JPH0585080B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a road-to-vehicle communication method performed between a roadside beacon placed at a predetermined position on a road network and a vehicle traveling on the road. be.

<Prior art> A road-to-vehicle communication method using a roadside beacon emits beacon radio waves indicating the position data of the roadside antenna from a roadside antenna to a narrow range on the road network, and calibrates the position of the navigation device mounted on the vehicle. The original purpose was to do so.

However, in order to make effective use of roadside beacons, not only vehicles equipped with navigation devices but also vehicles without navigation devices are equipped with various types of information corresponding to the direction of travel, such as roadside antennas. Traffic information such as road congestion, construction, and other road usage conditions around the location, residential layouts around the location where the roadside antenna is installed, detailed map information including individual names, and information on where the roadside antenna is installed. There is a need to provide road map information covering a fairly wide range of areas, including the locations where the roads are located. In other words, the traffic information enables smooth operation, and
This is to make it easier to reach the destination using map information.

As shown in FIG. 6A, a method for providing the above-mentioned various information from a roadside device to a vehicle is as shown in FIG. 6A.
A method of emitting radio waves carrying information about the front of both the upper and lower lanes c1 and c2 with the directionality directed to include c2 (hereinafter referred to as a shared beacon);
And as shown in Figure 6B, one-sided lanes c1, c2
Roadside antennas a1 and a2 are installed at each roadside antenna, and the radiation areas b1 and b2 of each roadside antenna a1 and a2 are directed so as to cover their respective lanes, and radio waves carrying information about the area ahead in the direction of travel of the lane are transmitted. There are two types of radiating methods (hereinafter referred to as one-sided beacons).

If the shared beacon is used, it is necessary to supply a direction identification signal to the vehicle in place of the direction sensor for vehicles not equipped with a navigation device. The shared beacon transmits information for both the up and down lanes, and vehicles without a direction sensor cannot determine the direction of travel on their own, so the 180
This is because there is a possibility that different information may be taken in.

With the one-sided beacon mentioned above, it emits radio waves containing information about the direction ahead of the lane in question, so there is no need for the vehicle to determine the direction of travel, and it is compatible with vehicles that are not equipped with a navigation device. It is thought that this information can be imported. However, with single-sided beacons, it is difficult to separate the radiation area in the center of the driving lane.
There is a problem in that radio waves leak into the opposite lane and vehicles traveling in the opposite lane receive information from the opposite direction, making it necessary to supply direction identification signals to vehicles in the same way as shared beacons. Additionally, roadside devices twice as many as shared beacons are required.

From the above point of view, the applicant of the present application
No. 45616 provides a roadside beacon system mainly using shared beacons.

The roadside beacon system related to patent application No. 63-45616 is
The roadside antenna is configured with a pair of two antenna elements with different main radiation directions, and the first modulated wave signal is modulated based on a transmission data frame consisting of various data such as position data, traffic information, road map information, etc. A second modulated wave signal which is amplitude-modulated by a modulating signal that is synchronized with the transmission data frame and set to have opposite phases to each other is transmitted to the roadside so that the first modulated wave signal is in the same phase. The phase of the amplitude modulation component radiated from the antenna and demodulated by the in-vehicle receiver is compared with the phase of the transmitted data frame, and the vehicle's It is designed to determine the direction of travel. The clever method described above allows a vehicle not equipped with a navigation device to determine the direction of travel of the vehicle and to capture information ahead in the direction of travel.

<Problem to be solved by the invention> However, from the viewpoint that it is preferable to emit radio waves in as narrow a range as possible in consideration of radio interference, etc., shared beacons are adopted for narrow roads with about one lane on each side. However, for wide roads with two lanes on each side, it is being considered to use beacons on one side to radiate radio waves in as narrow a range as possible, and to transmit and receive radio waves between the central station and vehicles via roadside antennas. I started thinking about having them do this as well.

In order to use both beacons on one side and both sides and also transmit and receive data between the central station and the vehicle via the roadside antenna, while the vehicle is within the communication range of the roadside antenna, It is necessary to determine whether the signal should be received or not, and to transmit a signal for recognizing the own vehicle to the roadside antenna corresponding to the direction of travel. Note that the roadside antenna communication area substantially coincides with the radiation area.

However, by applying the roadside beacon method related to the applicant's earlier application to the shared beacon, it is possible to determine the direction of travel on the vehicle side, so it is possible to determine whether the signal should be received or not. Because it is used in conjunction with a beacon, it is not possible to quickly determine whether the roadside antenna should transmit from the vehicle.

In addition, if the roadside beacon method related to the applicant's earlier application is applied as is to a one-sided beacon with a narrow communication area, the vehicle side may perform phase comparison with the amplitude modulation component after recovering frame synchronization. Since the direction of travel is determined based on the direction of travel, it takes some time to synchronize. Therefore, in road-to-vehicle communication using a one-sided beacon with a narrow communication area, there is a risk that the vehicle has already left the communication area by the time the direction of travel is determined.

This invention was made in view of the above problems, and enables a vehicle to quickly determine whether or not to acquire data from a roadside beacon while in a communication area. It is an object of the present invention to provide a road-to-vehicle communication method that makes it possible to quickly determine whether or not a signal for recognizing a vehicle should be transmitted to a roadside beacon when data is acquired.

<Means for Solving the Problems> The present invention is a communication method between a roadside beacon placed at a predetermined position on a road network and a vehicle traveling on a road, which comprises: Depending on the type of road, a one-sided beacon that emits various data corresponding to the direction of travel of one lane of the road, or a beacon that emits various data corresponding to the direction of travel of both lanes of the road, or a beacon that emits various data corresponding to the direction of travel of both lanes of the road. Each roadside beacon shall be equipped with at least two antenna elements with different main radiation directions, and whether the roadside beacon is a single-sided beacon or a shared beacon. The beacon type data indicating whether the beacon is a beacon and the above-mentioned various data are added to the signal using the first modulation method, the signal is divided into two, and the two divided signals are subjected to amplitude modulation with mutually opposite phases. 2 modulation signals are generated, the second modulation signals are fed to the two antenna elements of the roadside beacon so that the first modulation components are in phase, and on the vehicle side, the second modulation signals radiated from the roadside beacon are receive, extract the amplitude modulation signal component from the second modulation signal, demodulate the signal of the first modulation method to recognize the type of roadside beacon, and extract the demodulated signal of the first modulation method and the extracted amplitude modulation component. The present invention is characterized by comparing the phase with the first modulation method and determining whether or not to import the data carried on the demodulated signal of the first modulation method based on the phase comparison result and the type of the roadside beacon. It is something to do.

In addition to the above-mentioned configuration, the present invention also provides that, when it is determined that the signal should be captured, after capturing the signal,
Furthermore, the present invention is characterized in that predetermined data is transmitted to the roadside beacon.

<Operation> With the above configuration, data corresponding to the type of roadside beacon and a signal for determining the traveling direction (phase difference between the first modulation component and the amplitude modulation component) are transmitted from the roadside beacon to the in-vehicle receiver, etc. Therefore, in-vehicle receivers, etc. can distinguish roadside beacons based on data corresponding to the type of roadside beacon, and by comparing the type of roadside beacon and the determination result of the direction of travel, It is possible to quickly determine whether or not to import data from.

To explain in more detail, the roadside beacon bisects the signal of the first modulation method carrying data corresponding to the type of roadside beacon, that is, data for distinguishing whether it is a shared beacon or a one-sided beacon. By subjecting the signals to mutually opposite phase amplitude modulation, a second modulated signal carrying position data is radiated in two directions from the two antenna elements. However, which main radiation direction should be in positive phase or in negative phase should be unified. For example, in a shared beacon, the amplitude is modulated so that the signal goes from normal phase to anti-phase as it progresses from upstream to downstream. Furthermore, in a one-sided beacon, the amplitude is modulated from normal phase to reverse phase according to the traveling direction.

On the vehicle side, first, the phase of the demodulated amplitude modulation component and the phase of the first modulation method signal are compared, and it is determined whether the phase of the amplitude modulation component is in phase with respect to the signal of the first modulation method or in reverse phase. do. Next, the signal of the first modulation method is demodulated to recognize whether the type of roadside beacon is a shared beacon or a one-sided beacon. Further, based on the relationship between the type and phase of the beacon, it is determined whether the data obtained by demodulating the signal of the first signaling system is the data to be captured.

For example, if the beacon is on one side and the phase is positive, the received data is captured, and if the beacon is on one side and the phase is reversed, the received data is not captured.

In addition, in the case of a single-sided beacon, data is received once regardless of whether the phase is positive or negative, and then progresses from upstream to downstream depending on whether the phase changes from positive phase to negative phase or from negative phase to positive phase. It determines whether the data is progressing from down to up, and based on the results, it selects whether to import or discard data.

Furthermore, in the invention set forth in claim 2, in the invention set forth in claim 1, when it is determined that data should be captured, a predetermined signal is transmitted from the vehicle side toward the roadside beacon, so that the traveling direction A predetermined signal can be transmitted to a roadside beacon that supports the following.

<Example> An example of the present invention will be described in detail below with reference to the drawings. The arrangement of the roadside device (roadside beacon) is as shown in FIG. 6 already shown.

FIG. 1A is a configuration block diagram of a roadside device according to an embodiment of the present invention, and FIG. 2 is a waveform diagram schematically representing the signals in FIG. 1A.

In FIG. 1A, a data transmitter 11 serially transmits position, direction (direction of the road), road information, traffic information (in the case of a two-way communication roadside beacon system, this includes data such as messages and faxes), etc. This is a component that converts it into a code string and outputs it.

The signal sent from this data transmitter 11 is
As shown in "A: Transmission data frame" in Figure 2, the shared beacon frame is intermittently and repeatedly transmitted in frame units, and includes a header, common data, direct correspondence data, and reverse phase correspondence data. There is. Further, the frame of the one-sided beacon excludes data corresponding to opposite phases. The header arranged at the beginning of the frame is provided with functions necessary for communication, such as beacon distinction for distinguishing whether it is a shared beacon or a one-sided beacon, code element synchronization, frame synchronization, etc. In addition, in this embodiment, the transmission rate of the transmission data frame is
It is set to 512kbps.

A transmission data frame sent out from data transmitter 11 is provided to data modulator 12 .

The data modulator 12 modulates a carrier wave fc (a carrier wave whose center frequency is fc) provided from the carrier wave generator 14 with a transmission data frame to generate a first modulated wave signal. The modulation method in the data modulator 12 may be any modulation method, including amplitude modulation, frequency modulation, phase modulation, etc.

In this example, PSK (phase shift
keying) modulator or ASK (amplitude shift)
keying) modulator is used. In terms of performance,
The data modulator 12 is preferably a PSK modulator, but if cost reduction is desired, an ASK modulator may be used.

The first modulated wave signal generated by data modulator 12 is divided into two parts and applied to amplitude modulators 15 and 16, respectively.

The modulation signal generator 13 generates an amplitude modulation signal fm (a signal whose center frequency is fm).
A synchronization signal given from the data transmitter 11 synchronizes the amplitude modulation signal fm with the transmission data frame. Specifically, in this embodiment, the same clock signal used in the data transmitter 11 is counted down, and
The operation is started in accordance with a synchronization signal from the data transmitter 11.

The frequency fm of the amplitude modulation signal is the carrier wave fc described above.
A frequency that is sufficiently low compared to the data transmission rate is selected. Specifically, in this example
A frequency of about 1kHz is used. The amplitude modulation signal fm synchronized with the transmission data frame outputted from the modulation signal generator 13 is given to the amplitude modulator 15 as it is, and is inverted to the opposite phase by the 180° phase shifter 17 and sent to the amplitude modulator 16. Given.

The amplitude modulator 15 converts the first modulated wave signal provided from the data modulator 12 into the modulated signal generator 13.
The modulation rate of the modulation signal fm is selected to be 0.5 or less so that the first modulation wave signal does not become too small. The signal modulated by the amplitude modulator 15 is "B: second modulated wave signal (positive phase)" in FIG.
The resulting signal is given to the split beam antenna 19 through the demultiplexer 18a.

The amplitude modulator 16 also has the same configuration as the amplitude modulator 15, and converts the first modulated wave signal given from the data modulator 12 into an amplitude modulated signal fm whose phase is reversed by the 180° phase shifter 17. Modulate. As a result,
The output of the amplitude modulator 16 becomes a signal indicated by "C: second modulated wave signal (reverse phase)" in FIG. This second modulated wave signal (reverse phase) is also applied to the split beam antenna 19 through the duplexer 18b. It should be noted that which main radiation direction should be in positive phase or in negative phase should be unified. For example, in a shared beacon, the amplitude is modulated so that the signal goes from normal phase to anti-phase as it progresses from upstream to downstream. Furthermore, in a one-sided beacon, the amplitude is modulated from normal phase to reverse phase according to the traveling direction.

As an example of the spirit beam antenna 19 is shown in FIG. 3, an antenna element 18 having different main radiation directions and receiving directivity
The configuration includes a and 18b. When the antenna 19 is fed with in-phase signals, the radiated signals radiated from each antenna element 19a, 19b become a composite sum, and exhibit a radiated electric field strength as shown in FIG. 4A. Furthermore, when the signal is fed in reverse phase, as shown in FIG. 4B, the intensity of the radiated electric field at the boundary line between different main radiation directions decreases in level rapidly, indicating a spirit beam directivity. still,
The reception directivity matches the electric field strength shown in FIG. 4A.

The receiver 20 on the roadside device side is a component that receives transmission signals from the vehicle side, such as vehicle ID signals, communication permission signals, etc., and transmits them to the central station.

Signals radiated from the roadside device spirit beam antenna 19 are processed by a transmitting/receiving device mounted on a vehicle having the configuration shown in FIG. 1B.

In FIG. 1B, a signal received by an antenna 21 is supplied to a reception amplifier 28 through a branching filter 22, is amplified to a required level by a reception amplifier 23, and is then amplified by a data demodulator 24 and a modulated signal demodulator 2.
given to 5. The data demodulator 24 corresponds to the data modulator 12 (see FIG. 1A) of the roadside device, and is for demodulating the first modulated wave signal to obtain a received data frame. The received data frame demodulated by the data demodulator 24 is provided to the synchronization detector 26.

The synchronization detector 26 detects element synchronization and frame synchronization from the received data frame.
It functions for restoring received data and reproducing modulated signals. Received data such as beacon discrimination data restored by the synchronization detector 26 is provided to a data processing section 27, and the output of the synchronization detector 26 is provided to a modulated signal regenerator 28.

The modulated signal regenerator 28 has the same function as the modulated signal generator 13 (FIG. 1A) of the roadside device,
The modulated signal fm' is regenerated using a frame synchronization signal based on a received data frame and a received data clock. The reproduced modulated signal fm′ is
It is applied to one input terminal of the phase comparator 29.

The modulated signal demodulator 25 described above corresponds to the amplitude modulators 15 and 16 (see FIG. 1A) of the roadside device, and functions to demodulate the second modulated wave signal and extract the amplitude modulated signal fm. . Modulated signal demodulator 2
The modulated signal fm demodulated by the phase comparator 29
is applied to the other input terminal of

The phase comparator 29 compares the phases of the modulated signal fm' regenerated by the modulated signal regenerator 28 and the modulated signal fm demodulated by the modulated signal demodulator 25.
The output is either a positive signal or an inverse binary signal depending on whether the signal fm' and the signal fm are in phase, and is supplied to the data processing section 27.

Modulated signal fm demodulated by modulated signal demodulator 25
is also provided to the level determiner 30. The level determiner 30 uses the spirit beam antenna 19
This detects a sudden level drop that occurs at the boundary line in the main radiation direction (see FIG. 4B), and its output is given to the data processing section 27 as a position pulse.

The data processing unit 27 restores received data such as beacon discrimination data given from the synchronization detector 26, and uses the restored received data and the phase comparator 29.
Forward/reverse signals given from and level judger 3
This component performs processing such as determining the traveling direction, outputting a transmission command signal to the transmitter, and capturing various data corresponding to the traveling direction based on the position pulse from 0. The data processing section 27 is specifically configured with a microcomputer or the like. The output of the data processing section 27 is then given to the display section 31 and displayed so that it can be visually recognized by the driver of the vehicle or the like.

The transmitter 32 is a component that modulates an ID signal, a reception permission signal, etc. according to a transmission command signal given from the data processing section 27, and supplies the modulated wave to the antenna 21 through the duplexer 22.
Note that after communication is permitted, a call can be made with the central office using a predetermined channel.

FIG. 5 is a diagram for explaining the receiving operation of the receiving device shown in FIG. 1B while the vehicle is running.

Next, the operation of the receiving apparatus shown in FIG. 1B will be explained with reference to FIG. 5.

In FIG. 5a, A-B represents the direction of the road, and with respect to this road, the second modulated wave signal is transmitted from the spirit beam antenna 19 of the roadside device to the main radiation beam with the positive phase and the main radiation beam with the negative phase. It is radiated with the spirit beam characteristics of the main radiation beam.

Assuming that a vehicle is traveling on a road in the direction from A to B, a receiving device mounted on the vehicle first enters a positive phase beam emission region and receives a radiation signal. At this time, the signal (second modulated wave signal (positive phase)) received through the duplexer 22 and output from the reception amplifier 23 is a signal with an electric field strength distribution as shown in FIG. 5b. As described above, this signal is demodulated by the data demodulator 24 and supplied to the data processing section 27 via the synchronization detector 26.
Then, the data processing unit 27 determines whether the beacon is a one-sided beacon or a shared beacon based on the beacon discrimination data in the received data provided from the synchronization detector 26. Further, in the synchronization detector 26, the detected synchronization signal is supplied to a modulation signal regenerator 28, where the modulation signal fm' is regenerated, and the modulation signal fm' is regenerated by the modulation signal demodulator 25. is demodulated. Then, the reproduced modulation signal fm' and the demodulated modulation signal fm are sent to the phase comparator 2.
9, the data processing unit 27 determines that the received signal is the second modulated wave signal of positive phase.

Next, the data processing unit 27 compares the type of beacon and the phase of the received signal, and if it is determined that the beacon is on one side and the received signal is in the correct phase, the data processing unit 27 takes in the received data given from the synchronization detector 26, Intersection information, forward traffic information, and other data necessary for traveling in the direction A→B on the road are selected and displayed on the display section 31, and a transmission command signal is commanded to the transmitting section 32. Then, the transmitter 32 switches the duplexer 22 and transmits the ID number, communication permission signal, etc. to the roadside antenna.

If the beacon is on one side and the received signal is of opposite phase, the received data will not be taken in and the transmission command signal will not be output. In other words, this prevents the vehicle from receiving radio waves leaking from the opposite lane.

If it is determined that the beacon is a shared beacon, a transmission command signal is output to the transmitter 32 regardless of whether the received signal is in phase or not, and data acquisition is performed in the main radiation direction of the split beam antenna 19. This is done after detecting a sudden level drop that occurs at the boundary line.

That is, when the vehicle continues to run, the level determiner 3
0, the position where the level suddenly drops as shown in FIG. 5c is detected, and the position pulse shown in FIG. 5d is output. When the data processing unit 27 receives the position pulse (FIG. 5 d) from the level determiner 30, it determines the phase of the received signal immediately before the position pulse is applied, and determines whether the vehicle is receiving main radiation in positive phase. It is determined that the vehicle has entered the road from the beam side (see Fig. 5e). Furthermore, the position pulse serves as a position calibration signal for a vehicle equipped with a navigation device. That is, the accumulated error is corrected by matching the position data taken in by the data processing unit 27 to the point where the position pulse was received.

The data processing unit 27 then uses a synchronization detector 26
From among the received data given from , select the correct phase corresponding data (see "A: Transmission data frame" in Figure 2) and import it (Figure 5 f), and move the road from A to
Select the intersection information, forward traffic information, and other data necessary when driving in direction B, and display the information on the display section 31.
to be displayed.

Note that in the above case, the level determiner 30
Based on the position pulse outputted from the position pulse (Fig. 5 d), the phase (positive phase) of the received signal just before it is taken in, and it is recognized that the vehicle has entered from the positive phase side, that is, the A side of the road. Instead, it may be determined that the direction in which the vehicle is traveling on the road, that is, that the vehicle is traveling from A to B, is based on the fact that the received signal changes from the positive phase to the negative phase.

When the vehicle travels from road B to road A, the operation of the receiving device is opposite to that described above, and first, the second modulated wave signal with the opposite phase is received.

With the method described above, even if the vehicle does not have a direction sensor such as a geomagnetic sensor, it is possible to select received data corresponding to the traveling direction from among various received data.

By including azimuth data indicating the direction of the road at that point in the received data corresponding to the direction of travel, vehicles traveling in each direction can know the absolute azimuth of the corresponding point.

By including intersection information, traffic information, etc. in the area ahead from that point in the received data corresponding to the direction of travel, vehicles traveling in each direction can know information on the corresponding area ahead. .

By equipping the roadside beacon system with a two-way communication function, it is possible to transmit ID signals, reception permission signals, etc. from the vehicle, and it is also possible to specify the direction of travel of the vehicle from the central station and perform vehicle calls, etc. becomes possible.

Furthermore, for vehicles equipped with a navigation device, the position pulse when the reception level suddenly drops can be used as a reference for position calibration.

<Effects of the Invention> According to the present invention, in a road-to-vehicle communication method using a roadside beacon, when the roadside beacon is a one-sided beacon, data received from one-sided beacon installed on the opposite lane is not captured. , it is possible to correctly capture only data from one side beacon installed on the driving lane side.

In addition, when the roadside beacon is a shared beacon, depending on the direction of travel of the vehicle, among the data emitted from the shared beacon, for example, while driving on an up lane, the first modulation signal and the amplitude modulation signal may be incorrect. The data received in the phase region is captured, and while driving on the down lane, the data received in the region where the first modulation signal and the amplitude modulation signal are in opposite phase is captured, so data corresponding to the direction of travel is captured correctly. A road-to-vehicle communication method can be provided.

In addition, when the roadside beacon is a one-sided beacon, communication is not performed with the roadside beacon on the opposite lane, and the vehicle can only communicate with the one-sided beacon installed on the driving lane. It can be a road-to-vehicle communication method.

[Brief explanation of the drawing]

FIG. 1A is a configuration block diagram of a roadside device according to an embodiment of the present invention, FIG. 1B is a configuration block diagram of a transmitting and receiving device mounted on a vehicle according to an embodiment of the present invention, and FIG. 1A is a diagram for explaining the signals of each part of the roadside device; FIG. 3 is a schematic perspective view showing a configuration example of a split beam antenna included in the roadside device shown in FIG. 1A;
Figure 5 and Figure 4B are diagrams showing the electric field strength distribution of radiated radio waves in a split beam antenna.
This figure is a diagram for explaining the operation of the receiving device shown in FIG. 1B, and FIG. 6 is a diagram showing a shared beacon and a one-sided beacon. 11...Data transmitter, 12...Data modulator, 1
3...Modulation signal generator, 14...Carrier wave generator, 1
5, 16...Amplitude modulator, 17...180° phase shifter, 19
...Spirit beam antenna, 20...Receiver, 2
4...Data demodulator, 25...Modulated signal demodulator, 26
...Synchronization detector, 27...Data processing unit, 28...Modulation signal regenerator, 29...Phase comparator, 30...Level determiner, 32...Transmitter.

Claims (1)

[Scope of Claims] 1. A communication method between a roadside beacon placed at a predetermined position on a road network and a vehicle traveling on the road, which comprises: , A one-sided beacon that emits various data corresponding to the direction of travel of one lane on one side of the road, or A beacon that emits various data corresponding to the direction of travel of both lanes of the road on both lanes of the road. A roadside beacon of any type of shared beacon shall be arranged, each roadside beacon shall be provided with at least two antenna elements with different main radiation directions, and a beacon type indicating whether the roadside beacon is a one-sided beacon or a shared beacon. data and the above-mentioned various data are placed on a signal using a first modulation method, the signal is divided into two, and a second modulated signal carrying position data is created by applying amplitude modulation of opposite phases to each other on the divided signals, The second modulated signal is fed to the two antenna elements of the roadside beacon so that the first modulated components are in phase, and the vehicle side receives the second modulated signal radiated from the roadside beacon and performs the second modulation. extracting the amplitude modulation signal component from the signal, demodulating the signal of the first modulation method to recognize the type of roadside beacon, and comparing the phase of the demodulated signal of the first modulation method and the extracted amplitude modulation component. . A road-to-vehicle communication method, characterized in that it is determined based on the phase comparison result and the type of roadside beacon whether or not to import data carried on the demodulated first modulation method signal. 2. The road-to-vehicle communication method according to claim 1, wherein when it is determined that the signal should be taken in, predetermined data is further transmitted to the roadside beacon after the signal is taken in. Communication method.