KR102424661B1 - Control method of vehicle communication device - Google Patents

Abstract

The present invention relates to a control method of a vehicle communication device, the vehicle communication device receiving a V2X message, the vehicle communication device determining a communication environment state, if it is determined that the communication environment is good, the vehicle communication device is high Demodulating and decoding the message at a data rate or a low code rate and when it is determined that the communication environment is not good, the vehicle communication device demodulates and decodes the message at a low data rate or a high code rate and decoding.

Description

Control method of vehicle communication device {CONTROL METHOD OF VEHICLE COMMUNICATION DEVICE}

The present invention relates to a method of controlling a vehicle communication device, and more particularly, to a control method of a vehicle communication device performing V2X communication.

Vehicle-to-Vehicle Communication refers to a technology in which a vehicle and a vehicle exchange information with each other using network, communication, and Internet technology on their own. and can serve as an assistant to the driver. For example, the vehicle-to-vehicle communication device may be connected to a brake or control system of a vehicle to perform emergency braking or warn a driver of an emergency situation.

Vehicle-to-infrastructure communication is a vehicle communication infrastructure technology by communication between vehicles and roadside devices, through which vehicles can receive traffic information and safety support services.

It is common to collectively refer to such vehicle communication as V2X (Vehicle to Everything Communication).

Recent vehicles are equipped with a V2X communication device, and through this, messages related to safe driving are provided from nearby vehicles or roadside devices to prevent traffic accidents and to implement a safe driving function in many cases.

Therefore, for safety, it is important to ensure the processing speed and reliability of V2X messages processed in the vehicle.

Meanwhile, the background technology of the present invention is disclosed in Korean Patent Laid-Open No. 10-2017-0044877 (2017.04.26).

It is an object of the present invention to provide a control method of a vehicle communication device that enables the application of an efficient communication method without reducing the reliability and processing speed of the V2X message.

A method for controlling a vehicle communication device according to an aspect of the present invention includes: receiving, by the vehicle communication device, a V2X message; determining, by the vehicle communication device, a communication environment state; demodulating and decoding, by the vehicle communication device, the message at a high data rate or a low code rate, if it is determined that the communication environment is good; and if it is determined that the communication environment is not good, the vehicle communication device demodulating and decoding the message at a low data rate or a high code rate.

In the step of determining the communication environment state in the present invention, the vehicle communication device includes a received signal power strength (RSSI), an event flag value (EventFlags) of a previously received message, and the number of objects that have communicated within a set distance. It is characterized in that the function value of the function using as a variable is calculated and compared with a threshold value.

In the present invention, when the event flag value of the previously received message does not exist, the vehicle communication device processes the corresponding value as 0.5.

The step of demodulating and decoding the message at the high data rate of the present invention comprises: demodulating and deinterleaving, by the vehicle communication device, the message at the high data rate; decoding the deinterleaved data by the vehicle communication device; and rearranging, by the vehicle communication device, the decoded data in a message format.

The step of demodulating and decoding the message at the low data rate of the present invention includes: the vehicle communication device demodulating the message at the low data rate; and decoding the demodulated data by the vehicle communication device.

A method of controlling a vehicle communication device according to an aspect of the present invention includes the steps of separating important data and the remaining data from a message to be transmitted by the vehicle communication device; coding the separated data by the vehicle communication device; and transmitting, by the vehicle communication device, by interleaving the coded data.

In the present invention, it is characterized in that the vehicle path history (Path History) or non-safety applications (Non-safety applications) related data is separated into the remaining data.

A method for controlling a vehicle communication device according to another aspect of the present invention includes: receiving, by the vehicle communication device, a V2X message; The vehicle communication device, the received signal power strength (RSSI), the event flag value (EventFlags) of a previously received message, and a function value of a function using at least one of the number of objects that have communicated within a set distance as a variable calculating; demodulating and decoding, by the vehicle communication device, the message at a high data rate if the calculated function value is greater than a threshold value; and if the calculated function value is not greater than the threshold value, the vehicle communication device demodulating and decoding the message at a low data rate.

A method of controlling a vehicle communication device according to another aspect of the present invention comprises: receiving, by the vehicle communication device, a V2X message; The vehicle communication device, the received signal power strength (RSSI), the event flag value (EventFlags) of a previously received message, and a function value of a function using at least one of the number of objects that have communicated within a set distance as a variable calculating; demodulating and decoding, by the vehicle communication device, the message at a low code rate when the calculated function value is greater than a threshold value; and if the calculated function value is not greater than the threshold value, the vehicle communication device demodulating and decoding the message at a high code rate.

The control method of the vehicle communication apparatus according to the present invention has an effect of allowing a large amount of data to be received or reliability of received data and messages by determining a demodulation and decoding method by determining a communication environment state of a vehicle.

1 is a flowchart illustrating a process of transmitting a message in a method for controlling a vehicle communication device according to an embodiment of the present invention.
2 is an exemplary diagram for explaining a process of transmitting a message in a method for controlling a vehicle communication device according to an embodiment of the present invention.
3 is an exemplary diagram for explaining a hierarchical model of a vehicle communication device according to an embodiment of the present invention.
4 is a flowchart illustrating a process of receiving a message in a method for controlling a vehicle communication device according to an embodiment of the present invention.
5 to 7 are exemplary views for explaining a method of receiving a message in the control method of the vehicle communication device according to an embodiment of the present invention.
8 is an exemplary diagram for explaining a process of transmitting a message in a method for controlling a vehicle communication device according to another embodiment of the present invention.
9 is a flowchart illustrating a process of receiving a message in a method for controlling a vehicle communication device according to another embodiment of the present invention.
10 and 11 are exemplary views for explaining a method of receiving a message in a method for controlling a vehicle communication device according to another embodiment of the present invention.
12 is an exemplary diagram for explaining a determination function of a control method of a vehicle communication device according to the present invention.

Hereinafter, an embodiment of a control method of a vehicle communication device according to the present invention will be described with reference to the accompanying drawings. In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators. Therefore, definitions of these terms should be made based on the content throughout this specification.

1. Data rate layered message transmission

1 is a flowchart for explaining a process of transmitting a message in a method for controlling a vehicle communication device according to an embodiment of the present invention, and FIG. 2 is a method for controlling a vehicle communication device according to an embodiment of the present invention It is an exemplary view for explaining a transmission process, and FIG. 3 is an exemplary view for explaining a layer model of a vehicle communication device according to an embodiment of the present invention.

As shown in FIG. 1 , the vehicle communication device first separates important data and the remaining data from the message to be transmitted ( S200 ).

The vehicle communication device may be mounted on a vehicle to perform V2X communication. To this end, the vehicle communication device may include a communication module, an antenna, and the like, and may be designed to comply with specifications of standards (eg, IEEE 802.11p, SAE J2735, SAE J2945, etc.) in the field of vehicle communication.

The vehicle communication device may transmit a V2X message, and for message transmission of the data rate layering method, the vehicle communication device may separate important data and the remaining data from the message to be transmitted, as shown in FIG. 2 .

For example, in the case of transmitting a Basic Safety Message (BSM), the corresponding message includes time information (Time), position information (3D Position, Position Accuracy), speed (Speed), direction (Heading), and steering wheel angle (Steering). Wheel Angle, Acceleration, Brake Status, Vehicle Size, EventFlags, Path History, Path Prediction, Other optional fields ) may be included in the BSM.

This BSM is a message that is broadcast several times per second in each vehicle, and is a message that is basically used for the operation of the safety support system using V2X communication.

According to the above-described vehicle communication standard, in this BSM, the route history occupies about half of the data of the entire message, and information such as location information and speed is more important than the route history for vehicle safety, so vehicle communication The device may classify the route history as less important data (residual data), and classify data other than the route history as important data.

Or, the vehicle communication device includes at least a physical layer (Physical Layer, 101), a MAC layer (Media Access Control (MAC) layer, 102) and an application layer (Application layer, 103, 104) as shown in FIG. It can be configured as a hierarchical model.

At this time, the application layer can be divided into safety applications (Safety Applications, 103) and non-safety applications (Non-Safety Applications, 104), and the vehicle communication device can separate non-safety application-related data into less important data. .

Meanwhile, the layer model may be an Open Systems Interconnection Reference Model (OSI).

Then, the vehicle communication device codes each of the separated data (S210). Here, the coding of the data may include encoding and the like, and may be performed according to a standardized method, so a detailed description thereof will be omitted.

Thereafter, the vehicle communication device transmits the coded data by interleaving ( S220 ). That is, the vehicle communication device may transmit a message by alternately disposing coded important data and coded less important data, and one square in FIG. 2 may mean 1 bit, and a plurality of bits may mean

Meanwhile, in the present invention, coding (decoding) and modulation (demodulation) have been described separately for each operation.

2. Data rate tiered message reception

4 is a flowchart for explaining a process of receiving a message in a method for controlling a vehicle communication device according to an embodiment of the present invention, and FIGS. 5 to 7 are a control method for a vehicle communication device according to an embodiment of the present invention. It is an exemplary diagram for explaining a method of receiving a message.

As shown in FIG. 4 , the vehicle communication device receives a message ( S300 ) and determines a demodulation and decoding method ( S310 ). For example, the vehicle communication device is a function (determining) in which at least one or more of the received signal power strength (RSSI), the event flag value (EventFlags) of a previously received message, and the number of objects that have communicated within the set distance are variables. The demodulation and decoding method may be determined by calculating the function value U of the function), and a more detailed description of the determination function will be described later.

According to the result of the step (S310), if the calculated function value is greater than the threshold value (U _th ) (YES in S320), the vehicle communication device demodulates and decodes the message received in the step (S300) at a high data rate. Interleaving (deinterleaving) (S330).

Here, the high data rate refers to a first data rate that is relatively larger than a low data rate (second data rate) to be described later, and the data rate refers to a ratio of demodulated data.

That is, as shown in FIG. 5 , when the calculated function value is greater than the threshold value, the vehicle communication device demodulates a message received at a high data rate, and performs deinterleaving corresponding to the interleaving in step S220 described above. do.

Demodulation of a high data rate and demodulation of a low data rate will be described with reference to FIG. 6 .

For example, as shown in FIG. 6 , when the transmitting side transmits 16-QAM (Quadrature Amplitude Modulation) data, and when demodulating at a high data rate, demodulation is performed with 16-QAM, and the low data When demodulation is performed at a rate, it may be configured to perform demodulation using Quadrature Phase Shift Keying (QPSK).

That is, if 1011 is demodulated when demodulating at a high data rate, 11 can be demodulated when demodulating at a low data rate.

Next, the vehicle communication device decodes the deinterleaved data, respectively (S340). That is, the vehicle communication device performs decoding corresponding to the coding in step S210 described above.

Thereafter, the vehicle communication device rearranges the decoded data in a message format (S350). That is, the classification of data according to the above-described step (S200) may be performed according to a preset criterion, and at this time, the location (order) of the classified data can be grasped in advance, so that the vehicle communication device according to the above-described step (S200) The decoded data may be rearranged in a message format corresponding to the classification of the data.

This demodulation and decoding process may be performed in the MAC layer 102, and the rearranged message is delivered to an upper layer.

Meanwhile, according to the result of step S310, if the calculated function value is not greater than the threshold value (No in S320), the vehicle communication device demodulates the message received in step S300 at a low data rate (S360). . That is, if the calculated function value is not greater than the threshold value, the vehicle communication device demodulates the received message at a low data rate. However, even if the amount of demodulated data is small, as shown in FIG. 7 , all important data can be demodulated.

Then, the vehicle communication device decodes the demodulated data (S370). That is, the vehicle communication device performs decoding corresponding to the coding in step S210 described above.

Also, when demodulation and decoding are performed at a low data rate, the order of data does not need to be rearranged, so the rearrangement process may not be performed. However, depending on the design, it may be configured to insert the dummy data at a location of less important data.

3. Low code rate message transmission

8 is an exemplary diagram for explaining a process of transmitting a message in a method for controlling a vehicle communication device according to another embodiment of the present invention.

In the present invention, the low code rate (first code rate) means a code rate generally used in V2X communication or a code rate relatively lower than a code rate (second code rate) according to the above-described vehicle communication standard.

For example, when the commonly used code rate is 1/3, the vehicle communication device can transmit the message by coding the information bit at a low code rate (1/6 code rate) as shown in FIG. 8 . have.

4. Message reception in code rate layered method

9 is a flowchart for explaining a process of receiving a message in a control method of a vehicle communication device according to another embodiment of the present invention, and FIGS. 10 and 11 are a control method of a vehicle communication device according to another embodiment of the present invention. It is an exemplary diagram for explaining a method of receiving a message.

As shown in FIG. 9 , the vehicle communication device receives a message (S400) and determines a demodulation and decoding method (S410). For example, the vehicle communication device may determine the demodulation and decoding method by calculating the function value U of the determination function.

According to the result of the step (S410), if the calculated function value is greater than the threshold value (U _th ) (YES in S420), the vehicle communication device demodulates and decodes the message received in the step (S400) with a low code rate. do (S430).

That is, as shown in FIG. 10 , the vehicle communication device may demodulate a received message with a low code rate and decode it with a low code rate. Here, demodulation with a low code rate may be performed in the same manner as the high data rate demodulation shown in FIG. 6 described above.

On the other hand, according to the result of step S410, if the calculated function value is not greater than the threshold value (No in S420), the vehicle communication device demodulates and decodes the message received in step S400 with a high code rate. (S440).

That is, as shown in FIG. 11 , the vehicle communication device may demodulate a received message with a high code rate and decode it with a high code rate. Here, demodulation with a high code rate may be performed in the same manner as the low data rate demodulation shown in FIG. 6 described above.

5. Judgment function

12 is an exemplary diagram for explaining a determination function of a control method of a vehicle communication device according to the present invention.

In the present invention, the decision function is for determining a demodulation and decoding method of a received message, and as described above, received signal power strength (RSSI), event flag values (EventFlags) of a previously received message, and communication within a set distance It is a function that takes as a variable at least one or more of the number of objects that have been exchanged.

That is, the determination function is for determining the current communication environment state. If the function value of the determination function is greater than a preset threshold value, it can be determined that the communication environment is good, and if the function value of the determination function is greater than the preset threshold value, It may be determined that the communication environment is not good.

For example, such a decision function U may be designed as in Equation 1 below.

(Equation 1)

U = w ₁ (RSSI-a) + w ₂ ×EventFlags - w ₃ ×VDR

Here, w ₁ , w ₂ , and w ₃ denote the weight of each variable, a denotes a standard RSSI value as a constant, and VDR denotes the number of objects that communicated within a set distance. For example, a value of a may be an RSSI value obtained when a PER of 10% is obtained when a 12Mbps, 16QAM with 1/2 rate coding, and PSDU 400 byte communication method is used.

That is, it can be determined that the better the received signal power strength, the better the communication environment is as the number of objects that have communicated within the set distance is reduced.

In addition, the event flag is set to 1 when an important vehicle event occurs (eg, hard braking, airbag deployment), and the default value is 0, and is included in the BSM.

That is, since an important event has occurred when the event flag is 1, the demodulation and decoding method of the received message may be determined by further considering the event flag value of the previously received message in the communication environment state.

At this time, the value of this event flag can be checked in the application layer 103, and demodulation and decoding are performed in the MAC layer 102. Therefore, in the present invention, the received message in consideration of the event flag value of the previously received message. Determining the demodulation and decoding method of

At this time, the previously received message is referenced for each vehicle, and when the event flag value of the previously received message does not exist (eg, if a message has never been received from the vehicle, a message has been received from the vehicle but the event In case the flag value does not exist), the decision function value can be calculated by treating the corresponding value as 0.5.

If the event flag is set to 1, the cycle of transmitting the message at the message sending end can be quicker, for example, by doubling the number of transmissions, and by minimizing the back off time to keep sending the message. method and the like may be applied.

On the other hand, in the conventional method of applying the same communication method to all vehicles within a cell (communicable distance of the host vehicle), the maximum specification of a communication device mounted on a vehicle is generally for smooth data reception of a vehicle far away from the host vehicle. Communication was performed at a lower bit rate.

However, as shown in FIG. 12 , in general, in the case of RV1 (remote vehicle, vehicle receiving message, 200) located close to HV (host vehicle, vehicle transmitting message, 100), the determination function value is higher than the threshold value. will be large, and in the case of RV2 farther from HV, the judgment function value will be smaller than the threshold value.

That is, in the case of a vehicle close to the host vehicle, since the strength of the received signal is sufficient and the noise is low, communication can be performed at a high bit rate.

In the present invention, a vehicle whose signal-to-interference-plus-noise ratio (SINR) is determined to be good (a vehicle in which the determination function value is greater than a threshold value) receives a message at a high data rate or a low code rate, so that a large amount of data or to increase the reliability of the received data.

In addition, in a vehicle whose SINR is judged to be bad (a vehicle whose determination function value is smaller than a threshold value), a message is received at a low data rate or a high code rate, so that an important message can be reliably received, or the reliability of the received data is lowered to the conventional level. It is possible to improve the data processing speed compared to the case of using only a low coding rate while maintaining

That is, since the control method of the vehicle communication device according to the present invention enables smooth data reception of a distant vehicle even if the bit rate is increased compared to the conventional vehicle communication method, the amount of data can be maintained even when using a lower code rate than the conventional method. In addition, even if a message is received with a high code rate, the code rate according to the conventional method can be maintained.

6. Examples

Various embodiments of the vehicle communication device to which the control method according to the present invention is applied may be possible.

In an embodiment of the present invention, the vehicle communication device may be configured to transmit and receive a data rate layered message transmission/reception method.

In another embodiment of the present invention, the vehicle communication device may be configured to transmit a message with a low code rate and receive the message in a code rate layered manner.

In another embodiment of the present invention, the vehicle communication device may be configured to operate by selecting transmission/reception of a message using a data rate layering method, transmitting a message at a low code rate, and receiving a message using a code rate layering method.

In this case, the selection of both methods may be selected according to data included in a previously received message, or may be determined by a user's pre-selection.

Although the present invention has been described with reference to the embodiment shown in the drawings, this is merely exemplary, and it is understood that various modifications and equivalent other embodiments are possible by those of ordinary skill in the art. will understand Therefore, the technical protection scope of the present invention should be defined by the following claims.

100: host vehicle
200, 300: remote vehicle

Claims (11)

Receiving the vehicle communication device V2X message;
The vehicle communication device calculates a function value of a function using the received signal power intensity (RSSI), the event flag value (EventFlags) of a previously received message, and the number of objects that have communicated within the set distance as variables, and calculates the threshold value and determining a communication environment state by comparing;
Demodulating and decoding, by the vehicle communication device, the message at a high data rate equal to the transmission side data rate or a corresponding low code rate when the communication environment is good; and
and demodulating and decoding, by the vehicle communication device, the message at a low data rate smaller than a transmission side data rate or a corresponding high code rate when it is determined that the communication environment is not good.
delete The method of claim 1,
The vehicle communication device, when there is no event flag value of the previously received message, the control method of the vehicle communication device, characterized in that processing the value as 0.5.
According to claim 1,
Demodulating and decoding the message at the high data rate comprises:
demodulating and deinterleaving, by the vehicle communication device, the message at the high data rate;
decoding the deinterleaved data by the vehicle communication device; and
and rearranging, by the vehicle communication device, the decoded data in a message format.
5. The method of claim 4,
Demodulating and decoding the message at the low data rate comprises:
demodulating, by the vehicle communication device, the message at the low data rate; and
and decoding, by the vehicle communication device, demodulated data.
The method of claim 1,
separating important data and remaining data from the message to be transmitted by the vehicle communication device;
coding the separated data by the vehicle communication device; and
The control method of the vehicle communication device, characterized in that it further comprises the step of transmitting the coded data by interleaving (interleaving) the vehicle communication device.
7. The method of claim 6,
A method of controlling a vehicle communication device, characterized in that data related to a vehicle's path history or non-safety applications are separated into the remaining data.
Receiving the vehicle communication device V2X message;
The vehicle communication device, the received signal power strength (RSSI), the event flag value (EventFlags) of a previously received message, and a function value of a function using at least one of the number of objects that have communicated within a set distance as a variable calculating;
if the calculated function value is greater than a threshold, demodulating and decoding, by the vehicle communication device, the message at a high data rate equal to a data rate of a transmitting side; and
and if the calculated function value is not greater than the threshold value, demodulating and decoding, by the vehicle communication device, the message at a lower data rate than a transmitting-side data rate.
9. The method of claim 8,
Demodulating and decoding the message at the high data rate comprises:
demodulating and deinterleaving, by the vehicle communication device, the message at the high data rate;
decoding the deinterleaved data by the vehicle communication device; and
and rearranging, by the vehicle communication device, the decoded data in a message format.
10. The method of claim 9,
Demodulating and decoding the message at the low data rate comprises:
demodulating, by the vehicle communication device, the message at the low data rate; and
and decoding, by the vehicle communication device, demodulated data.
Receiving the vehicle communication device V2X message;
The vehicle communication device, the received signal power strength (RSSI), the event flag value (EventFlags) of a previously received message, and a function value of a function using at least one of the number of objects that have communicated within a set distance as a variable calculating;
if the calculated function value is greater than a threshold value, demodulating and decoding, by the vehicle communication device, the message at a low code rate corresponding to the same data rate as the transmitting data rate; and
If the calculated function value is not greater than the threshold value, the vehicle communication device control method of a vehicle communication device comprising the step of demodulating and decoding the message at a high code rate corresponding to a data rate lower than the data rate of the transmission side .

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