JP2003288681A - Road-vehicle communication system by narrow-band radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a frequency selecting and direction detection method for on-vehicle device by a communication method for performing a drive support system by DSRC. <P>SOLUTION: This road-vehicle communication system for performing a communication with a traveling vehicle comprises an advance base station 1 having the function of transmitting broadcast data provided from a road-side processor 3 and adding frequency information and base station number information with which an on-vehicle terminal selects the next base station to the head of the broadcast data, the advance base station performing a report at a preferential frequency of narrow-band radio communication; the next base station 3 having the function of adding base station number information with which the on- vehicle terminal performs a wrong detection with the information of the advance base station to the head of the broadcast data, the next base station performing communication at the frequency reported in the advance base station to provide information; and the on-vehicle terminal 4 having a frequency selecting function and a next base station information waiting function. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a short range wireless communication system (DSRC, Dedicated Short Range Communications).
In the road-to-vehicle communication system according to the above, the present invention relates to a system that supports a roadside system using a frequency and performs a direction detection method composed of a pre-base station and a next base station.

[0002]

2. Description of the Related Art An example of use of a conventional DSRC system is an automatic toll collection system (ETC). It communicates with vehicles passing through the gate and collects fees, and the direction of vehicles passing through the wireless zone is limited to one direction. Further, the frequencies used are two waves of the priority frequency, and the in-vehicle device only needs to constantly detect the two waves, and can establish synchronization in the wireless zone and establish communication in a short time. It was

The current DSRC system is considered to provide various services including private use, and uses a plurality of frequencies including the priority frequency used for ETC,
It is considered to increase the frequency reuse efficiency and effectively use the frequency resource by configuring the narrow zone, and it is required to transmit a large amount of data.
A travel support system is considered as a service using this DSRC system. In the driving support system,
It is necessary to detect the traveling direction of the vehicle and provide information corresponding to the traveling direction.

As a method of detecting a direction in a road-vehicle communication system between a base station installed on the side of a road and a traveling vehicle,
It is possible to provide only the information suitable for the direction to the vehicle side by combining the advance base station and the next base station. This can be achieved by realizing a wireless zone in only one direction of the road, but due to the characteristics of radio waves, the wireless zone cannot be set in one lane only, and the wireless zone leaks to the opposite lane side. Therefore, the in-vehicle wireless device is notified of the own base station number, the next base station number, etc. from the advance base station, and the next base station is also notified of the own base station number and the advance base station number, so that the information suitable for the direction of the vehicle can be obtained. However, no specific communication system of the vehicle-mounted device for the direction detection in the driving assistance system when a plurality of frequencies according to the current DSRC is used has been provided.

When a roadside device is installed on a highway, the zone has a length of only about 30 m in narrow area communication, and the time for a vehicle to pass through this zone is 100 km (28 m / s).
Then, it takes about 1 second. Also, in order to avoid interference in each zone, it is considered to use multiple carriers to avoid interference in adjacent zones.Therefore, there are multiple frequencies used in the system and communication when entering that zone. Is
If the time from carrier detection to establishment of communication is long, the amount of data communication in one zone is limited. DSR
Since the C system uses a plurality of frequencies, if all the frequencies are sequentially detected, it takes a long time to establish communication at each base station.

In addition, in the on-vehicle device of the DSRC system,
Since it is necessary to establish synchronization for the two waves of the priority frequencies in a short time, the time taken to detect other frequencies should be as short as possible.
There is a need for a frequency selection method that provides real-time information while increasing the amount of information that can be communicated by lengthening the communication time of user information.

At the same time as this problem, there is a need for a communication system for a vehicle-mounted terminal having a function of performing conventional direction detection and performing erroneous detection so as not to provide information on a different direction to the vehicle.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a road-vehicle communication system based on a short-range wireless communication system capable of solving the above-mentioned conventional problems.

[0009]

In order to achieve the above object, the invention as set forth in claim 1 is a road-vehicle communication system for communicating with a traveling vehicle, wherein broadcast data provided from a roadside processing device is used. At the beginning of the broadcast data while sending,
The in-vehicle terminal has a function of adding frequency information and base station number information for selecting the next base station, and a pre-base station that notifies at the priority frequency of the short-range wireless communication, and from the roadside processing device like the pre-base station. The broadcast data provided is divided and transmitted, and at the beginning of the broadcast data, the in-vehicle terminal has a function of adding base station number information that makes a false detection with the information of the advance base station. When receiving the prior base station information by waiting for reception at the priority frequency with the next base station that provides information that communicates at the specified frequency, the next base station number information that is provided is retained and notified by the prior base station. It has a frequency selection function that waits for the frequency of the next base station for a period of time, and when it is received by the next base station, the next base station information at the previous base station at the beginning of the broadcast data and the next base station received. According to the base station information at the station Performs error detection, if correct,
It is characterized by being configured with an in-vehicle terminal equipped with a next base station information waiting function that validates broadcast data and operates the frequency selection function if it is incorrect.

According to a second aspect of the present invention, in the first aspect, when the vehicle-mounted terminal receives the broadcast information broadcast from the advance base station, the frequency for waiting for reception of the next base station even in the communication area. The information from the advance base station is changed to the minimum reception, depending on the timing (position),
It is characterized by having a function that can be used as a reference point of the vehicle position.

According to the invention of claim 3, in claim 1 or 2, the pre-base station and the next base station have a function of adding the information of the number of times of reception to the information added to the data from the roadside processing device. The in-vehicle terminal receives information from the advance base station and the next base station, and then the advance base station receives the broadcast data for the number of times of reception, and then sets the frequency of the next base station and waits for reception. However, it is characterized in that it has a function of ending the processing and returning to the initial frequency waiting state after the broadcast data for the reception frequency information is normally received.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the accompanying drawings.

[First Embodiment] FIG. 1 is a processing flowchart of an in-vehicle terminal, FIG. 2 is a block diagram of a wireless communication frame,
FIG. 3 is a lateral example of road-vehicle communication, and FIG. 4 is a configuration example of an in-vehicle terminal device. As shown in FIG. 3, the pre-base station 1 adds the base station information for selecting the next base station 3 to the broadcast data from the roadside processing device 2 and transmits it at the frequency of fl or f2 of the priority frequency. Details of the wireless frame being transmitted and the information added by the base station are shown in the detailed data example of the broadcast slot in FIG.

Since the frequency of the advance base station 1 is fixed to the priority frequency, the vehicle-mounted terminal 4 scans two waves.
Upon entering the communication area of the base station 1 in advance, the level of the radio wave and the establishment of synchronization are detected. Receive data. For the received data, as shown in FIG. 2, the base station information header at the head is referred to. By adding the base station information to the head, the correctness determination process is performed quickly.

In the case of the advance base station 1, the information for determining the next base station is acquired and held in the storage unit, and the broadcast data from the roadside processing unit 2 is transferred to the upper processing unit. When the reception interruption in the advance base station 1 is detected, it is determined that the communication area of the advance base station 1 has passed, and based on the frequency information (fx) and the waiting time information (t1) of the next base station 3 which is held. Then, frequency selection processing is performed, and one wave of the designated frequency (fx) is scanned for t1 time. Let t1 be the time determined from the position of the base station 1 to the next base station 3 and the speed of the vehicle under normal traffic conditions. In the t1 time, the data which has entered the communication area of the next base station 3 is established by one-wave scan. As in the case of the advance base station 1, the next base station 3 transmits broadcast data to which a base station information header for erroneous detection determination is added. The advance base station number of this data is compared with the held advance base station number, and if correct, the data from the roadside processing device 2 is transferred to the host device. In the case of the next base station 3 on the opposite lane using the same frequency, the vehicle side can acquire information that can be determined by this erroneous detection and that matches the traveling direction. If the reception is cut off after passing through the communication area, it returns to the initial state and returns to the two-wave scan waiting for the advance base station.

If the next base station 3 cannot be reached within t1 hours,
It is possible that the speed is slow or the road is off the road. In this case, the frequency fx and the priority frequency fl held by the base station 1 in advance are
Frequency selection processing of frequency scan is performed with 3 waves of f2.
After that, when the communication area enters f3, the above-mentioned operation is performed. Further, when the signal is received at the frequency of fl or f2 of the priority frequency, a new advance base station 1 or another service may be considered, and therefore the process returns to the first process. By the above operation, when a plurality of frequencies are used, the communication establishment time of each base station can be shortened and the base station can be erroneously detected.

[Second Embodiment] FIG. 5 is a processing flowchart of the vehicle-mounted terminal, and FIG. 6 is a configuration example of road-to-vehicle communication.
In the vehicle-mounted terminal of the first embodiment, when the broadcast information broadcast from the advance base station 1 is received, the frequency is switched to the waiting frequency for the next base station even in the communication area. This minimizes reception from pre-base station 1,
Depending on the timing (position), it is provided with a function that can be used as a reference point of the vehicle position.

The operation will be described. Since the frequency of the advance base station 1 is fixed to the priority frequency, the vehicle-mounted terminal 4 scans two waves. Upon entering the communication area of the base station 1 in advance, the level of the radio wave is detected, the establishment of synchronization is detected, and the data is received. For the received data, as shown in FIG. 2, the base station information header at the head is referred to. By adding the base station information to the head, the correctness determination process is performed quickly.

In the case of the advance base station 1, the information for determining the next base station is acquired and stored in the storage unit, and the broadcast data from the roadside processing unit 2 is transferred to the upper processing unit, and the next base station 3 is held. Frequency selection processing is performed based on the frequency information (fx) and waiting time information (t1) of the specified frequency (fx)
It shifts to the one-wave scan. By this operation, the host processor can fix the reference point (position) at the timing of the broadcast data in the advance base station 1.

[Third Embodiment] FIG. 7 is a processing flowchart of the vehicle-mounted terminal, and FIG. 8 is a configuration diagram of a wireless communication frame. In the advance base station 1 of the first embodiment and the next base station 3 for providing information, a base having a function of adding the information of the number of times of reception to the information added to the data from the roadside processing device 2 Based on the stations 1 and 3 and the information thereof, the advance base station 1 sets the frequency of the next base station and waits for reception after receiving the broadcast data for the reception number information, and the next base station 3 also receives the reception number information. The vehicle-mounted terminal 4 is provided with a function of ending the processing and returning to the initial frequency waiting state after the broadcast data of (1) is normally received. This allows you to specify the number of times the broadcast data needs to be sent on the roadside,
Further, on the side of the in-vehicle terminal 4, it becomes possible to confirm whether the reception is normally completed.

The operation will be described. Since the frequency of the advance base station 1 is fixed to the priority frequency, the vehicle-mounted terminal 4 scans two waves. Upon entering the communication area of the base station 1 in advance, the level of the radio wave and the establishment of synchronization are detected. Receive data. For the received data, as shown in FIG. 8, the base station information header at the head is referred to. In the case of the advance base station 1, the information for determining the next base station is acquired, and the broadcast data reception count (n) is held in the storage unit.

The broadcast data from the roadside processor 2 is transferred to the upper processor and the number of times is counted. When the prior base station 1 cuts off the reception or receives the broadcast data n times, the next base station 3 which has held the communication area of the advance base station 1
Frequency selection processing is performed based on the frequency information (fx) and the waiting time information (t1). After that, the same processing as in the first embodiment is performed.

At the next base station 3, like the advance base station 1,
Broadcast data to which a base station information header for erroneous detection determination is added is transmitted. In this case as well, the broadcast data reception count (n) is held. If erroneous detection processing is performed and the data is correct, the data from the roadside processing device 2 is transferred to the host device, and the number of times of transfer is counted at this time. When the broadcast data is received n times or the reception is cut off after passing through the communication area, the initial state is returned to the two-wave scan waiting for the advance base station. By making it possible to specify the number of times of receiving the broadcast data on the roadside, it is possible to easily change to the second embodiment. Further, depending on the service, the number of times of reception can be fixed, and it becomes possible for the receiving side to judge whether normal reception is completed.

[0024]

As described above, the present invention is a narrow-range wireless communication system for road-to-vehicle communication utilizing a plurality of frequencies, and in a service for communicating with a vehicle traveling at high speed, the traveling direction is changed. It can detect and establish communication in a short time to increase the amount of information transfer in the communication area.
There is an excellent effect that it is possible to easily perform the frequency selection method by which software other than the ETC service realized by SRC can be simultaneously received by the software processing of the vehicle-mounted terminal.

[Brief description of drawings]

FIG. 1 is a processing flowchart of an in-vehicle terminal showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a wireless communication frame of the above, (A) shows a wireless section, and (B) shows a detailed data example of a broadcast slot.

FIG. 3 is a configuration example of road-to-vehicle communication in the above.

FIG. 4 is a configuration example of the vehicle-mounted terminal device of the above.

FIG. 5 is a processing flowchart of the vehicle-mounted terminal according to the second embodiment.

FIG. 6 is an example of the configuration of road-vehicle communication in the above.

FIG. 7 is a processing flowchart of the vehicle-mounted terminal according to the third embodiment.

FIG. 8 is a configuration diagram of the above-described non-repeating communication frame, in which (A) shows a wireless section and (B) shows an example of detailed data of a broadcast slot.

[Explanation of symbols]

1 Advance base station 2 Roadside processing equipment Tertiary base station 4 In-vehicle terminal

Claims (3)

[Claims] 1. A road-vehicle communication system for communicating with a traveling vehicle, for transmitting broadcast data provided from a roadside processing device, and for an in-vehicle terminal to select a next base station at the beginning of the broadcast data. Of the advance base station which has a function of adding the frequency information and the base station number information, and which broadcasts at the priority frequency of the narrow area wireless communication, and the broadcast data provided from the roadside processing device like the advance base station is divided. It is equipped with a function to add the base station number information to the head of the broadcast data, which transmits the broadcast data and makes an erroneous detection with the information of the advance base station, and provides the information to communicate at the frequency notified by the advance base station. When waiting for reception at the priority frequency with the next base station to be performed and receiving the advance base station information, the next base station number information provided is held and the next base station is notified for the time notified by the advance base station. Waiting for frequency If the next base station is equipped with a frequency selection function that does this, it will make an erroneous detection based on the next base station information from the previous base station at the beginning of the broadcast data and the received base station information from the next base station. , A road-to-vehicle communication system based on the short-range wireless communication system, which is composed of an on-vehicle terminal equipped with a next base station information waiting function that, if correct, validates broadcast data and, if incorrect, operates a frequency selection function. 2. When the vehicle-mounted terminal receives the broadcast information broadcast from the advance base station, it switches to the frequency for waiting for the next base station reception even in the communication area, The road-to-vehicle communication system according to the short-range wireless communication system according to claim 1, further comprising a function of limiting the amount of information received to a minimum and using the timing (position) as a reference point of a vehicle position. 3. The advance base station and the next base station have a function of adding information on the number of times of reception to the information added to the data from the roadside processing device, and the vehicle-mounted terminal has the advance base station and the next base station. After receiving the broadcast data for the reception count information, the advance base station sets the frequency of the next base station and waits for the reception, and the next base station also normalizes the broadcast data for the reception count information. 3. The device according to claim 1, further comprising a function of ending the processing after receiving and returning to the initial frequency waiting state.
A road-vehicle communication system based on the described short-range wireless communication system.