KR102469697B1 - Vehicle localization method for urban environment using road traffic infrastructure and wireless communication technology - Google Patents

Abstract

The present embodiments provide a traffic signal system and a vehicle capable of estimating the location and moving direction of a vehicle according to the driving state of the vehicle at an intersection based on wireless or mobile communication and improving positioning accuracy.

Description

Location Estimation Method of Urban Vehicle Using Road Traffic Facility and Wireless Communication Technology

The technical field to which the present invention belongs relates to a traffic signal system capable of estimating the location of a vehicle for urban use and a vehicle communicating with the traffic signal system.

The contents described in this part merely provide background information on the present embodiment and do not constitute prior art.

Although vehicle position estimation requires very precise positioning accuracy, conventional position estimation techniques using GPS (Global Positioning System) do not have high positioning accuracy in an urban environment.

US 2016/0035223 (2016.02.04.) KR 10-1962181 (2019.03.20.) KR 10-2019-0061395 (2019.06.05.) KR 10-2018-0040760 (2018.04.23.)

Embodiments of the present invention are mainly aimed at estimating the location and moving direction of a vehicle according to the driving state of the vehicle at an intersection based on communication between the vehicle and the traffic signal system.

Other non-specified objects of the present invention may be additionally considered within the scope that can be easily inferred from the following detailed description and effects thereof.

According to one aspect of this embodiment, in a vehicle, a first communication unit for transmitting and receiving a message with a traffic signal system; It is connected to the first communication unit, divides the driving state of the vehicle into a stop state, a departure state, and a moving state, and transmits and receives messages to and from the traffic signal system according to the stop state, the departure state, and the moving state. a first processing unit that processes differently; and a moving device connected to the first processing unit and moving the vehicle.

The traffic signal system includes a plurality of traffic lights installed at different locations at an intersection, and in the stopped state, the first communication unit periodically transmits an arrival message to the traffic signal system, When the signal is red, the first communication unit receives an arrival response message and a stop status message from the traffic signal system, and the first communication unit transmits a stop status response message and a pilot signal for positioning to the traffic signal system. , The first communication unit may receive a vehicle location message estimated using the arrival time and signal strength of the pilot signal by a plurality of traffic lights installed at different locations in the intersection.

The traffic signal system includes traffic lights installed at a plurality of adjacent intersections, and in the starting state, when the traffic signal for the driving direction of the vehicle is converted to a green signal, the first communication unit can depart from the traffic signal system. message, and the first communication unit receives the departure possibility message and transmits a departure state response message and a pilot signal for positioning to the traffic signal system after a predetermined waiting time has elapsed, and receives the departure state response message One traffic light may deliver a vehicle entry message to the traffic light of the next intersection in consideration of the location and moving direction of the vehicle estimated using the pilot signal.

The traffic signal system includes traffic lights installed at a plurality of adjacent intersections, and in the departure state, without considering the traffic signal for the traveling direction of the vehicle, the first communication unit transmits a departure state response message and The traffic light that transmits the pilot signal for positioning and receives the departure state response message can forward the vehicle entry message to the traffic light at the next intersection in consideration of the location and moving direction of the vehicle estimated using the pilot signal.

The traffic signal system includes traffic lights installed at a plurality of adjacent intersections, and in the moving state, the first communication unit periodically transmits an arrival message to the traffic signal system, and the traffic signal for the vehicle's traveling direction is green. signal, the first communication unit receives an arrival response message and a movement status message from the traffic signal system, the first communication unit transmits a movement status response message and a pilot signal for positioning to the traffic signal system, The traffic light receiving the status response message transfers the vehicle entry message to the traffic light of the next intersection in consideration of the position and moving direction of the vehicle estimated using the pilot signal, and the traffic light receiving the moving status response message transmits the pilot signal , It is possible to receive a vehicle location message estimated using the moving speed and moving direction of the vehicle.

According to another aspect of the present embodiment, in a traffic signal system, a second communication unit for transmitting and receiving a message to and from a vehicle; and a second processing unit that is connected to the second communication unit and differently processes messages transmitted/received from the vehicle according to driving conditions of the vehicle divided into a stop state, a departure state, and a moving state. do.

The traffic signal system includes a plurality of traffic lights installed at different locations at an intersection, and in the stop state, the second communication unit receives an arrival message from the traffic signal system and transmits a traffic signal for the direction of the vehicle. When a red signal is received, the second communication unit transmits an arrival response message and a stop status message to the vehicle, the second communication unit receives a stop status response message and a pilot signal for positioning from the vehicle, and the second processing unit receives a stop status response message from the vehicle. The location of the vehicle is estimated using the arrival time and signal strength of the pilot signal by a plurality of traffic lights installed at different locations in the intersection, and the second communication unit sends a vehicle location message about the location of the vehicle to the vehicle. can send

The traffic signal system includes traffic lights installed at a plurality of adjacent intersections, and in the departure state, when the traffic signal for the traveling direction of the vehicle is converted to a green light, the second communication unit transmits a departure possible message to the vehicle. The second communication unit receives a departure state response message and a pilot signal for positioning from the vehicle, and the second processing unit estimates the location and movement direction of the vehicle using the pilot signal, and the second communication unit The vehicle entry message can be delivered to the traffic light at the next intersection.

The traffic signal system includes traffic lights installed at a plurality of adjacent intersections, and in the departure state, the second communication unit receives a departure state response message and a pilot signal for positioning from the vehicle before transmitting a departure possibility message to the vehicle. receive, the second processing unit estimates the location and moving direction of the vehicle using the pilot signal, and the second communication unit transmits the vehicle entry message to the traffic light of the next intersection.

The traffic signal system includes traffic lights installed at a plurality of adjacent intersections, and in the moving state, the second communication unit receives an arrival message from the vehicle, and when the traffic signal for the direction of the vehicle is green, the The second communication unit transmits an arrival response message and a movement status message to the vehicle, the second communication unit receives a movement status response message and a pilot signal for positioning from the vehicle, and the second processing unit uses the pilot signal. to estimate the location and moving direction of the vehicle, the second communication unit transmits a vehicle entry message to the traffic light of the next intersection, and the second processing unit detects the vehicle using the pilot signal, the moving speed and the moving direction of the vehicle The location of the vehicle may be estimated, and the second communication unit may transmit a vehicle location message about the location of the vehicle to the vehicle.

As described above, according to the embodiments of the present invention, based on communication between the vehicle and the traffic signal system, there is an effect of estimating the location and moving direction of the vehicle according to the driving state of the vehicle at the intersection and improving the positioning accuracy.

Even if the effects are not explicitly mentioned here, the effects described in the following specification expected by the technical features of the present invention and their provisional effects are treated as described in the specification of the present invention.

1 is a diagram illustrating an intersection according to a traffic signal system.
2 is a block diagram illustrating a vehicle according to an embodiment of the present invention.
3 is a block diagram illustrating a traffic signal system according to another embodiment of the present invention.
4 is a diagram illustrating messages transmitted and received between a vehicle and a traffic signal system in a stopped state according to embodiments of the present invention.
5 is a diagram illustrating messages transmitted and received between a vehicle and a traffic signal system in a starting state according to embodiments of the present invention.
6 is a diagram illustrating messages transmitted and received in a moving state between a vehicle and a traffic signal system according to embodiments of the present invention.

Hereinafter, in the description of the present invention, if it is determined that a related known function may unnecessarily obscure the subject matter of the present invention as an obvious matter to those skilled in the art, the detailed description thereof will be omitted, and some embodiments of the present invention will be described. It will be described in detail through exemplary drawings.

1 is a diagram illustrating an intersection according to a traffic signal system, FIG. 2 is a block diagram illustrating a vehicle according to an embodiment of the present invention, and FIG. 3 illustrates a traffic signal system according to another embodiment of the present invention. It is a block diagram.

In the present invention, the driving state of the vehicle is divided into three categories: stop, departure, and movement. The present invention performs different operations according to the driving state of the vehicle.

At standstill, the traffic signal system performs high-precision localization.

In the starting state, the traffic signal system estimates the moving direction of the vehicle, delivers vehicle entry information to an intersection to be reached when the vehicle proceeds in the estimated moving direction, and performs a hand-off.

In a moving state, the traffic signal system corrects the position in real time to improve estimation accuracy.

In each state, signals are transmitted and received between the vehicle and the system. Depending on each state, vehicles and traffic signal systems exchange different messages. The corresponding message may have different configuration methods and transmission methods according to communication standards used by the system.

The localization system of the present invention can be used using road traffic facilities and infrastructure. In particular, it is possible to estimate the location more accurately by using it in conjunction with the traffic signal system. It can be installed and used on traffic lights existing at intersections.

Wireless communication used in this embodiment can be used according to various communication methods and standards, such as commercial mobile communication technologies (LTE, NR, etc.) and dedicated short range communication (DSRC). For example, next-generation mobile communications such as 5G and 6G can be applied.

The localization system includes a vehicle 100 and a traffic signal system 200 .

The vehicle 100 includes a first communication unit 110 , a first processing unit 120 , and a mobile device 130 . Vehicle 100 may be an autonomous vehicle.

The first communication unit 110 transmits and receives messages to and from the traffic signal system 200 .

The first processing unit 120 is connected to the first communication unit 110 and divides the driving state of the vehicle 100 into a stop state, a departure state, and a moving state. The first processing unit 120 differently processes messages transmitted and received with the traffic signal system 200 according to a stop state, a departure state, and a movement state.

The vehicle 100 may correct its own location information or correct a driving plan using the received location message.

The moving device 130 is connected to the first processing unit 120 and moves the vehicle 100 . It may be a driving device having a kind of wheel.

The traffic signal system 200 includes a second communication unit 210 and a second processing unit 220 . The traffic signal system 200 may include a plurality of traffic lights installed at different locations in an intersection. The traffic signal system 200 may include traffic lights installed at a plurality of adjacent intersections.

The second communication unit 210 transmits and receives messages to and from the vehicle 100 .

The second processing unit 220 is connected to the second communication unit 210, and processes messages transmitted and received with the vehicle differently according to driving conditions of the vehicle classified into a stop state, a departure state, and a moving state.

4 is a diagram illustrating messages transmitted and received between a vehicle and a traffic signal system in a stopped state according to embodiments of the present invention.

The vehicle periodically transmits an ARV message (vehicle arrival information). The traffic light at the intersection receives the ARV message to confirm that the vehicle is entering, and to check the traffic signal in the direction the vehicle is traveling. When the traffic signal for the vehicle's direction is red, the traffic light transmits an ARV ACK message (response to the ARV message) and an SC-A message (confirming that it is in A state) to the vehicle. After receiving the ARV ACK and SC-A, the vehicle stops and transmits an RS (pilot signal for positioning) along with an SC-A ACK message (response to SC-A). After receiving the SC-A ACK, the traffic lights installed at different locations of the intersection estimate the location of the vehicle using the arrival time difference of the RS signal transmitted by the vehicle and the received signal strength difference. After location estimation is completed, the traffic light transmits a LOC message (information about the estimated location) to the vehicle.

In a stopped state, the first communication unit of the vehicle periodically transmits an arrival message through a traffic signal system. When the traffic signal for the vehicle's traveling direction is a red light, the first communication unit receives an arrival response message and a stop status message from the traffic signal system. The first communication unit transmits a stop state response message and a pilot signal for positioning through a traffic signal system. The first communication unit receives a vehicle location message estimated using arrival times and signal strengths of pilot signals by a plurality of traffic lights installed at different locations in an intersection.

In the stopped state, the second communication unit of the traffic signal system receives an arrival message from the traffic signal system. When the traffic signal for the direction of travel of the vehicle is a red light, the second communication unit transmits an arrival response message and a stop status message to the vehicle. The second communication unit receives a stop state response message and a pilot signal for positioning from the vehicle. The second processing unit estimates the location of the vehicle using the arrival time and signal strength of the pilot signal by a plurality of traffic lights installed at different locations in the intersection. The second communication unit transmits a vehicle location message about the location of the vehicle to the vehicle.

5 is a diagram illustrating messages transmitted and received between a vehicle and a traffic signal system in a starting state according to embodiments of the present invention.

Vehicle departure is divided into cases where a signal is required (go straight and turn left in Korea) and case where a signal is not required (turn right in Korea). If a signal is required, when a traffic signal turns green, the traffic light sends an SC-B message (confirming that it is in B state) to vehicles traveling in that direction. After receiving the SC-B message and starting acceleration, the vehicle transmits the RS along with the SC-B ACK message (response to SC-B) after a certain time has elapsed. Under the condition that the traffic signal system sends the SC-B message and the vehicle sends the SC-B ACK message after a preset waiting time, the traffic signal system determines that the vehicle's moving direction is a straight path and a left turn path (lane). can The traffic light receiving the SC-B ACK estimates the vehicle's moving direction by estimating the location of the vehicle using RS.

Using the estimated moving direction of the vehicle, hand-off is performed by delivering a VHA message (vehicle entry information) to the next intersection where the vehicle will drive and reach. If the vehicle moves in a direction that does not require a signal, the vehicle transmits an SC-B ACK without receiving the SC-B message and performs the same process as above. Under the condition of receiving the SC-B ACK message before transmitting the SC-B message, the traffic signal system may determine that the moving direction of the vehicle is the right turn path (lane).

In a departure state requiring a signal, when the traffic signal for the direction of the vehicle is switched to a green signal, the first communication unit of the vehicle receives a start possible message from the traffic signal system. The first communication unit receives the departure possibility message and transmits a departure status response message and a pilot signal for positioning through the traffic signal system after a predetermined waiting time has elapsed. The traffic light receiving the departure state response message transfers the vehicle entry message to the traffic light at the next intersection in consideration of the location and moving direction of the vehicle estimated using the pilot signal.

In a departure state requiring a signal, when the traffic signal for the vehicle's traveling direction is switched to a green signal, the second communication unit of the traffic signal system transmits a departure possible message to the vehicle. The second communication unit receives a departure state response message and a pilot signal for positioning from the vehicle. The second processing unit estimates the position and direction of movement of the vehicle using the pilot signal. The second communication unit transfers the vehicle entry message to the traffic light of the next intersection.

In a departure state in which a signal is not required, the first communication unit of the vehicle transmits a departure state response message and a pilot signal for positioning to the traffic signal system without considering the traffic signal for the driving direction of the vehicle. The traffic light receiving the departure state response message transfers the vehicle entry message to the traffic light at the next intersection in consideration of the location and moving direction of the vehicle estimated using the pilot signal.

In a departure state in which a signal is not required, the second communication unit of the traffic signal system receives a departure state response message and a pilot signal for positioning from the vehicle before transmitting a departure possibility message to the vehicle. The second processing unit estimates the position and direction of movement of the vehicle using the pilot signal. The second communication unit transfers the vehicle entry message to the traffic light of the next intersection.

6 is a diagram illustrating messages transmitted and received in a moving state between a vehicle and a traffic signal system according to embodiments of the present invention.

The vehicle periodically transmits ARV messages. The traffic light at the intersection receives the ARV message and confirms that the vehicle is entering. Check traffic signals in the direction the vehicle is traveling. When the traffic signal for the vehicle's traveling direction is a green signal, the traffic light transmits an ARV ACK message and an SC-C message (confirming that it is in C state) to the vehicle. After receiving ARV ACK and SC-C while moving, the vehicle transmits SC-C ACK message (response to SC-C) and RS. The traffic light estimates the vehicle's moving direction through RS, and based on this, delivers VHA to the intersection where the vehicle is heading. At the same time, the LOC message is transmitted to the vehicle by correcting and updating the location information of the vehicle using the RS and the moving speed and direction of the vehicle. When a traffic signal is changed to a red light when a vehicle enters an intersection, it switches to the process of state A and executes the corresponding process.

In the moving state, the first communication unit of the vehicle periodically transmits an arrival message to the traffic signal system. When the traffic signal for the direction of travel of the vehicle is a green signal, the first communication unit receives an arrival response message and a movement status message from the traffic signal system. The first communication unit transmits a movement state response message and a pilot signal for positioning through a traffic signal system. The traffic light receiving the movement state response message transfers the vehicle entry message to the traffic light at the next intersection in consideration of the vehicle's location and moving direction estimated using the pilot signal. The traffic light receiving the moving state response message receives the vehicle location message estimated using the pilot signal, the moving speed and the moving direction of the vehicle.

In the mobile state, the second communication unit of the traffic signal system receives an arrival message from the vehicle. When the traffic signal for the driving direction of the vehicle is a green light, the second communication unit transmits an arrival response message and a movement status message to the vehicle. The second communication unit receives a movement state response message and a pilot signal for positioning from the vehicle. The second processing unit estimates the position and direction of movement of the vehicle using the pilot signal. The second communication unit transfers the vehicle entry message to the traffic light of the next intersection. The second processing unit estimates the position of the vehicle using the pilot signal, the moving speed and the moving direction of the vehicle. The second communication unit transmits a vehicle location message about the location of the vehicle to the vehicle.

A vehicle and traffic signal system may include at least one processor, a computer readable storage medium, and a communication bus.

The processor may control the operation of vehicles and traffic signal systems. For example, a processor may execute one or more programs stored on a computer readable storage medium. The one or more programs may include one or more computer executable instructions, which when executed by a processor may cause vehicles and traffic signal systems to perform operations in accordance with an illustrative embodiment.

A computer readable storage medium is configured to store computer executable instructions or program code, program data and/or other suitable form of information. A program stored on a computer readable storage medium includes a set of instructions executable by a processor. In one embodiment, the computer readable storage medium includes memory (volatile memory such as random access memory, non-volatile memory, or a suitable combination thereof), one or more magnetic disk storage devices, optical disk storage devices, flash memory devices. , other forms of storage media capable of storing desired information and accessed by vehicles and traffic signal systems, or suitable combinations thereof.

Communication buses interconnect various other components of vehicles and traffic signal systems, including processors and computer readable storage media.

Vehicles and traffic signal systems may also include one or more input/output interfaces and one or more communication interfaces that provide interfaces for one or more input/output devices. An input/output interface and a communication interface are connected to the communication bus. The input/output device may be connected to other components of the vehicle and traffic signal system via the input/output interface.

The vehicle and traffic signal system may be implemented in a logic circuit by hardware, firmware, software, or a combination thereof, or may be implemented using a general-purpose or special-purpose computer. The device may be implemented using a hardwired device, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or the like. Also, the device may be implemented as a System on Chip (SoC) including one or more processors and controllers.

The vehicle and traffic signal system may be installed in a computing device or server equipped with hardware elements in the form of software, hardware, or a combination thereof. A computing device or server includes all or part of a communication device such as a communication modem for communicating with various devices or wired/wireless communication networks, a memory for storing data for executing a program, and a microprocessor for executing calculations and commands by executing a program. It can mean a variety of devices, including

In FIGS. 4 to 6, it is described that each process is sequentially executed, but this is merely an example, and a person skilled in the art will refer to FIGS. 4 to 6 without departing from the essential characteristics of the embodiment of the present invention. Various modifications and variations may be applied by changing the order described, executing one or more processes in parallel, or adding another process.

Operations according to the present embodiments may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer readable medium. Computer readable medium refers to any medium that participates in providing instructions to a processor for execution. A computer readable medium may include program instructions, data files, data structures, or combinations thereof. For example, there may be a magnetic medium, an optical recording medium, a memory, and the like. The computer program may be distributed over networked computer systems so that computer readable codes are stored and executed in a distributed manner. Functional programs, codes, and code segments for implementing this embodiment may be easily inferred by programmers in the art to which this embodiment belongs.

These embodiments are for explaining the technical idea of this embodiment, and the scope of the technical idea of this embodiment is not limited by these embodiments. The scope of protection of this embodiment should be construed according to the claims below, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of rights of this embodiment.

Claims (10)

in the vehicle,
A first communication unit that transmits and receives messages to and from the traffic signal system;
It is connected to the first communication unit, divides the driving state of the vehicle into a stop state, a departure state, and a moving state, and transmits and receives messages to and from the traffic signal system according to the stop state, the departure state, and the moving state. a first processing unit that processes differently; and
A moving device connected to the first processing unit and moving the vehicle;
The traffic signal system includes a plurality of traffic lights installed at different locations at an intersection,
In the stopped state,
The first communication unit periodically transmits an arrival message through the traffic signal system,
When the traffic signal for the driving direction of the vehicle is a red light, the first communication unit receives an arrival response message and a stop status message from the traffic signal system;
The first communication unit transmits a stop state response message and a pilot signal for positioning through the traffic signal system;
The vehicle, characterized in that the first communication unit receives a vehicle location message estimated using the arrival time and signal strength of the pilot signal by a plurality of traffic lights installed at different locations in the intersection. delete According to claim 1,
The traffic signal system includes traffic lights installed at a plurality of adjacent intersections,
In the starting state,
When the traffic signal for the driving direction of the vehicle is switched to a green signal, the first communication unit receives a departure possibility message from the traffic signal system;
The first communication unit transmits a departure state response message and a pilot signal for positioning to the traffic signal system after a predetermined waiting time has elapsed after receiving the departure possibility message,
The traffic light receiving the departure state response message transfers the vehicle entry message to the traffic light of the next intersection in consideration of the location and moving direction of the vehicle estimated using the pilot signal. According to claim 1,
The traffic signal system includes traffic lights installed at a plurality of adjacent intersections,
In the starting state,
Without considering the traffic signal for the direction of travel of the vehicle,
The first communication unit transmits a departure state response message and a pilot signal for positioning through the traffic signal system,
The traffic light receiving the departure state response message transfers the vehicle entry message to the traffic light at the next intersection in consideration of the location and moving direction of the vehicle estimated using the pilot signal. According to claim 1,
The traffic signal system includes traffic lights installed at a plurality of adjacent intersections,
In the moving state,
The first communication unit periodically transmits an arrival message through the traffic signal system,
When the traffic signal for the direction of travel of the vehicle is a green signal, the first communication unit receives an arrival response message and a movement status message from the traffic signal system;
The first communication unit transmits a movement state response message and a pilot signal for positioning through the traffic signal system,
The traffic light receiving the movement state response message transmits a vehicle entry message to the traffic light at the next intersection in consideration of the location and moving direction of the vehicle estimated using the pilot signal;
The traffic light receiving the moving state response message receives a vehicle location message estimated using the pilot signal, the moving speed and the moving direction of the vehicle. In the traffic signal system,
A second communication unit for transmitting and receiving messages to and from the vehicle; and
A second processing unit connected to the second communication unit and processing messages transmitted and received with the vehicle differently according to driving conditions of the vehicle divided into a stop state, a departure state, and a moving state;
The traffic signal system includes a plurality of traffic lights installed at different locations at an intersection,
In the stopped state,
The second communication unit receives an arrival message from the traffic signal system,
When the traffic signal for the direction of travel of the vehicle is a red light, the second communication unit transmits an arrival response message and a stop status message to the vehicle;
The second communication unit receives a stop state response message and a pilot signal for positioning from the vehicle,
The second processing unit estimates the location of the vehicle using the arrival time and signal strength of the pilot signal by a plurality of traffic lights installed at different locations in the intersection,
The traffic signal system of claim 1 , wherein the second communication unit transmits a vehicle location message about the location of the vehicle to the vehicle. delete According to claim 6,
The traffic signal system includes traffic lights installed at a plurality of adjacent intersections,
In the starting state,
When the traffic signal for the driving direction of the vehicle is switched to a green light, the second communication unit transmits a departure enable message to the vehicle;
The second communication unit receives a departure state response message and a pilot signal for positioning from the vehicle,
The traffic signal system of claim 1 , wherein the second processing unit estimates the location and moving direction of the vehicle using the pilot signal, and the second communication unit transfers a vehicle entry message to a traffic light at a next intersection. According to claim 6,
The traffic signal system includes traffic lights installed at a plurality of adjacent intersections,
In the starting state,
The second communication unit receives a departure status response message and a pilot signal for positioning from the vehicle before transmitting a departure possibility message to the vehicle,
The traffic signal system of claim 1 , wherein the second processing unit estimates the location and moving direction of the vehicle using the pilot signal, and the second communication unit transmits a vehicle entry message to a traffic light at a next intersection. According to claim 6,
The traffic signal system includes traffic lights installed at a plurality of adjacent intersections,
In the moving state,
The second communication unit receives an arrival message from the vehicle,
When the traffic signal for the driving direction of the vehicle is a green light, the second communication unit transmits an arrival response message and a movement status message to the vehicle;
The second communication unit receives a movement state response message and a pilot signal for positioning from the vehicle,
The second processing unit estimates the location and moving direction of the vehicle using the pilot signal, the second communication unit transmits a vehicle entry message to the traffic light of the next intersection,
The second processing unit estimates the location of the vehicle using the pilot signal, the moving speed and the moving direction of the vehicle, and the second communication unit transmits a vehicle location message about the location of the vehicle to the vehicle. traffic signal system.

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