, if the RREQ message is transmitted up to the destination node(S600), the destination node transmits an RREP(Routing Response) message to the source node in unicast(S700). As the source node receives the RREP message, routing is completed(S800).

Description

METHOOD FOR CONFIGURING ROUTING PATH IN A WIRELESS AD-HOC NETWORK}

The present invention relates to a routing method in a wireless ad-hoc network (or wireless ad hoc network), and more particularly, a source node and a destination node in a wireless ad hoc network using an IEEE 802.11 wireless interface. The present invention relates to a path setting method for satisfying bandwidth in a wireless ad hoc network that can smoothly provide a modern multimedia service by finding a path that can support a required bandwidth therebetween.

In general, with the development of the Internet and mobile communication technology, the present society is able to receive various multimedia services regardless of time and space, which is causing a great change in the user's life environment.

In particular, as portable electronic devices such as notebook PCs and PDAs are gradually spread in recent years, efforts to implement data communication based on the Internet through wireless networks as well as wired networks have been increasing.

An example of such a wireless network is an ad-hoc network. The ad hoc network does not have a centralized management device, does not use an existing communication infrastructure, and does not have a fixed control device (eg, a router, a host, a wireless base station, etc.) for providing a connection between mobile nodes. . That is, according to the ad hoc network, the mobile node itself operates as a router.

Therefore, when a given mobile node intends to perform communication with a counterpart node, the mobile node must establish a communication path through various nodes located between the counterpart node. An example of such an ad hoc network is a sensor network composed of a plurality of sensors.

Recent developments in wireless communication enable the development of low-cost, low-power, multi-functional sensor nodes, enabling sensor networks consisting of these small sensor nodes to perform tasks such as sensing, data processing, and communication.

In other words, the sensor network is composed of numerous densely distributed sensor nodes. In order to collect and transmit desired information through these numerous sensor nodes, a routing protocol between sensor nodes composed of only wireless interfaces must be implemented. In addition, it should be possible to properly respond to the phenomena caused by the free movement of the sensor nodes.

In addition, wireless ad-hoc networks do not have the same fixed characteristics as conventional wired network infrastructures, but are characterized by being uncontrolled and often created in a spontaneous manner. This maintains control through a distributed concept. Nodes can be connected or disconnected in an uncontrolled manner compared to standard fixed network architectures, and the nodes can shuttle back and forth at high speed, which dramatically changes the network topology.

In some cases, such an ad hoc network is formed by the user / client device itself as an infrastructure component. This component is then actually a mobile station in the sense that the infrastructure moves accordingly as the user moves around, in and out of the network cell. This is a direct way to form the infrastructure, but sets very high demands on the routing protocol.

However, due to the nature of the wireless network, existing wired routing protocols cannot be used as it is, so mobiles such as Dynamic Source Routing (DSR), Ad hoc On-Demand Distance Vector Routing (AODV), and Temporally Ordered Routing Algorithm (TORA) Routing Protocol for ad hoc networks has been developed. These are proposed to find the shortest path between a source node and a destination node in a wireless network.

The conventional routing protocol mainly focuses on minimizing the hop count from one node to the destination node, and selects a path that minimizes the hop count as a transmission path.

However, since the environment between nodes may be different, even a path having the same hop number may not have the same transmission speed. Therefore, there is a problem in that the best transmission path cannot be selected simply by considering the number of hops.

As described above, in the wireless ad hoc network, the minimum hop distance routing scheme mainly considering only the best-effort service has been studied. Since then, research has been made on providing Quality of Service (QoS) (particularly, bandwidth) for multimedia services, and research on QoS has been made in the routing field. However, the QoS routing research in the wireless ad hoc network has not been considered in the wireless interface or does not accurately reflect the characteristics of the wireless channel.

In addition, the feature that the wireless communication channel is omni-directional and that the source node and the destination node can be connected through the multi-hop makes it difficult to find a path that satisfies the bandwidth in the wireless ad hoc network.

In the case of a protocol that finds a path that satisfies the existing bandwidth, there is a problem in that it calculates that more bandwidth is required for a new traffic connection or does not determine that even though the wireless ad hoc network can accommodate the new traffic. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to provide an omni-directional radio channel through a path capable of supporting a required bandwidth between a source node and a destination node in a wireless ad hoc network using an IEEE 802.11 air interface. The present invention provides a path setting method that satisfies bandwidth in a wireless ad hoc network that can provide a modern multimedia service smoothly by finding and considering the multi-hop characteristics.

In order to achieve the above object, a first aspect of the present invention provides a routing method for transmitting traffic between a source node and a destination node in a wireless Ad-hoc network, the method comprising: (a) Broadcasting a route request (RREQ) message to a destination node; (b) calculating, by neighbor nodes receiving the broadcast routing request message, an available bandwidth, a minimum bandwidth, and a required bandwidth value of new traffic; (c) determining whether each neighboring node satisfies a preset sufficient bandwidth condition according to the hop distance from the source node and the destination node using the calculated respective bandwidth values; (d) if the sufficient bandwidth condition is satisfied as a result of the determination in step (c), broadcasting the route establishment request message to the next neighbor nodes; And (e) repeating the steps (b) to (d), when the routing request message is transmitted to the corresponding destination node, the destination node transmits a routing setup response (RREP) message to the source node. It provides a method for routing in a wireless ad hoc network comprising the steps.

Here, it is preferable that when the neighboring nodes do not satisfy the sufficient bandwidth condition as a result of the determination in step (c), the received path establishment request message is discarded.

Advantageously, said routing request message includes parameter values necessary to check said sufficient bandwidth condition.

A second aspect of the present invention provides a recording medium having recorded thereon a program for executing the route setting method in the above-described wireless ad hoc network.

According to the path setting method in the wireless ad hoc network of the present invention as described above, in the wireless ad hoc network using the IEEE 802.11 wireless interface, a path that can support the required bandwidth between the source node and the destination node is a non-directional radio Finding more accurately considering channel and multi-hop characteristics, there is an advantage that can smoothly provide modern multimedia services.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention illustrated below may be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

1 is a flowchart illustrating a path setting method in a wireless ad hoc network according to an embodiment of the present invention.

Referring to FIG. 1, in the method for routing a wireless ad hoc network according to an embodiment of the present invention, a source node (or a source node) is selected from among a plurality of nodes having a wireless interface. In the case where it is desired to transmit predetermined information to a destination node (or a destination node), if the distance between the nodes is too large and direct transmission is impossible, the information may be transmitted through other nodes located therebetween.

In other words, it establishes a path through the nodes located between them and transmits the information through the path. This route establishment is accomplished by exchanging a Route Request (RREQ) message and a Route Reply (RREP) message.

In this case, the routing request (RREQ) message is a message used by the source node to find a destination node, that is, to request the creation of a route, and the routing response (RREP) message is sent to the routing request (RREQ) message. Is the response message. That is, if the node receiving the RREQ message is the destination node or knows the routing path to the destination node, the node in response to this is the unicast scheme. The RREQ message is transmitted to the source node that first transmitted.

Meanwhile, the basic operation of the QoS (Quality of Service) routing protocol for the multimedia service proposed by the present invention is similar to a typical AODV (Ad hoc On-demand Distance Vector) routing protocol.

That is, in order for the source node to find a path having sufficient bandwidth to the destination node, the source node first broadcasts a Route Request (RREQ) message to neighboring neighbor nodes connected thereto ( S100).

At this time, a type field (Type), J, R, G, D, U field information and reserved fields (Reserved), and a corresponding path setting request (RREQ) message are transmitted to the path setting request (RREQ) message. There is a field for counting and storing the hop number (Hop Count), and the ID (RREQ ID) for identifying a RREQ message, the IP address of the destination node, the sequence number of the destination node, and the corresponding path setting request. (RREQ) includes routing information such as the IP address and sequence number of the source node that sent the message. In addition, it is preferable that the RREQ message includes various parameter values necessary for checking a sufficient bandwidth condition to be described later.

Next, when the neighboring nodes receive a routing request (RREQ) message broadcasted from the source node, the routing information included in the routing request (RREQ) message is recorded in its routing table. The available bandwidth B _available , the minimum bandwidth B _min , and the required bandwidth B _req of new traffic are calculated (S200), and the hop distance from the source node using the calculated bandwidth values is calculated. And satisfies a preset sufficient bandwidth condition according to the destination node (S300).

As a result of the determination in step S300, when the neighboring nodes satisfy the sufficient bandwidth condition, that is, when the current node has sufficient bandwidth, the RREQ message is broadcast to the next neighboring nodes ( Broadcast) to transmit (S400). Meanwhile, if the sufficient bandwidth condition is not satisfied, the received route establishment request (RREQ) message is discarded (S500).

Subsequently, when the path setting request (RREQ) message is transmitted to the destination node by performing the steps S200 to S500 repeatedly (S600), the destination node sets the path in response to the path setting request (RREQ) message. A response (RREP) message is transmitted to the source node (Unicast) (S700), when the source node receives the routing response (RREP) message, the path setting is completed (S800).

Meanwhile, when a plurality of RREQ messages transmitted through different paths arrive at the destination node, the destination node transmits a RREP message to the RREQ message that arrived first. The remaining routing request (RREQ) message is preferably discarded.

Hereinafter, a sufficient bandwidth condition including a method of calculating available bandwidth B _available , minimum bandwidth B _min , and required bandwidth B _req values of new traffic applied to an embodiment of the present invention will be described in detail. Let's do it.

First, in order to find a path that satisfies the bandwidth in the present invention, information on how much traffic is transmitted along which path in the current network, and how much radio resources when the traffic to be newly set up is transmitted along the path A pre-calculation process is needed on whether to consume it.

That is, the bandwidth required when traffic due to the data flow between source node i and destination node j is transmitted between one-hop nodes (nodes l and m), i.e., the required bandwidth of new traffic B _{req, (l, m)} (i , j) can be calculated by the following Equation 1.

Here, R (i, j) means the packet generation time interval of the traffic, the B _channel means the transmission rate of the Institute of Electrical & Electronics Engineers (IEEE) 802.11 wireless interface.

In addition, the T _{data, (l, m)} (i, j) is the time required to transmit data, IEEE 802.11 Medium Access Control (MAC) frame loss probability between 1-hop nodes (nodes l and m) When considering (P _{DATA, (l, m)} ) and when not using the Request to Send (RTS) / Clear to Send (RTS) mechanism, the following equation is used.

Here, h is a limit value of retransmission when MAC frame loss is defined in the IEEE 802.11 standard. In addition, _{T'c, DATA, (l, m)} is calculated by Equation 3 below as a time consumed when a collision occurs when transmitting a MAC frame.

Here, T _difs and T _{ACKTimeout mean} a DIFS value defined in the IEEE 802.11 standard and a timeout value of an ACK frame.

In addition, T _{'s, DATA, (l, m)} is calculated by Equation 4 below as a time consumed when the MAC frame is successfully transmitted.

Here, the H means the length of the header, the L (i, j) means the length of the packet, the T _ack means the time spent transmitting the ACK frame of the IEEE 802.11 MAC, the T _sifs Means SIFS time in IEEE 802.11 standard.

In addition, T _CW (k) in Equation 2 represents a backoff time according to the number k of attempts to retransmit the MAC frame, and can be obtained by Equation 5 below.

Here, the CW _min and CW _max means the minimum value and the maximum value of the backoff time in the IEEE 802.11 standard, respectively, and the T _SlotTime means the slot time in the IEEE 802.11 standard.

The bandwidth BUT (l, m) consumed in the link connecting two nodes l and m is calculated by Equation 6 below.

Here, N (l) means a one-hop neighbor node of node l, and Next (i, j) is the next node in the routing table at node l for traffic flows where source node is i and destination node is j It means (Next Hop).

The consumed link bandwidth BUT (l, m) obtained by Equation 6 above is broadcasted periodically or when there is a change in value. Then, the bandwidth B _consumed (k) _consumed at the neighbor node k of node l is calculated by Equation 7 below.

Meanwhile, the available bandwidth B _available (k) at the node k is calculated by Equation 8 below using the value of B _consumed (k) obtained through Equation 7 above.

Here, B _available (k) is an available bandwidth considering only the node itself, and in order to consider neighboring neighboring nodes, the minimum bandwidth B _min (k) should be calculated and used by Equation 9 below. do.

Here, the minimum bandwidth B _min (k) means the minimum value among the available bandwidths of neighboring neighboring nodes transmitting or receiving.

On the other hand, to reduce the routing protocol overhead, it is necessary bandwidth value when the frame loss probability is assumed to be 0. rawB _req (i, j) = B _{req, (l, m)} (i, j) | _{Calculate PDATA, (l, m) = 0} .

Using the available bandwidth B _available (k) and minimum bandwidth B _min (k) calculated as described above and the bandwidth B _{req, (l, m)} (i, j) required by the new traffic flow, the following table As in 1, the routing request is controlled according to the hop distance between the current node and the source node and whether the current node is the destination node or not.

 Here, k is indicated by the current node, k-1 by the previous node of the current node, k-2 by 2 hops before the current node, and k-3 by 3 hops before the current node.

On the other hand, the path setting method in a wireless ad hoc network according to an embodiment of the present invention may also be implemented as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored.

For example, the computer-readable recording medium may be a ROM, a RAM, a CD-ROM, a magnetic tape, a hard disk, a floppy disk, a removable storage device, a nonvolatile memory (Flash memory). Optical data storage, and the like, and also implemented in the form of a carrier wave (eg, transmission over the Internet).

The computer readable recording medium can also be distributed over computer systems connected over a computer network so that the computer readable code is stored and executed in a distributed fashion.

Although a preferred embodiment of a method for establishing a route in a wireless ad hoc network according to the present invention has been described above, the present invention is not limited thereto, but the scope of the claims and the detailed description of the invention and the accompanying drawings are various. It is possible to carry out the transformation to this also belongs to the present invention.

1 is a flowchart illustrating a path setting method in a wireless ad hoc network according to an embodiment of the present invention.

Claims (15)

What is claimed is: 1. A routing method for transmitting traffic between a source node and a destination node in a wireless ad-hoc network. (a) the source node broadcasting a route request (RREQ) message toward the destination node; (b) calculating, by neighbor nodes receiving the broadcast routing request message, an available bandwidth, a minimum bandwidth, and a required bandwidth value of new traffic; (c) determining whether each neighboring node satisfies a preset sufficient bandwidth condition according to the hop distance from the source node and the destination node using the calculated respective bandwidth values; (d) if the sufficient bandwidth condition is satisfied as a result of the determination in step (c), broadcasting the route establishment request message to the next neighbor nodes; And (e) repeating the steps (b) to (d), and when the route request message is transmitted to the corresponding destination node, the destination node transmits a route reply response (RREP) message to the source node. Route setting method in a wireless ad hoc network comprising. According to claim 1, wherein the determination result in step (c), And discarding the received routing request message when the neighboring nodes do not satisfy the sufficient bandwidth condition. The method of claim 1, And the routing request message includes parameter values necessary to check the sufficient bandwidth condition. The method of claim 1, The required bandwidth of the new traffic is the bandwidth required when traffic due to the data flow between the source node i and the destination node j is transmitted between one hop node (nodes l and m) {B _{req, (l, m). )} (i, j)}, and is calculated by the following equation (10).

Herein, R (i, j) is a packet generation time interval of traffic, B _channel is a transmission rate of an IEEE 802.11 air interface, and T _{data, (l, m)} (i, j) is required to transmit data. It's time. The method of claim 4, wherein The T _{data, (l, m)} (i, j) is a case of considering the IEEE 802.11 MAC frame loss probability (P _{DATA, (l, m)} ) between 1-hop nodes (nodes l and m) and RTS (Request to When not using the Send / Clear to Send (CTS) mechanism is calculated by the following equation (11).

Here, h is a limit value of retransmission when MAC frame loss is defined in the IEEE 802.11 standard, and T ' _{c, DATA, (l, m)} is the time spent when a collision occurs when transmitting the MAC frame , T ' _{s, DATA, (l, m)} is the time spent when the MAC frame is successfully transmitted, the T _CW (k) is the backoff according to the number k of attempts to retransmit the MAC frame It's time. The method of claim 5, wherein The T ' _{c, DATA, (l, m)} is calculated by the following equation (12 ₎ .

Here, T _difs and T _ACKTimeout are DIFS values defined in the IEEE 802.11 standard and timeout values of ACK frames. The method of claim 5, wherein The T _{'s, DATA, (l, m)} is calculated by the following equation (13 ₎ .

Where H is the length of a header, L (i, j) is the length of a packet, T _ack is the time spent transmitting an ACK frame of an IEEE 802.11 MAC, and T _sifs is an IEEE 802.11 standard. SIFS time. The method of claim 5, wherein The T _CW (k) is calculated by the following equation (14).

Here, CW _min and CW _max are the minimum and maximum values of the backoff time in the IEEE 802.11 standard, respectively, and the T _SlotTime is the slot time in the IEEE 802.11 standard. The method of claim 1, The available bandwidth is the available bandwidth (B _available (k)) at node k, and is calculated by Equation 15 below.

Here, the B _channel is the transmission rate of the IEEE 802.11 air interface, and B _consumed (k) is the bandwidth consumed at the neighbor node k of the node l. The method of claim 9, The B _consumed (k) is calculated by the following equation (16).

Here, the BUT (l, m) is the bandwidth consumed in the link connecting the two nodes l and m. The method of claim 10, The BUT (l, m) is calculated by Equation 17 below.

Here, N (l) means one-hop peripheral node of node l, and Next (i, j) is the next node of the routing table at node l for traffic flow in which source node is i and destination node is j. (Next Hop). The method of claim 11, The BUT (l, m) is a method for routing in a wireless ad hoc network, characterized in that the transmission periodically or when the value changes. The method of claim 1, The minimum bandwidth is a bandwidth B _min (k) at node k, which represents a minimum value among available bandwidths of neighboring nodes transmitting or receiving, and is calculated by Equation 18 below. How to route on the network.

Here, B _available (k) is available bandwidth at node k, and the BUT (i, j) is the bandwidth consumed in the link connecting two nodes i and j. The method of claim 1, The sufficient bandwidth condition is represented by Table 2 below.

Here, k is the current node, k-1 is the previous node of the current node, k-2 is 2 hops before the current node, and k-3 is 3 hops before the current node. A non-transitory computer-readable recording medium having recorded thereon a program capable of executing the method of claim 1.

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