KR100932556B1 - Routing path setting method for vehicle-to-vehicle communication and terminal device performing the same - Google Patents

Abstract

The present invention relates to a routing path setting method for vehicle-to-vehicle communication and a terminal apparatus performing the same.

According to the present invention, the route duration for each routing path may be determined using vehicle operation information of a neighboring node and vehicle operation information of an arbitrary node extracted from each of one or more routing path establishment requests for establishing a routing path between a source node and a destination node. Predict. The data transmission is performed between the source node and the destination node through a routing path having a path duration having a relatively large value selected from among the estimated path durations for each routing path.

Thus, by predicting the mobility of the vehicle, it establishes an optimal routing path composed of nodes having similar directions and speeds within the communication range, thereby reducing unnecessary routing re-scanning procedures, and reducing movement patterns such as source and destination nodes. A branch can establish a routing path composed of nodes.

Ad-hoc On-demand Distance Vector (AODV), Route Request (RREQ), Route Reply (RREP)

Description

Method for establishing routing path for vehicle-to-vehicle communication and terminal device performing the same

The present invention relates to a routing path setting method for vehicle-to-vehicle communication and a terminal apparatus performing the same. In particular, the present invention relates to a method for establishing a routing path using the AODV routing protocol in an inter-vehicle multi-hop communication, and a terminal apparatus for performing the same.

The present invention is derived from a study conducted as part of the IT source technology development project of the Ministry of Information and Communication and the Ministry of Information and Communication Research and Development (Task Management No .: 2007-F-039-01, Task Name: VMC Technology Development).

Vehicle-to-vehicle communication technology is being actively researched in the field of the vehicle's safe driving support system. Vehicle-to-vehicle communication technology is emerging as a technology that will be actively used in next generation traffic safety and next generation intelligent development, along with the rapid development of intelligent transportation systems (ITS), telematics market.

Multi-hop routing technology in vehicle-to-vehicle communication has a similar part to the communication pattern of the existing mobile ad-hoc network (MANET). Therefore, efforts are being made to apply the routing protocols used in MANET to the inter-vehicle communication environment. MANET has the characteristic of constructing a network by itself, and to do this, it is necessary to be able to construct a route by itself.

Ad-hoc On-demand Distance Vector (hereinafter, referred to as 'AODV') protocol, which is widely used in the conventional MANET, is a typical routing protocol of the on-demand method that well reflects the characteristics of the ad hoc network.

The AODV protocol has the disadvantage of increasing the overall network utilization because it needs to exchange periodic messages such as Hello messages.

In addition, the AODV protocol has a topology that changes over time because the inherent problem of multi-hop networks is that the nodes are flexible and can lead to disconnection between two nodes relaying traffic for a particular connection. However, the conventional AODV protocol does not reflect such a rapid change in topology, and thus, a frequently set routing path is not an optimal path, which causes a frequent routing rescanning process.

An object of the present invention is to provide a method for searching a robust routing path that lasts as long as possible through the prediction of the mobility of the vehicle so as to minimize the re-discovery of unnecessary routing paths and a terminal device performing the same.

Routing routing method that is a feature of the present invention for achieving the technical problem of the present invention,

A method of establishing a routing path in a multi-hop network composed of a plurality of nodes for inter-vehicle communication, the method comprising: a source node including a vehicle driving information of the source node to broadcast a route setting request to a destination node for data transmission; ; Receiving a route setting response including a route duration estimated from the destination node using the vehicle driving information; And transmitting data to the destination node through a routing path corresponding to a path duration extracted from the response to the path establishment request.

Terminal device which is another feature of the present invention for achieving the technical problem of the present invention,

A terminal device mounted on the node to establish a routing path in a multi-hop network including a plurality of nodes for inter-vehicle communication, the terminal device including the vehicle driving information of the terminal device to broadcast a route setting request for data transmission. A routing engine configured to receive a route setting response including a predicted route duration using the vehicle driving information; And a forwarding engine configured to transmit data through a routing path corresponding to a path duration extracted from the response to the path establishment request.

As described above, according to the present invention, since the routing path is set to nodes having similar directions and speeds within the communication range by estimating the mobility of the vehicle in the fast moving network, the unnecessary path re-exploration is maximized by maximizing the survival time of the routing path. The procedure can be reduced.

As a result, the overall performance of AODV can be improved and ultimately, it is expected to support the efficient operation of the inter-vehicle communication network and the implementation of application services using various inter-vehicle communication.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “module”, etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software, or a combination of hardware and software.

Now, a routing path setting method for inter-vehicle communication and a terminal device performing the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a terminal device for setting a routing path in an inter-vehicle multi-hop communication according to an embodiment of the present invention.

As shown in FIG. 1, a terminal device 100 is mounted on a moving vehicle, respectively. At this time, it is assumed that the vehicle equipped with the terminal device 100 is a communication node in the inter-vehicle network.

That is, in a multi-hop network composed of a plurality of vehicles and each vehicle composed of one node, communication between vehicles is performed through an Ad-hoc On-demand Distance Vector (hereinafter referred to as 'AODV'). do.

In the AODV protocol, a routing path for transmitting a data packet is exchanged between vehicles by exchanging a route request (RREQ) message and a route reply (RREP) message. Set it.

Here, the RREQ message is a message type used by the source node to search for a path to the destination node, that is, to generate a path, and the RREP message is a message type used to respond to the RREQ message.

In this case, the AODV to which the algorithm of the present invention is applied is referred to as a mobility prediction based AODV (MP-AODV) routing protocol.

On the other hand, the configuration of the terminal device 100 mounted in each vehicle is the GPS module 110, GPS location tracking unit 120, vehicle operation information management module 130, routing engine 140, routing table storage unit ( 150, packet forwarding engine 160, and wireless network card 170.

The GPS module 110 receives radio waves transmitted by three satellites out of 24 GPS satellites managed by the US DoD.

The GPS location tracking unit 120 detects the location of the latitude and longitude of the vehicle using the signal received by the GPS module 110.

The vehicle driving information management module 130 grasps and manages vehicle driving information including position, speed, and direction information of the vehicle.

The routing engine 140 estimates the link duration between the vehicles and the routing path duration between the source node and the destination node. In this case, the link duration and the routing path duration are predicted by using the vehicle driving information of the own vehicle obtained from the vehicle driving information management module 130 and the vehicle driving information of the adjacent vehicle included in the RREQ message received from the neighboring node. .

Here, the link duration and routing path duration are defined as follows.

First, the link duration is defined as the maximum time that communication between adjacent mobile nodes i and j can be maintained.

Link duration is an important factor in determining link robustness and is an important performance indicator when establishing a path in the MP-AODV protocol.

The link duration LD may be expressed by the following equation.

LD (i, j, k) = t2-t1

if ∀t t1 ≤ t ≤ t2, ε> 0:

X (i, j, t) = 1 and X (i, j, t1-ε) = 0 and X (i, j, t2 + ε) = 0

Otherwise, LD (i, j, t1) = 0

Here, if there is a communication link between mobile nodes i and j, then set X (i, j, t) = 1. Conversely, if there is no communication link, then X (i, j, t) = 0. Therefore, when the mobile nodes i and j have a time interval t2-t1 within the transmission range, the link duration from time t1 is represented by LD (i, j, t1).

Next, the routing path duration is defined as the maximum time that a communication path is maintained between node i and node j in a multi-hop network.

Paths connected by links between nodes are broken when one link is broken. Therefore, the smallest value of the link durations is the path duration.

The path duration PD may be expressed by the following equation.

PD (n1, nk, t1) = Min LD (n _z , n _{z +1} , t1)

1≤Z≤k-1

At time t1, the path P = {n1, n2, ..., nk,} with k nodes has k-1 links and the minimum LD value of the link determines the PD value. At t1-ε and t2 + ε, the time when the link is disconnected, the path does not exist.

In this case, although not shown in the figure, the routing engine 140 includes a configuration divided into a first routing engine unit for processing a route request message and a second routing engine unit for processing a route response message according to its function. The first routing engine unit and the second routing engine unit perform functions of each of the source node, the intermediate node, and the destination node. The detailed operation thereof will be described in more detail with reference to FIGS. 4 to 6 below.

The routing table storage unit 150 stores a routing table in which the path duration predicted by the routing engine 140 is stored and updated as the multi-path survival time.

The packet forwarding engine 160 forwards the packet to the selected optimal node by referring to the routing table stored in the routing table storage 150.

The wireless network card 170 receives the packet forwarded by the packet forwarding engine 160, transmits the packet to the neighbor node, receives the packet received from the neighbor node, and outputs the packet received from the neighbor node to the routing engine 140.

2A is a configuration example of an RREQ message format according to an embodiment of the present invention, and FIG. 2B is a configuration example of an RREP message format according to an embodiment of the present invention.

As shown in Figures 2a and 2b, the RREQ message and RREP message of the MP-AODV routing protocol has been modified using the extension message type of the existing AODV protocol, except for the extension portion is the same as the existing AODV protocol message.

According to FIG. 2A, the extended portion 200 of the RREQ message includes an extension type 201, a length 203, and vehicle driving information 205, 207, 209, 211, and 213.

The vehicle driving information 205, 207, 209, 211, and 213 may specifically include a path duration 205, a node velocity 207, a direction 209, and a latitude. (GPS position) 211 and Longitude (GPS Position) 213 information is included.

The vehicle driving information 205, 207, 209, 211, 213 is used to calculate link duration and path duration between nodes as the message is delivered.

This RREQ message is delivered to the neighbor node through broadcasting, and the link duration is obtained according to the following equation. Here, the communication radius is assumed to be a constant value.

If adjacent nodes i and j are within the transmission range (r = 2/3 * communication radius), the coordinates (xi, yi) of node i and the coordinates (xj, yj) of node j can be obtained through message exchange. In addition, the speeds of the two nodes vi, vj, and the directions θi and θj of the two nodes can be known.

a = vi * cosθi-vj * cosθj

b = xi-xj

c = vi * sinθi-vj * sinθj

d = yi-yj

을 획득할 수 있다.Using the information obtained using Equation 3, Equation 4, Equation 5, and Equation 6, the link durations of the two nodes are calculated as follows.

Can be obtained.

[Equation 7]

According to FIG. 2B, the RREP message is a response message for establishing a path when the RREQ message arrives at the destination node.

The extension portion 300 of the RREP message includes an extension type 301, a length 303, and a path duration 305.

Here, the path duration 305 is a finally calculated path duration 305 that informs the source node of the routing path.

3 is a configuration example of a routing table according to an embodiment of the present invention, and is stored in the routing table storage unit 150 of FIG. 1.

As shown in FIG. 3, the routing table of the MP-AODV protocol maintains multiple routing paths unlike the routing table of the existing AODV protocol.

The extended portion 400 of the routing table consists of one or more routing paths and survival times for each of the routing paths.

The extended portion 400 of the routing table includes a routing list 401 along multiple routing paths.

The routing list 401 includes a hop count 403, a next hop 405, and a life time 407 for each path.

The lifetime 407 of each path is set to the path duration. The path duration is selected by comparing the path duration in the RREQ message received by the node with the link duration with the previous node that forwarded the RREQ message, and the selected value is updated with the path duration.

Now, a process of setting a routing path of the MP-AODV protocol based on the configuration of the terminal device 100 described above will be described.

First, FIG. 4 is a flowchart illustrating a method of generating an RREQ message according to an embodiment of the present invention, and illustrates a procedure of setting a routing path for a source node to transmit data to a destination node.

As shown in FIG. 4, when a data transmission request is generated (S101), it is determined whether a routing path to a destination node exists (S103).

As a result of the determination in step S103, if a routing path exists, it is checked whether the path duration of the routing path has expired (S105).

If the path duration has not expired as a result of the check in step S105, the data packet in which the transfer request has occurred in step S101 is transmitted through the routing path confirmed in step S103 (S107).

If the determination result in step S103 does not exist or the path duration of the routing path expires as a result of the check in step S105, an RREQ message is generated (S109) to start the routing path search process.

The RREQ message generated in step S109 includes the location, speed, direction, and path duration information of the source node (S111). At this time, the initial value of the path duration information is set to infinity (∞).

The generated RREQ message is broadcast to the neighbor node (S113).

Next, FIG. 5 is a flowchart illustrating a RREQ message delivery method according to an embodiment of the present invention, and illustrates a procedure in which a node receiving an RREQ message configures a routing table and forwards an RREQ message.

As shown in FIG. 5, when a node receives an RREQ message from an adjacent node (S201), a path duration is calculated (S203). At this time, while the conventional AODV protocol deletes all the duplicated RREQ messages, the MP-AODV protocol of the present invention calculates the path duration by receiving the same RREQ message received on the new path.

The path duration calculated in step S203 is stored as a survival time in the routing table (S205).

At this time, it is determined whether the node that has received the RREQ message in step S201 is the destination node (S207).

If the node that has received the RREQ message in step S207 is not a destination node, that is, an intermediate node, the extended portion (200 of FIG. 2A) of the received RREQ message includes its vehicle driving information, that is, location, speed, direction, and route duration. After updating (S209) and forwarding (S211).

If the node receiving the RREQ message in step S207 is the destination node, it is determined whether the RREQ message received in step S201 is the first received RREQ message (S213).

As a result of the determination in step S213, in the case of the first received RREQ message, an RREP message including the last calculated path duration is generated for the first RREQ (S201) received (S215), and then the uni- verse until the next hop (Hop) of the routing path. Cast (S217).

As a result of the determination in step S213, if it is not the first received RREQ message, the source node waits until the data packet is transmitted (S219).

Then, the RREQ message received in another path is stored in the routing table until the first data packet arrives (S221).

When the first data packet is received from the source node (S223), a routing path having a maximum path duration, that is, a survival time, is selected from the routing paths recorded in the routing table (S225).

The updated RREP message is again sent through the routing path selected in step S225 (S227).

In this way, the routing path having the maximum path duration is established through one RREQ message.

Next, FIG. 6 is a flowchart illustrating a method of processing an RREP message according to an embodiment of the present invention, and illustrates a procedure of configuring a routing table and processing an RREP message when a node receives an RREP message.

As shown in FIG. 6, all nodes that have received the RREP message (S301) update the path duration recorded in the message to the survival time of their routing table (S303).

At this time, the node receiving the RREP message determines whether it is a source node (S305).

As a result of the determination in step S305, in the case of the source node, data transmission starts (S307).

As a result of the determination in step S305, when the node is not the source node, that is, the intermediate node, the node having the maximum path duration, that is, the survival time, is selected as a forward node among the next hops from the routing table to the source node (S309).

The RREP message is unicasted to the forward node selected in step S309 (S311).

As such, when the mobility path of the vehicle is predicted to select nodes having similar directions and speeds within the communication range to set the routing path, the routing path is composed of nodes having the same movement pattern as the source node and the destination node. Therefore, by maximizing the survival time of the routing path, unnecessary path rescanning procedure can be reduced, and a routing path suitable for a communication pattern requiring group communication such as clustering can be set.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a block diagram of an on-vehicle terminal device for setting a routing path in an inter-vehicle multi-hop communication according to an embodiment of the present invention.

2A is a configuration example of an RREQ message format according to an embodiment of the present invention, and FIG. 2B is a configuration example of an RREP message format according to an embodiment of the present invention.

3 is a configuration example of a routing table according to an embodiment of the present invention.

4 is a flowchart illustrating a method of generating an RREQ message according to an embodiment of the present invention.

5 is a flowchart illustrating a RREQ message delivery method according to an embodiment of the present invention.

6 is a flowchart illustrating a method of processing an RREP message according to an embodiment of the present invention.

Claims (11)

A method for establishing a routing path in a multi-hop network composed of a plurality of nodes for inter-vehicle communication, A source node including its own vehicle driving information to broadcast a route setting request to a destination node for data transmission; Receiving a route setting response including a route duration estimated from the destination node using the vehicle driving information; And Transmitting data to the destination node through a routing path corresponding to a path duration extracted from the path setting response; Routing path setting method comprising a. The method of claim 1, The broadcasting step, Determining whether to generate the route setting request according to whether a path duration of a routing path for transmitting data to the destination node expires; And When the generation of the route setting request is determined, generating the route setting request by including vehicle driving information including the location, speed, and direction information of the source node and an initialization route duration; Routing path setting method comprising a. The method according to claim 1 or 2, Between the broadcasting and receiving; Estimating a link duration with a node that has transmitted a routing request using node own vehicle driving information of the node receiving the routing request by the node receiving the routing request; Comparing the link duration with the path duration included in the path establishment request and updating a small value with a new path duration Routing path setting method further comprising. The method of claim 3, The updating step, If the routing request is received through different nodes, the routing path establishment method of generating a multi-path consisting of the different nodes and setting the survival time of the multi-path to the new path duration. The method of claim 4, wherein After the updating step, If the node receiving the route request is the destination node, including the updated new route duration in a route setup response and transmitting it to the source node; Routing path setting method further comprising. The method of claim 5, After transmitting to the source node, Confirming a survival time of the multipath when data is first received from the source node; Selecting a path having the maximum survival time and selecting a next hop included in the path as a forward node; And Resending the routing response to the forward node by setting the survival time of the selected path to a path duration time; Routing path setting method further comprising. The method of claim 6, Between the broadcasting and receiving; Updating, by the node receiving the routing response, the path duration included in the routing response to the survival time of the routing path to the source node; And If the next hop of the routing path is not a source node, selecting a routing path having a maximum survival time of the routing path, and selecting a next hop included in the routing path as a forward node to forward the routing response; Routing path setting method further comprising. In a multi-hop network consisting of a plurality of nodes for inter-vehicle communication, the terminal device mounted on the node to establish a routing path, A routing engine including a vehicle driving information of the terminal device to broadcast a route setting request for data transmission and receiving a route setting response including a predicted route duration using the vehicle driving information; And A forwarding engine that transmits data through a routing path corresponding to a path duration extracted from the routing response. Terminal device comprising a. The method of claim 8, The routing engine, A routing table storage unit for storing a routing table consisting of a multipath consisting of different nodes from a source node to a destination node and a path survival time of the multipath; When the route setting request is received, the link duration time between the terminal apparatus of the adjacent vehicle transmitting the route setting request predicted using the vehicle driving information of the terminal apparatus and the route duration time included in the route setting request. Comparing the first routing engine module to update the small value with the new path duration; And When the terminal device is a destination node, the updated new path duration is included in a path setting response and transmitted to the source node. When data is first received from the source node, the path table is searched for by searching the routing table. A second routing engine module that selects a path that is maximum and retransmits the routing response to the forward node with the next hop included in the path as a forward node Terminal device comprising a. The method of claim 9, The first routing engine module, A terminal that searches for the routing table and broadcasts the route setting request by including its own vehicle driving information including the location, speed, and direction information and an initialization path duration through a routing path whose selected path survival time has not expired. Device. The method of claim 10, The second routing engine module, When the routing response is received, the routing response is updated by updating the path duration included in the routing response to the routing table and selecting a next hop included in the routing path having the maximum path survival time as a forward node. Terminal device to pass.

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