JPH0314368B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a road communication device used for road-to-vehicle communication.

<Prior art and its problems> Conventionally, in road-to-vehicle communication that communicates between an on-board communication device mounted on a vehicle and a roadside communication device, one antenna and one roadside communication device are used for each communication area. There is a system that performs communication by installing roadside communication devices each consisting of a main body, but this method has the disadvantage of high cost because it is necessary to install multiple roadside communication devices in each communication area. be.
For this reason, a roadside communication device is configured with multiple antennas and one roadside communication device main body, and the roadside communication device itself is installed at an appropriate position, and multiple communication areas are connected to the roadside communication device main body. The transmission control unit for controlling communication within the main body, the modulation/demodulation unit for modulating and demodulating the transmitted and received signals, and the amplifier for amplifying the transmitted and received signals shall be used in common for each antenna. Some methods have been used to reduce costs. However, in this method, as shown in the communication time chart in FIG. Later, a polling signal P2 is transmitted from the antenna A2, a polling signal Pn is transmitted from the antenna An in the same manner, and a polling signal is transmitted again from the antenna A1, thereby performing time-division polling. Therefore, the interval between polling signal transmissions for each communication area is as long as t×n,
Therefore, especially in the case of a high-speed vehicle, there is a problem that the vehicle may pass through the communication area during the transmission interval and communication may not be possible. Note that FIGS. 4A to 4C show time charts of communication between antennas A1 to An, respectively, FIG. 4D shows a time chart of communication of the on-vehicle communication device, and FIG.
D1' indicates an information signal transmitted from the in-vehicle communication device.

<Purpose of the invention> An object of the present invention is to solve the above-mentioned technical problems and provide a roadside communication device that has an economical configuration and can prevent communication failures due to delays in polling signal transmission. do.

<Configuration and Effects of the Invention> In order to achieve the above-mentioned object, the present invention comprises antennas installed in each of a plurality of communication areas, and one roadside communication device body to which each of the antennas is connected. , the main body of the road communication device is
a transmission control unit for controlling communication with the in-vehicle communication device; a modulation unit for modulating a signal to be transmitted to the in-vehicle communication device; a demodulation unit for demodulating a received signal from the in-vehicle communication device; Selection for selecting an amplifier that amplifies input/output and an antenna output that receives a signal from the in-vehicle communication device that responds fastest to the polling signal when polling signals are simultaneously transmitted from each antenna to the in-vehicle communication device. and a gate circuit that provides a signal from the vehicle-mounted communication device that responded fastest to the demodulation section based on the output of the selection circuit.

Therefore, according to the present invention, polling signals are simultaneously transmitted from a plurality of antennas and communication is performed with the in-vehicle communication device that responded the fastest to the polling signal, thereby preventing communication failure due to a delay in polling signal transmission. Furthermore, by sharing the modulation/demodulation section, the amplifier, and the transmission control section, it is possible to reduce costs.

<Description of Examples> Examples of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of one embodiment of the present invention. The road communication device 1 of the present invention basically includes a plurality of (four in this embodiment) antennas A1.
~A4, and a road communication device main body 2 to which the antennas A1 to A4 are respectively connected. In this embodiment, these antennas A1 to A4 are installed in each communication area of the intersection, as shown in FIG.

The roadside communication device main body 2 includes a transmission control section 3 for controlling communication with an on-board communication device of a vehicle traveling at the intersection, and a modulation section 4 for modulating a transmission signal to the on-board communication device. , a demodulator 5 that demodulates the received signal from the in-vehicle communication device, and antennas A1 to A.
Amplifiers 6 to 9 individually corresponding to antennas A1 to A4, and selection for selecting the antenna output that received the signal from the in-vehicle communication device that responded fastest to the polling signal transmitted simultaneously from each antenna A1 to A4 as described later. It includes a circuit 10 and a gate circuit 11 that provides a signal from the vehicle-mounted communication device that responded fastest based on the output from the selection circuit 10 to the demodulator 5. Each amplifier 6-9 corresponds individually to antenna A1-A4.
are transmission amplifiers 6a to 9a for amplifying the transmission signal from the modulation section 4, and reception amplifiers 6b to 9b for amplifying the reception signals from the antennas A1 to A4.
It consists of

FIG. 3 is a time chart of communication in the embodiment shown in FIG. 1, and FIGS. 3A to 3D are antenna A1
~A4 communication time charts are shown,
FIG. 3E shows a time chart of communication by the on-vehicle communication device. In the roadside communication device 1 of the present invention, polling signals P1 to P4 are simultaneously transmitted at fixed time intervals t from antennas A1 to A4 installed in each communication area.
Send by. The selection circuit 10 selects the antenna output that received the signal from the in-vehicle communication device that responded fastest to these polling signals P1 to P4, in this embodiment, the information signal D1 from the in-vehicle communication device of the vehicle 15.
The output of the antenna A2 that received the signal is selected and the output is given to the gate circuit 11. In response to the output from the selection circuit 10, the gate circuit 11 allows only the received signal from the antenna A2 to pass through and provides it to the demodulation section 5, and the received signal demodulated by the demodulation section 5 is provided to the transmission control section 3. Thereafter, the vehicle-mounted communication device that responded first continues communication until the communication is completed.

In this way, since the polling signals from each antenna A1 to A4 are transmitted simultaneously, the fourth
Compared to the conventional example shown in the figure, there is no polling delay,
This makes it possible to prevent communication failure. Furthermore, compared to the conventional method in which roadside communication equipment is installed in each communication area, transmission control units, amplifiers,
It is economical because the modulation section and the demodulation section can be shared.

When communicating with the in-vehicle communication device that responded first, it is possible to send the same information to all antennas by specifying the communication partner, or to send information only to the specific antenna that responded. You can send it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure is a diagram for explaining the arrangement of the embodiment shown in FIG.
FIG. 3 is a time chart of communication in the embodiment shown in FIG. 1, and FIG. 4 is a time chart of communication in the conventional example. 1... Road communication device, 2... Road communication device body, 3
...Transmission control section, 4...Modulation section, 5...Demodulation section,
6-9...Amplifier, 10...Selection circuit, 11...
Gate circuit, A1-A4...antenna.

Claims (1)

[Claims] 1 A roadside communication device for communicating with an on-board communication device mounted on a vehicle, which includes antennas installed in each of multiple communication areas, and one roadside communication device to which each of the antennas is connected. The on-road communication device main body includes a transmission control section for controlling communication with the on-vehicle communication device, a modulation section that modulates a signal to be transmitted to the on-vehicle communication device,
a demodulator that demodulates a received signal from the on-vehicle communication device;
an amplifier that amplifies input and output from the antenna;
A selection circuit for selecting the antenna output that received a signal from the in-vehicle communication device that responded fastest to the polling signal when polling signals are simultaneously transmitted from each antenna to the in-vehicle communication device; and an output of the selection circuit. and a gate circuit that provides a signal from the vehicle-mounted communication device that responded fastest to the demodulation section based on the above.