KR101262326B1 - Message transmission apparatus and method for transmitting message thereof - Google Patents

Abstract

The present invention relates to a method for transmitting a vehicle message of a transmitting node. In the message transmission method of the transmitting node of the present invention, the method comprises: broadcasting an initial message for transmitting a message, the lowest value of the signal-to-noise ratio for each of the received signals from the neighboring nodes compared to the lowest value of the signal-to-noise ratio of the other neighboring nodes; Selecting at least one neighbor node among the relatively high neighbor nodes as a relay node, and receiving a message having a transmission pattern included in the initial message together with the at least one relay node selected as the selected target node based on the received signals. Transmitting.

Description

The transport node and its message transmission method {MESSAGE TRANSMISSION APPARATUS AND METHOD FOR TRANSMITTING MESSAGE THEREOF}

The present invention relates to a communication network, and more particularly, to a transmitting node and a method for transmitting a message thereof in a vehicle ad-hoc communication network.

In one example of a communication network, a vehicle message used in a vehicle communication network includes information for safe driving of a vehicle.

Vehicle messages used in a vehicle communication network mostly contain information for safe driving of a vehicle. Therefore, the vehicle message needs high reliability in accordance with the transmission.

Current vehicle messages are transmitted between vehicles via a broadcast scheme. Broadcasting vehicle messages are less reliable in message transmission due to wireless fading. To this end, each vehicle can improve the reliability of message transmission by retransmitting vehicle messages. However, there is a limit in solving the attenuation of the transmission signal due to radio fading by retransmission of the vehicle message. Therefore, there is a problem that the time required for retransmission of the vehicle message for securing a certain level or more of reliability increases.

It is an object of the present invention to provide a transmission node and a message transmission method thereof which improve the reliability of vehicle message transmission.

In the message transmission method of the transmitting node of the present invention, the method comprises: broadcasting an initial message for transmitting a message, the lowest value of the signal-to-noise ratio for each of the received signals from the neighboring nodes compared to the lowest value of the signal-to-noise ratio of the other neighboring nodes; Selecting at least one neighbor node among relatively high neighbor nodes as a relay node, and transmitting a transmission pattern included in the initial message together with the selected at least one relay node to a selected target node based on the received signals; Sending a message having the same.

In this embodiment, the method may further include selecting the number of the target nodes based on a received signal probability for each of the received signals.

In this embodiment, selecting the target node includes selecting a neighbor node as a target node whose signal-to-noise ratio is relatively smaller than other neighbor nodes.

In this embodiment, the message is a message for notifying occurrence of an emergency situation occurring at the transmitting node.

In this embodiment, the step of selecting at least one relay node, when receiving pilot signals from all the selected relay nodes, completing the selection of the relay node through the transmission of a pilot signal corresponding to the pilot signals Steps.

In this embodiment, selecting the at least one relay node comprises broadcasting the initial message if no pilot signals are received from all selected relay nodes.

The transmitting node of the present invention generates a node information collecting unit that collects neighbor node information from received signals of neighbor nodes, a message for transmission to the neighbor nodes, and a transmission error of the message using the neighbor node information. A message processing unit for selecting a potential target node and a relay node for cooperative transmission of the message, and transmission and reception for receiving the received signals from the neighboring nodes and cooperatively transmitting the message to the target node together with the relay node. And the message processing unit selects at least one neighboring node among the neighboring nodes of which the lowest value of the signal-to-noise ratio for each of the received signals is higher than the lowest value of the signal-to-noise ratio of other neighboring nodes as the relay node. do.

In this embodiment, the message processor selects a target node based on a signal-to-noise ratio of each of the received messages and a reception error probability of each of the received messages.

In this embodiment, the message processing unit includes the step of setting the number of the target node based on the reception error probability.

In this embodiment, the message processing unit includes selecting a neighboring node having a relatively small signal-to-noise ratio compared to other neighboring nodes as a target node.

In this embodiment, when the transceiver receives pilot signals from all the selected relay nodes, the transceiver transmits a pilot signal corresponding to the pilot signal.

In this embodiment, if the transceiver does not receive the pilot signal from all the selected relay nodes, broadcasts the initial message.

In this embodiment, the transceiver unit encodes the messages by a space-time encoding scheme.

In this embodiment, the transceiver repeatedly transmits a message with the relay node a predetermined number of times over a predetermined time interval.

In this embodiment, the transmitting node further comprises a sensor unit for detecting an emergency situation of the vehicle.

In this embodiment, the message generator generates a message for notifying the emergency situation according to the emergency situation detection.

According to the present invention, the transmitting node can improve the reliability according to the vehicle message transmission by allowing the relay node to obtain diversity at the target node through cooperative transmission of the vehicle message.

1 illustrates a vehicle ad-hoc communication network in accordance with the present invention;
2 is a diagram illustrating a transmission node according to the present invention;
3 is a view showing the node information collecting unit shown in FIG.
4 is a diagram illustrating a vehicle message transmission operation according to the present invention;
5 is a flowchart illustrating a vehicle message transmission operation of a transmitting node according to an embodiment of the present invention;
6 illustrates a signal-to-noise ratio of neighboring nodes for selecting a relay node for relaying a vehicle message according to the present invention; and
7 illustrates a target area of a vehicle for transmitting a vehicle message according to an exemplary embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish it, will be described with reference to the embodiments described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. The embodiments are provided so that those skilled in the art can easily carry out the technical idea of the present invention to those skilled in the art.

In the drawings, embodiments of the present invention are not limited to the specific forms shown and are exaggerated for clarity. In addition, parts denoted by the same reference numerals throughout the specification represent the same components.

The present invention relates to a communication network, for example, to a transmitting node having a high reliability according to message transmission in a vehicle ad-hoc communication network and a method for transmitting the message thereof. As an example, description will be made based on vehicle messages transmitted and received in a vehicle ad-hoc communication network. However, the vehicle message transmission method proposed in the present invention can be used for message transmission in other ad-hoc communication networks.

Meanwhile, the communication scheme for transmitting and receiving a vehicle message proposed in the present invention may use, for example, a communication scheme of IEEE 802.11. In addition, the IEEE 802.11 method is described as an example and may communicate using another communication method.

1 illustrates a vehicle ad-hoc communication network in accordance with the present invention.

Referring to FIG. 1, a vehicle ad-hoc communication network includes a target node 10, a relay node 20, and a transmitting node 30. Here, each of the nodes 10, 20, 30 may be regarded as one vehicle.

The target node 10 is a node at risk of not receiving a vehicle message (or message). The vehicle message includes various information for safe driving between the vehicles, for example, vehicle identifier information, vehicle speed information, and emergency occurrence information. Here, the emergency situation includes a crash situation of the vehicle, a crash expectation situation of the vehicle, a breakdown situation of the vehicle, an emergency stop situation of the vehicle, and the like.

The relay node 20 is a node for relaying a vehicle message transmitted from the transmitting node 30 to the target node 10. The relay node 20 is selected, for example, by the transmitting node 30 according to a contention-based distributed algorithm for cooperative transmission of vehicle messages with the transmitting node 30.

The transmitting node 30 is a node for transmitting the vehicle message. The transmitting node 30 may generate a vehicle message.

Meanwhile, the vehicle message transmission method proposed in the present invention includes an initial broadcasting operation, a relay node selection operation, and a cooperative transmission operation.

In an initial broadcasting operation, the transmitting node 30 broadcasts an initial vehicle message, including a vehicle message for repeated transmission. In this case, the transmitting node 30 may select the number of target nodes 10 by using beacon signals received from neighboring vehicles. The beacon signal is a signal that is periodically transmitted and received between neighboring vehicles. The transmission node 30 selects a neighboring vehicle as a target node 10 whose signal-to-noise ratio (SNR) is relatively low compared to the signal-to-noise ratios of other neighboring nodes.

In the relay node selection operation, the transmitting node 30 selects relay nodes for cooperative transmission of the vehicle message. The relay node 20 is selected by the transmitting node 30 among the target node 10 and neighboring nodes that can guarantee the best channel condition. To this end, the transmitting node 30 selects the relay node 20 using beacon signals. The transmission node 30 selects the neighboring node as the relay node 20 whose lowest value of the signal-to-noise ratio obtained through the beacon signal is relatively higher than the lowest value of the signal-to-noise ratio of other neighboring nodes.

In the cooperative transmission operation, the transmitting node 30 transmits a vehicle message at a preset time period. In this case, the relay node 20 transmits a vehicle message together with the transmitting node 30 in a preset time period. Through this, the transmitting node 30 transmits the same vehicle message to the target node 10 in cooperation with the relay node 20 in a preset time period.

The vehicle message cooperatively transmitted by the transmitting node 30 and the relay node 20 is included in the initial vehicle message.

For convenience of explanation, the description is made based on one target node 10 and one relay node 20. However, two or more target nodes 10 and relay nodes 20 may be used for vehicle message transmission.

As a result, in the present invention, the transmitting node 30 cooperates with the relay node 20 to transmit the vehicle message to the target node 10. This reduces the probability of not receiving a vehicle message by acquiring a diversity gain at the target node 10. Therefore, the transmission node 30 proposed in the present invention can improve the reliability according to vehicle message transmission.

2 is a diagram illustrating a transmission node according to the present invention.

Referring to FIG. 2, the transmitting node 30 includes a transceiver 110, a node information collecting unit 120, a sensor unit 130, and a message generating unit 140. Here, the transmitting node 30 may be one vehicle and communicates with neighboring nodes (ie, neighboring vehicles) located in the vicinity.

The transceiver 110 includes an antenna and transmits and receives a vehicle message with neighboring nodes located in a target area. The target area is an area centered on the transmission node 30 and is a reception area of the vehicle message transmitted from the transmission node 30. The transceiver 110 outputs the vehicle message received through the antenna to the node information collector 120 and transmits the vehicle message from the message generator 140 through the antenna.

The node information collecting unit 120 collects information of a neighbor node (neighbor vehicle) through a vehicle message (for example, a beacon signal) received through the transmitting and receiving unit 110. To this end, the node information collector 120 may measure the signal strength of the beacon signal. Here, the signal strength is information representing a channel state, and includes, for example, a signal to noise ratio (SNR). In addition, the node information collector 120 may measure a signal reception probability of the beacon signal. Here, the signal reception probability is information indicating a reception success probability of the beacon signal, and for example, includes a beacon reception ratio (BRR).

The node information collector 120 may collect neighbor node information such as signal strength (SNR) and signal reception probability (BRR) for each of the neighbor nodes. The node information collecting unit 120 provides neighbor node information to the message generating unit 140.

The sensor unit 130 detects an emergency situation. The sensor unit 130 may include various sensors such as a collision sensor for detecting a collision, an image sensor for photographing front, rear, left and right images, a speed sensor for measuring the speed of the vehicle, and a position sensor for measuring the position of the vehicle. When the emergency situation is detected through the sensor, the sensor unit 130 outputs the detected emergency situation occurrence information to the message generator 140.

)를 하기의 수학식 1을 이용하여 계산할 수 있다.The message generator 140 may select the number of target nodes based on neighbor node information, for example, a signal reception probability. Message generation unit 140 is the number of target nodes (

) Can be calculated using Equation 1 below.

는 타겟 영역에 존재하는 노드(일예로, 차량)들의 개수이고, ABRR(Average Beacon Reception Rate)은 타겟 영역에 존재하는 차량들에 대한 신호 수신 확률의 평균이다. 메시지 생성부(140)는 ABBR(평균 신호 수신 확률)을 일예로, 하기의 수학식 2를 통해 계산할 수 있다.here,

Is the number of nodes (eg, vehicles) present in the target area, and Average Beacon Reception Rate (ABRR) is an average of signal reception probabilities for vehicles existing in the target area. The message generator 140 may calculate an ABBR (average signal reception probability) as an example, through Equation 2 below.

개의 타겟 노드를 선택할 수 있다.Meanwhile, the message generator 140 sequentially selects a channel state, for example, a vehicle having the smallest signal-to-noise ratio, as a target node through received signals received from neighboring nodes. The message generator 140 starts from the vehicle having the smallest signal to noise ratio.

Target nodes can be selected.

The message generator 140 generates a vehicle message. The message generator 140 may notify an emergency situation generated in the vehicle through the vehicle message. In this case, the message generator 140 may generate the vehicle message based on the emergency situation information received from the sensor unit 130.

) 내에서 k번 반복 전송된다.The message generator 140 may generate an initial vehicle message including a transmission pattern for repetitive transmission of the target node information and the vehicle message, that is, the vehicle message. Where the vehicle message is the lifetime of the vehicle message (

Repeats k times within

The message generator 140 divides the entire time interval for transmitting the vehicle message into a plurality of unit time intervals L. FIG. One unit time interval L includes all of an initial broadcasting operation time, a relay node selection time, and a cooperative transmission operation execution time.

)을 분할된 단위 시간 구간(L)으로 나누어 최대 반복 전송 가능한 시간 구간의 개수(

)를 계산할 수 있다. 메시지 생성부(140)는 차량 메시지 수명 시간(

) 내에서 k번 반복 전송되도록 차량 메시지를 송수신부(110)로 출력한다. 메시지 생성부(140)는 릴레이 노드와 함께 반복 시간 구간(P)마다 차량 메시지를 반복 전송한다. 반복 시간 구간(P)은 하기의 수학식 3으로 계산될 수 있다.Message generation unit 140 is a vehicle message life time (

) Is divided into divided unit time intervals (L) and the maximum number of repeatable transmission time intervals (

) Can be calculated. Message generation unit 140 is a vehicle message life time (

) And outputs the vehicle message to the transceiver 110 to be repeatedly transmitted k times within). The message generator 140 repeatedly transmits the vehicle message for each repetition time interval P together with the relay node. The repetition time interval P may be calculated by Equation 3 below.

The message generator 140 may generate a vehicle message including information on the number of repetitive transmissions (k), the repetition time interval (P), and the divided time interval (L). The message generator 140 outputs the vehicle message to the transceiver 110.

The message generator 140 may select a relay node for cooperative transmission of the vehicle message to the target node. The message generator 140 may use signal strength (eg, signal-to-noise ratio (SNR)) for relay node selection. The message generator 140 sequentially selects the relay node from the vehicle having the largest minimum signal strength for each of the neighboring vehicles. Through this, the message generator 140 may select a relay node having a good channel state for vehicle message cooperative transmission.

When the message generator 140 receives the pilot message from all the relay nodes selected according to the initial vehicle message transmission, the message generator 140 outputs a pilot signal for completing the relay node selection to the transceiver 110.

In addition, the message generator 140 generates a beacon signal and generates a beacon signal at regular intervals. The beacon signal includes, for example, vehicle identifier information for identifying a vehicle and a sequence number for calculating a reception success probability. In this case, the sequence number may consist of one of consecutive numbers. In addition, the beacon signal may include vehicle speed information indicating the speed of the vehicle and vehicle location information indicating the position of the vehicle. The message generator 140 outputs the beacon signal to the transceiver 110.

The transmission node 30 of the present invention sequentially selects the relay node from the vehicle having the best channel state based on the minimum value of the signal strength. The transmitting node 30 transmits a vehicle message with a relay node having a high diversity gain. Accordingly, the transmitting node 30 may transmit the vehicle message to the target node to have a higher diversity gain.

3 is a diagram illustrating a node information collecting unit illustrated in FIG. 2.

Referring to FIG. 3, the node information collecting unit 120 includes a signal strength measuring unit 121, a signal receiving probability measuring unit 122, and a neighbor node information managing unit 123.

The signal strength measuring unit 121 measures the signal strength (channel state). For example, the signal strength measuring unit 121 measures a signal-to-noise ratio using a received signal, for example, a beacon signal. The signal strength measuring unit 121 outputs the measured signal strength to the neighbor node information management unit 123.

The signal reception probability measuring unit 122 calculates a reception success probability of the beacon signal using the sequence number of the beacon signal. The signal reception probability measuring unit 122 may calculate the beacon reception probability by checking the number of beacon signals lost from a predetermined number of beacon signals. For example, when four beacon signals are not received among the ten beacon signals, the signal reception probability measuring unit 122 obtains a signal reception probability of 0.6 (assuming that all beacon signals are received as '1'). can do.

The neighbor node information manager 123 manages the signal strength and the beacon reception probability measured for each node through the neighbor node information table. The neighbor node information manager 123 may provide the signal strength and the beacon reception probability to the message generator 140.

4 is a diagram illustrating a vehicle message transmission operation according to the present invention.

Referring to FIG. 4, a first time slot 210 and a P time slot 250 are shown. The first time slot 210 includes a first section T1, a second section T2, and a third section T3.

을 1씩 증가시킨다.

은 초기 차량 메시지 전송을 시작할 때 '0'으로 초기화되고, 동일 차량 메시지 전송을 위해 반복 송신된 초기 차량 메시지의 브로드캐스팅 횟수(즉, 초기 차량 메시지 전송 횟수)를 나타낸다. 그러므로 초기 차량 메시지(또는 차량 메시지)는

을 포함할 수 있다.The first section T1 is an initial broadcasting section. The first section T1 is a section in which the transmitting node broadcasts an initial vehicle message. The initial vehicle message includes a list of identifiers of target nodes and a vehicle message (or transmission pattern of the vehicle message) repeatedly transmitted. Each time a transmitting node performs initial vehicle message broadcasting for the same vehicle message transmission,

Increase by 1.

Is initialized to '0' at the beginning of initial vehicle message transmission and indicates the number of broadcasts (ie, initial vehicle message transmission) of the initial vehicle message repeatedly transmitted for the same vehicle message transmission. Therefore, the initial vehicle message (or vehicle message)

. ≪ / RTI >

)을 릴레이 노드 선택을 위한 기준으로 이용할 수 있다. 신호 대 잡음비의 최소값(

)은 전송 노드가 제공할 수 있는 신호 품질의 최대값을 나타낸다.The second section T2 is a relay node selection section. The second section T2 is a section in which the pilot tones are transmitted by the relay nodes receiving the initial vehicle message. The transmitting node is the minimum value of the signal-to-noise ratio of each of the neighboring nodes (

) Can be used as a criterion for selecting a relay node. Minimum value of signal to noise ratio (

) Represents the maximum value of signal quality that a transmitting node can provide.

)을 획득한다. 제 i 릴레이 노드에서 파일롯 톤의 송신을 위한 시구간(

)은 하기의 수학식 4에 나타내었다.For example, the i-th relay node uses a neighbor node information table that manages its neighbor node information to determine the minimum value of the signal-to-noise ratio (

). Time period for transmission of a pilot tone in the i th relay node

) Is shown in Equation 4 below.

는 최대 타임아웃(timeout) 구간이다.

은 제 i 릴레이 노드의 신호 대 잡음비이고,

는 최대 신호 대 잡음비 값이다.here,

Is the maximum timeout period.

Is the signal-to-noise ratio of the i th relay node,

Is the maximum signal-to-noise ratio value.

)은 하기의 수학식 5에 나타내었다.Where the maximum timeout interval (

) Is shown in Equation 5 below.

는 파일롯 톤 전송 시간이고, 일예로, 32

일 수 있다. 여기서, c는 시스템 파라미터로서 미리 설정되는 값이다. 제 i 릴레이 노드는 시구간(

)에 대응되는 타이머를 구동시킨다.here,

Is the pilot tone transmission time, for example, 32

Lt; / RTI > Here, c is a value preset as a system parameter. The i relay node has a time period (

The timer corresponding to) is driven.

개의 파일롯 톤을 수신한 제 i 릴레이 노드는 메시지의 수신을 대기하는 리스닝 모드로 동작한다. 하지만, 제 i 릴레이 노드는 타이머의 구동 만료 전에 다른 노드들로부터

개의 파일롯 톤을 수신하지 않고 만료되면, 릴레이 노드 선택에 따른 파일롯 신호를 송신한다.The i-th relay node may be disconnected from other nodes before the timer expires.

The i-th relay node which has received 10 pilot tones operates in a listening mode waiting for reception of a message. However, the i th relay node may be disconnected from other nodes before the timer expires.

When the pilot tones expire without receiving the pilot tones, a pilot signal according to the relay node selection is transmitted.

개의 릴레이 노드를 선택할 수 있다.In addition, the second section T2 is a section in which a pilot tone is transmitted according to completion of relay node selection in a transmitting node that receives pilot tones of all selected relay nodes. At this time, when the transmitting node receives all pilot tones from all selected relay nodes, the transmitting node determines that the selection of the relay node is successful. Thereafter, the transmitting node transmits its pilot tone at the end of the relay node selection interval. Where the transport node is

Relay nodes can be selected.

번 반복 수행할 수 있다.If no pilot tone is received from all selected relay nodes, the transmitting node waits in the initial broadcasting mode, which is an operation mode for broadcasting a vehicle message. The transmitting node broadcasts the initial vehicle message in the repetitive transmission interval of the next vehicle message. That is, the transmitting node performs the initial broadcasting operation again. Upon successful selection of the relay node, the transmitting node k-coordinates the cooperative transmission of vehicle messages.

Can be repeated once.

The third section T3 is a vehicle message cooperative transmission section. In the third section T3, the transmitting node and the relay node cooperate to transmit the vehicle message to the target node. The third section T3 includes a fourth section T4 and a fifth section T5.

The fourth section T4 is a guard section for vehicle message transmission. The fourth section T4 may be referred to as a short inter frame space (SIFS). The fourth section T4 is a guard interval from the completion of transmission of the pilot tone at the transmitting node to the start of cooperative transmission of vehicle messages between the transmitting vehicle and the relay nodes.

The fifth section T5 is a vehicle message cooperative transmission section. In the fifth section T5, the transmitting node and the relay node cooperatively transmit a vehicle message for the target node. The fifth section T5 transmits the same vehicle message encoded in each of the transmitting node and the relay node. In this case, each of the vehicle messages transmitted from the transmitting node and the relay node may be encoded by a space-time block coding (STBC) scheme.

The P time slot 250 includes a second section T2 and a third section T3. The P time slot 250 is a time slot after successfully selecting a relay node through the first time slot 210.

The P th time slot 250 is a section in which the vehicle message is repeatedly transmitted in a time section of a preset period between the transmitting node and the relay node. Here, the transmitted vehicle message is a vehicle message included in the initial vehicle message.

보다 작은 경우에만 협력 전송을 수행한다.In the second period T2, the transmitting node and the relay node transmit pilot tones to each other to obtain information on the channel state. At this time, the transmitting node and the relay node reduce the value of k by 1 before performing the cooperative transmission of the vehicle message. At this time, the transmitting node and the relay node have a value of k

Only cooperative transmission is performed if smaller.

)으로 설정한다. 메시지의 잔류 수명(

)은 하기의 수학식 6에 나타내었다.Neighboring nodes of the transmitting node that have successfully received the vehicle message establish a network allocation vector (NAV) and delay the message transmission until all repeated transmissions are completed. The duration of the network allocation vector (NAV) indicates that the neighboring nodes of senders that successfully receive an emergency message are

Set to). The remaining life of the message (

) Is shown in Equation 6 below.

, L은 차량 메시지에 포함되어 있다. 전송 노드, 릴레이 노드, 네트워크 할당 벡터가 설정된 전송 노드와 릴레이 노드의 이웃 노드를 제외하고, 파일롯 톤을 수신한 노드는 제 2 구간과 제 3 구간에 소요되는 시간을 네트워크 할당 벡터에 적용한다. 여기서 네트워크 할당 벡터는 차량 메시지들 간의 충돌 방지를 위해 노드에 설정되는 벡터값이다.P, k,

, L is included in the vehicle message. Except for the transmitting node, the relay node, and the transmitting node to which the network allocation vector is set and the neighboring nodes of the relay node, the node that receives the pilot tone applies the time required for the second and third intervals to the network allocation vector. Here, the network allocation vector is a vector value set in the node to prevent collision between vehicle messages.

Here, a detailed description of the third section T3 will be described with reference to the description of the first time slot 210.

5 is a flowchart illustrating a vehicle message transmission operation of a transmitting node according to an embodiment of the present invention.

Referring to FIG. 5, the transceiver 110 receives beacon signals from neighboring vehicles located in the target area (S110). The transceiver 110 outputs the received beacon signals to the neighbor node information collector 120.

The node information collecting unit 120 measures signal strength and signal reception probability for each of the neighboring vehicles by using the received beacon signals (S120). The node information collector 120 manages signal strength and signal reception probability of each of the neighboring vehicles through the neighbor node information table. The node information collector 120 updates the changed signal strength and signal reception probability at intervals of a predetermined period. The node information collecting unit 120 provides the message generating unit 140 with neighbor node information managed through the neighbor node information table.

The message generator 140 selects the target vehicle using the neighbor node information in step S130. The message generator 140 selects a target node using a signal reception probability from neighboring node information for selecting a target node.

The sensor unit 130 determines whether an emergency occurs in the vehicle from sensing information sensed through the plurality of sensors attached to the vehicle (S140). If the emergency situation does not occur in the determination of step S140, the sensor unit 130 proceeds to step S110.

If the emergency situation occurs in the determination of step S140, the sensor unit 130 proceeds to step S150. In this case, the sensor unit 130 outputs emergency situation occurrence information according to an emergency occurrence to the message generator.

The message generator 140 initially broadcasts the vehicle message according to the emergency occurrence information (S150).

The message generator 140 selects a relay node using the neighbor node information (step S160). The message generator 140 selects, for example, a relay node capable of obtaining a diversity gain based on a minimum value of signal strength (signal-to-noise ratio) among neighboring node information.

The message generator 140 receives pilot tones from the selected relay nodes (S170).

개의 파일롯 톤을 송수신부(110)를 통해 수신하였는지 판단한다(S180단계). S180단계의 판단결과 미리 설정된 일정 시구간 내에서

개의 파일롯 톤을 모두 수신하지 못하면, 메시지 생성부(140)는 S150단계로 진행한다.The message generator 140 corresponds to the number of all selected relay nodes.

It is determined whether the pilot tone has been received through the transceiver 110 (step S180). As a result of the determination in step S180, within a predetermined time period.

If not receiving all of the pilot tones, the message generating unit 140 proceeds to step S150.

개의 파일롯 톤을 모두 수신하면, 메시지 생성부(140)는 S190단계로 진행한다.As a result of the determination in step S180, within a predetermined time period.

If all of the pilot tones are received, the message generator 140 proceeds to step S190.

The transmitter / receiver 110 transmits the vehicle message to the target nodes together with the selected relay nodes at a predetermined time interval (S190). In this case, the transceiver 110 transmits the vehicle message generated by the message generator 140 and is a vehicle message included in the initial vehicle message. The transceiver 110 may cooperatively transmit the vehicle message together with the relay nodes a preset number of times in each of a plurality of preset time periods.

The transceiver 110 terminates the transmission of the vehicle message.

6 illustrates a signal-to-noise ratio of neighbor nodes for selecting a relay node for relaying a vehicle message according to the present invention.

Referring to FIG. 6, the transmitting node 30 measures signal strength, that is, signal to noise ratio, using a signal received from each of a plurality of nodes (first node, second node, and third node).

)을 측정한다. 여기서,

은 전송 노드와 복수개의 차량들 각각 간의 채널 상태를 나타낸다. 또한,

은 타겟 노드에게 차량 메시지 전송을 위해 보장되는 신호 품질의 최소값이다.At this time, the transmitting node 30 is the minimum value of the signal-to-noise ratio of each of the plurality of nodes within a predetermined time period (

). here,

Denotes a channel state between the transmitting node and each of the plurality of vehicles. Also,

Is the minimum value of the signal quality guaranteed for vehicle message transmission to the target node.

)를 2라고 가정하면, 전송 노드(30)는

의 최소값이 큰 제 2 노드와 제 1 노드를 릴레이 노드로 선택할 수 있다.For example, the number of selected relay nodes (

Assuming 2, the transmitting node 30

The second node and the first node having a large minimum value may be selected as the relay node.

7 illustrates a target area of a vehicle for transmitting a vehicle message according to an exemplary embodiment of the present invention.

Referring to FIG. 7, the target area 310 is an area around the first vehicle 311. The target area 310 includes the first vehicle 311, the second vehicle 312, the third vehicle 313, the fourth vehicle 314, the fifth vehicle 315, the sixth vehicle 316, and the seventh. A vehicle 317, and an eighth vehicle 318. At this time, each of the vehicles 311, 312, 313, 314, 315, 316, 317, and 318 travels based on the lane 320 located on the road. The driving direction 300 of each vehicle is shown.

The target area 310 is a vehicle message reception possible area according to transmission of a vehicle message (or vehicle message) of the first vehicle 311. Therefore, the first vehicle 311 may transmit a vehicle message to all neighboring vehicles 312, 313, 314, 315, 316, 317, and 318 located in the target area.

Meanwhile, each of the first to eighth vehicles 311 to 318 periodically transmits or receives a message to each other. The periodically transmitted and received messages are beacon messages (or beacon signals).

The first vehicle 311 corresponds to the transmitting node. That is, the first vehicle 311 is a transmitting node that transmits a vehicle message. The first vehicle 311 may receive beacon signals from other vehicles. The first vehicle 311 uses beacon signals to select a target node from among neighboring vehicles 312, 313, 314, 315, 316, 317, and 318 that may have a vehicle message transmission error. That is, the target node is a vehicle having a high probability of failing to receive a vehicle message, and thus it is difficult to guarantee the reliability of the vehicle message. In this case, it is assumed that the target nodes are the fourth vehicle 314 and the fifth vehicle 315.

The first vehicle 311 generates a vehicle message. The vehicle message may include, for example, information for notifying occurrence of an emergency situation of the first vehicle 311. The first vehicle 311 broadcasts the vehicle message. In this case, the vehicle message includes identifier information for the target nodes 314 and 315 and a transmission pattern of the vehicle message to be repeatedly transmitted for cooperative transmission.

The first vehicle 311 may select a relay node for cooperative transmission of vehicle messages to the target nodes 314 and 315. The first vehicle 311 may select the relay node in order of the smallest signal-to-noise ratio among the neighboring vehicles 312, 313, 314, 315, 316, 317, and 318. In this case, it is assumed that the selected relay node is the second vehicle 312, the third vehicle 313, and the sixth vehicle 316.

When the selection of the relay nodes 312, 313, 316 is complete, the first vehicle 11 cooperates with the relay nodes to transmit a vehicle message of a predetermined transmission pattern. Thereafter, the first vehicle 11 repeatedly transmits the vehicle message through the preset time period together with the relay nodes 312, 313, and 316 at a predetermined number of times.

As a result, the target nodes may obtain a diversity gain by receiving the same vehicle message repeatedly through the first vehicle 311 and the relay vehicles.

Here, the first vehicle 311 may correspond to the transmission node of the present invention, and the remaining neighboring vehicles 312, 313, 314, 315, 316, 317, and 318 may be neighbor nodes.

That is, the transmitting node of the present invention selects a relay node having a high minimum of channel quality in order to improve the reliability of message transmission, and repeatedly transmits a message in cooperation with the selected relay node. Through this, target nodes having a high probability of failing to receive a message may obtain a diversity gain.

As an example, the transmission node proposed in the present invention describes a vehicle for vehicle message transmission as an example, but may be applied to devices other than the vehicle. Therefore, the message transmission scheme of the present invention can be used not only for vehicle message transmission but also for transmission of other messages.

10: target node 20: relay node
30: transport node
110: transceiver 120: node information collector
121: signal strength measurement unit 122: signal reception probability measurement unit
123: neighbor node information management unit 130: sensor unit
140: message transceiver
311, 312, 313, 314, 315, 316, 317, 318: vehicles

Claims (16)

delete In the message transmission method of the transmitting node,
Broadcasting an initial message for message transmission;
Selecting at least one neighboring node among the neighboring nodes as the relay node, wherein the lowest value of the signal-to-noise ratio for each of the received signals from the neighboring nodes is higher than the lowest value of the signal-to-noise ratio of the other neighboring nodes;
Transmitting a message having a transmission pattern included in the initial message together with the selected at least one relay node to a selected target node based on the received signals; And
Selecting the number of target nodes based on a signal reception probability for each of the received signals. The method of claim 2,
The step of selecting the target node
Selecting a neighbor node as a target node having a smaller signal-to-noise ratio than other neighbor nodes. The method of claim 2,
And the message is a message for notifying occurrence of an emergency situation occurring at the transmitting node. In the message transmission method of the transmitting node,
Broadcasting an initial message for message transmission;
Selecting at least one neighboring node among the neighboring nodes as the relay node, wherein the lowest value of the signal-to-noise ratio for each of the received signals from the neighboring nodes is higher than the lowest value of the signal-to-noise ratio of the other neighboring nodes;
Transmitting a message having a transmission pattern included in the initial message together with the selected at least one relay node to a selected target node based on the received signals;
Including,
Selecting the at least one relay node
And upon receiving pilot signals from all selected relay nodes, completing selection of the relay node by transmitting a pilot signal corresponding to the pilot signals. In the message transmission method of the transmitting node,
Broadcasting an initial message for message transmission;
Selecting at least one neighboring node among the neighboring nodes as the relay node, wherein the lowest value of the signal-to-noise ratio for each of the received signals from the neighboring nodes is higher than the lowest value of the signal-to-noise ratio of the other neighboring nodes; And
Transmitting a message having a transmission pattern included in the initial message together with the selected at least one relay node to a selected target node based on the received signals;
Including
Selecting the at least one relay node
If not receiving pilot signals from all selected relay nodes, broadcasting the initial message. delete A node information collector configured to collect neighbor node information from received signals of the neighbor nodes;
A message processing unit which generates a message for transmission to the neighbor nodes and selects a target node having a possibility of transmission error of the message and a relay node for cooperative transmission of the message using the neighbor node information; And
And a transceiver configured to receive the received signals from the neighbor nodes and cooperatively transmit the message to the target node with the relay node.
The message processor selects, as the relay node, at least one neighboring node among the neighboring nodes whose minimum value of the signal-to-noise ratio for each of the received signals is higher than a minimum value of the signal-to-noise ratio of other neighboring nodes.
And selecting a target node based on a signal-to-noise ratio of each of the received messages and a reception error probability of each of the received messages. The method of claim 8,
And the message processing unit sets the number of the target nodes based on the reception error probability. The method of claim 9,
And the message processing unit selects a neighbor node having a smaller signal-to-noise ratio than other neighbor nodes as a target node. The method of claim 8,
And the transmitting and receiving unit transmits a pilot signal corresponding to the pilot signal when receiving the pilot signals from all the selected relay nodes. The method of claim 11,
And the transmitting / receiving unit broadcasts the message if it does not receive a pilot signal from all the selected relay nodes. The method of claim 8,
The transmitting and receiving unit is a transmission node for encoding the messages by a space-time encoding method. The method of claim 8,
The transmitting and receiving unit transmits the message repeatedly with the relay node a predetermined number of times over a predetermined time interval. The method of claim 8,
The transmitting node
Transmission node further comprising a sensor unit for detecting an emergency of the vehicle. The method of claim 15,
The message generator is a transmission node for generating a message for notifying the emergency situation according to the emergency situation detection.

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