JPH04140934A - Mobile station equipment for radio communication between car and roadside equipments - Google Patents

Abstract

PURPOSE:To avoid occurrence of interference and disturbance due to a reflected wave from a vehicle or the like of an adjacent lane by employing 1st and 2nd on-vehicle antennas in which the direction of the major axis of the directivity pattern differs and controlling the operation of the antennas so as to select a radio wave. CONSTITUTION:A major axis 7a of a directivity pattern T of a 1st on-vehicle antenna 5 in two sets of on-vehicle antennas 5', 6' is tilted by an angle theta2 toward the left side face of a vehicle or the like from the vertical upper side of the vehicle or the like. Moreover, a major axis 8a of a directivity pattern 8 of the 2nd on-vehicle antenna 6 is tilted by an angle theta2 toward the right side face of a vehicle or the like from the vertical upper side of the vehicle or the like and the antennas are respectively fixed to a roof of the vehicle or the like. Then the operation of the antennas is selected via an antenna operation control section 21 to avoid interference and disturbance due to a reflected wave thereby improving the communication quality.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to road-to-vehicle wireless communication that is mounted on a vehicle or the like and enables wireless communication between a roadside station installed on the roadside and the vehicle or the like. The present invention relates to a mobile station device for use in mobile stations.

[Prior Art] In recent years, detailed and extensive studies have been ongoing, from needs surveys to technology confirmation, toward the practical implementation of road-to-vehicle information systems.

Road-to-vehicle information systems intermittently form spot communication areas (wireless communication areas) of about 20 to 50 meters on the road by roadside stations placed at intervals of several hundred meters to several kilometers, and vehicles traveling on these routes. This device enables wireless communication (communication of traffic information, individual communication information, etc.) between a traveling vehicle, etc. and the roadside station via a mobile station device for wireless communication mounted on a vehicle, etc. (Reference: Roadside Station). Vehicle-to-vehicle information system study group “Beacon Subcommittee Interim Report (III) J
.

Published by Japan Road New Industrial Development Organization, pp. 12-14.
, July 1988).

In a road-to-vehicle information system, a roadside station consists of a communication device and a roadside antenna for transmitting and receiving data, and a mobile station device mounted on a vehicle, etc. consists of an in-vehicle communication device for transmitting and receiving data, and a vehicle roof, etc. It consists of an on-vehicle antenna installed in the

In addition, in the road-to-vehicle information system, it is possible to pass about 4 to 6 lanes through the communication area of the roadside station, so if the up and down routes are adjacent, it is not economical to install a roadside station. Therefore, in principle, one on-street station installed on the roadside of either the up or down route covers the communication area on each lane. Therefore, the direction of the roadside station as seen from the vehicle etc. is opposite to the left or right depending on which route the vehicle is traveling on.

Therefore, for roadside stations, it is necessary to devise ways to install roadside antennas so that the communication area spreads in the width direction of the route, and for mobile station equipment, communication is good regardless of whether the route is up or down. In order to obtain the desired results, it is necessary to take measures such as installing the on-vehicle antenna.

FIG. 2(a) shows the relationship between the roadside antenna of a roadside station and the vehicle-mounted antenna of a mobile station device in a conventional road-to-vehicle information system.

A roadside antenna 1 of a roadside station is a ball 2 installed on the roadside.
It is attached to the tip of the The direction of the main axis 3a of the directivity pattern 3 of the antenna 1 is set diagonally downward by an angle θ1 from the vertical line in the direction of the route width so that the communication area spreads over a plurality of lanes. (θ
, is about 45 to 60 degrees).

On the other hand, the on-vehicle antenna 4 of the mobile station device mounted on the vehicle 4
1 is composed of one single beam antenna, and is mounted on the roof of the vehicle 4.

The direction of the main axis 42a of the directional pattern 42 of this vehicle-mounted antenna 41 is directed vertically upward so that good communication can be achieved even when traveling on either the upper or lower route.

Note that in FIG. 2(a), reference numeral 43 indicates a direct wave path that reaches the vehicle-mounted antenna 41 from the roadside antenna 1.

[Problem to be solved by the invention] As shown in Fig. 2(a), the road-to-vehicle information system has the following features:
This communication is based on the direct wave path 43 under almost line-of-sight conditions, and in principle, it is expected that there will be the possibility of high-quality, high-speed (for example, 512 kb/s) digital communication with less interference caused by reflected waves. .

However, in the conventional system shown in FIG. 2(a), when considering the realistic environment of road traffic, as shown in FIG. 2(b), An unnecessary wireless line is formed by the reflected wave path 45, and this wireless line by the reflected wave path 45 causes interference with the original wireless line by the direct wave path 43,
There was a risk that communication quality would deteriorate.

Such a reflected wave path 45 occurs not only when the vehicle is running parallel to the vehicle in the adjacent lane as shown in FIG. They may be formed even when driving in a lane, and therefore, when there are many lanes and traffic flow is complicated, interference will occur more frequently and there is a risk that communication quality will further deteriorate. be.

Therefore, as a measure on the roadside station side to prevent the above-mentioned interference, the ball 2 that supports the roadside antenna 1 is made higher so that the reflected waves from the adjacent vehicle reach the vehicle in question using geometric optics. It was proposed to reduce the probability.

However, the measure of increasing the height of the ball 2 is undesirable because it poses new problems regarding the structural constraints of the road and the appearance of the road.

The present invention has been made in view of the above-mentioned circumstances, and is capable of being carried out without being subject to structural constraints of the road, without damaging the scenery of the road, and which prevents reflections from vehicles in adjacent lanes. An object of the present invention is to provide a mobile station device for road-to-vehicle wireless communication that can avoid interference caused by waves.

[Means for Solving the Problem] The mobile station device for road-to-vehicle wireless communication according to claim 1 is mounted on a vehicle, etc., and is capable of wireless communication between a roadside station installed on the roadside and the vehicle, etc. It makes it seem possible.

Specifically, it includes two vehicle-mounted antennas, a first and a second vehicle-mounted antenna, for transmitting and receiving information to and from the roadside antenna of the roadside station, and an antenna operation control unit that controls the operation of these two vehicle-mounted antennas. It is equipped with the following.

Of the two vehicle-mounted antennas, the first vehicle-mounted antenna has a directivity pattern whose main axis is inclined from vertically above the vehicle to the left side of the vehicle, and the second vehicle-mounted antenna The main axis of the gender pattern is inclined from vertically above the vehicle to the right side of the vehicle.

Further, the antenna operation control section is configured to be able to switch between a first selection mode in which only the first vehicle-mounted antenna is in operation and a second selection mode in which only the second vehicle-mounted antenna is in operation.

In the communication area using the roadside antenna, communication is performed by setting a mode in which only the vehicle-mounted antenna whose main axis of turn is directed toward the roadside antenna side is set by the antenna operation control unit.

Further, in the mobile station device for road-to-vehicle wireless communication according to claim 2, the antenna operation control section according to claim 1 comprises the first
In addition to the second selection mode, a combined operation mode in which both the first and second vehicle-mounted antennas are in operation can be selected.

The present invention is characterized in that the vehicle-mounted antenna is set with the main axis of the N-turn directivity directed toward the roadside antenna, based on the amount of transient change in the received electric field level accompanying switching of each mode in the antenna operation control section.

Further, in the mobile station device for road-to-vehicle wireless communication according to claim 3, the antenna operation control unit operates a mode in which only the vehicle-mounted antenna whose directivity pattern has its main axis directed toward the roadside antenna side is operated in the communication area that has passed first. When set, the set mode is temporarily stored.

The present invention is characterized in that when setting a mode in the next communication area, priority is given to switching to the stored mode.

"Operation" Reflected waves from other vehicles, etc. that degrade communication quality due to interference enter the vehicle-mounted antenna from a direction different from that of the direct waves from the roadside antenna.

However, in the mobile station device for road-to-vehicle wireless communication according to claim 1, in the communication area using the roadside antenna, only the vehicle-mounted antenna in which the main axis of the directivity pattern is inclined toward the roadside antenna operates effectively. While off-beam loss is reduced for direct waves from the antenna, off-beam loss increases for reflected waves incident from a direction different from the direct wave from the roadside antenna, so in reality, the reflected waves It is possible to avoid the occurrence of interference caused by.

In addition, there is no need for any special improvements on the roadside station side, and this is achieved by improving the configuration of the mobile station device itself, so it is not subject to the structural constraints of the road and does not damage the scenery of the road. It can be carried out.

Further, as described in claim 2, the modes for setting the operating states of the first and second vehicle-mounted antennas include a combined operation mode in which both the first and second vehicle-mounted antennas are in the operating state; In a configuration that has three modes: a first selection mode in which only the second in-vehicle antenna is in operation, and a second selection mode in which only the second in-vehicle antenna is in operation, for example, the combination operation mode is set in advance. When approaching the communication IJA set by the roadside antenna and entering the communication area, the mode is sequentially switched to the first selection mode and the second selection mode, and changes in the received electric field level accompanying the mode switching are monitored. By doing so, the direction of the roadside antenna can be easily and reliably recognized.

Moreover, as described in claim 3, the mode used for communication in the previous communication area is temporarily stored, and when selecting the mode in the next communication area, priority is given to switching to the stored mode. If so, the mode selection process can be shortened, for example, when driving long distances in the same direction on one route (i.e., when the installation direction of the roadside antenna does not change with respect to the direction of travel of the vehicle, etc.). , the effective period of communication within the communication area can be increased accordingly.

Embodiment FIG. 1 shows the configuration of an embodiment of a mobile station device for road-to-vehicle wireless communication according to the present invention.

The mobile station device of this embodiment is mounted on a vehicle, etc., and enables wireless communication between a roadside station installed on the roadside and the vehicle, etc., and is capable of communicating with a roadside antenna of the roadside station. two vehicle-mounted antennas 5.6, a first and second vehicle-mounted antenna for transmitting and receiving information, an antenna operation control section 21 that controls the operation of these two vehicle-mounted antennas 5 and 6, and an antenna operation control section 21 that controls the operation of these two vehicle-mounted antennas 5 and 6; Transmission/reception common unit 2 connected to unit 2I
4, a receiver section 22 that receives and receives received information via the transmitting/receiving common section 24 and performing predetermined processing, and a transmitting section 23 that outputs information to be transmitted to the antenna side via the transmitting/receiving common section 24. and a mode setting circuit 25 for setting the operation mode in the antenna operation control section 21.

Here, the two vehicle-mounted antennas 5.6 are both monoplane beam antennas, but the first vehicle-mounted antenna 5 directs the main axis 7a of the directivity pattern 7 from vertically above the vehicle, etc. to the left side of the vehicle, etc. The main axis 8a of the directivity pattern 8 of the second in-vehicle antenna 6 is tilted at an angle θ from vertically above the vehicle to the right side of the vehicle, respectively. , is fixed to the roof of a vehicle, etc. (θ is approximately 30 to 60 degrees).

FIG. 3(a) shows the vehicle-mounted antennas 5 and 6 in relation to the roadside antenna 1 of the roadside station.

A roadside antenna 1 is attached to the tip of a ball 2 provided on the roadside. The direction of the main axis 3a of the directivity pattern 3 of the antenna 1 is set diagonally downward by an angle θ1 from the vertical line in the direction of the route width so that the communication area spreads over a plurality of lanes. (θ, is 45
(approximately 60 degrees).

Note that in this illustrated example, the first vehicle-mounted antenna 5 is located on the roadside antenna 1 side.

The antenna operation control section 21 is configured to operate the antenna 5.6 described above.
Switches 211, 212 for opening and closing signal paths 30.31 connected to these switches 211. ．． An opening/closing control circuit 213 that controls the operation of the antenna 5,
As shown in FIG. Three operating modes A, B.

C can be selectively set (the combiner 214 is connected to the duplexer 24).

Mode A is a first selection mode in which only the first in-vehicle antenna 5 is in operation, transmitting and receiving is performed by the antenna 5, the switch 211 is turned ON (closed), and the switch 212 is set to 0F.
This can be obtained by setting it to F (open).

Mode B is a second selection mode in which only the second in-vehicle antenna 6 is in an operating state, and the antenna 6 transmits and receives data, and the switch 211 is set to 0FF (open) and the switch 212 is set to OFF.
This can be obtained by setting it to N (closed).

Mode C is a combined operation mode in which only the second vehicle-mounted antenna 6 is in an operating state, both the first and second vehicle-mounted antennas 5.6 are in an operating state, and reception is performed using both antennas 5 and 6. Both the switches 211 and 212 are set to O.
This can be obtained by setting it to N (closed).

When receiving a received signal from an antenna, the receiver section 22 sets the received electric field level to the mode setting circuit 25.
It has a function to notify you.

Further, the receiver section 22 and the transmitter section 23 are equipped with connection terminals 27.2!8 for connecting in-vehicle information terminal equipment. Note that the in-vehicle information terminal device referred to herein refers to a terminal device for receiving and transmitting signals such as ID information, navigation information 1 individual communication information, and the like.

The mode setting circuit 25 outputs a predetermined control signal to the opening/closing control circuit 213 based on the received electric field level signal received from the receiver section 22 and the control signal input from the external control terminal 26, and controls the antenna operation. The operation mode in the control unit 21 is set.

The operation of the mode setting circuit 25 is based on the external control terminal 2.
It is possible to switch between automatic and manual operation according to a control signal input from 6.

When the operation of the mode setting circuit 25 is set to manual,
The mode setting circuit 25 sets the operation mode in the antenna operation control section 21 based on a control signal inputted to the external control terminal 26 by manual operation by an operator (such as a driver of a vehicle, etc.).

Further, when the operation of the mode setting circuit 25 is set to automatic, the mode setting circuit 25 performs a predetermined mode setting process according to a program prepared in advance to set the operation mode in the antenna operation control section 21.

The mode setting process when the operation of the mode setting circuit 25 is set to automatic is as shown in FIG.
It can be explained by dividing into four periods: O, operation mode selection period T1, communication effective period (road-to-vehicle information communication period) T2, and operation mode return period T3.

Each of these periods is a period that sequentially elapses each time a mobile station device in motion passes through a communication area by a roadside station.

The out-of-communications area period TO is a period during which the vehicle is traveling in a section that is not included in the communication area between roadside stations, and during this period TO, the operation mode in the antenna operation control section 21 is set to mode C.

The operation mode selection period T1 is a point in time when the mobile station device gradually approaches the communication area (minimum wireless zone) from the section between roadside stations and the received electric field level extracted from the receiver section 22 reaches a predetermined value. This is a period transitioning from the period TO.

In this operation mode selection period T1, it is determined which of the first and second vehicle-mounted antennas 5 and 6 is directed toward the roadside antenna 1, and a directional pattern is formed on the roadside antenna 1 side. The operation mode in the antenna operation control section 21 is set to mode A or mode B so that only the vehicle-mounted antenna with its main axis directed is in operation.

During this period TI, determining which of the first and second vehicle-mounted antennas 5 and 6 is directed toward the roadside antenna 1 is determined by changing the operation mode in the antenna operation control unit 21 from mode C to mode A. This is performed by sequentially switching the mode to mode B and B, and monitoring the amount of transient change in the received electric field level accompanying this mode switching.

In other words, when a vehicle-mounted antenna with the main axis of the directivity pattern directed toward the roadside antenna 1 is selected by mode switching, the amount of change is relatively small (for example, 5 dB or less); If an on-vehicle antenna with the main axis of the directivity pattern directed in the opposite direction is selected, a considerable amount of change (for example, 10 dB or more) will occur.

Also, if we focus on the transient change in the received electric field level due to switching from mode A to mode B1 or from mode B to mode A, we can see that the main axis of the directional pattern is directed toward the side where the roadside antenna 1 is installed. When the antenna is selected, it exhibits a much higher received field level.

Therefore, first, from mode C to mode A, or from mode C
If the mode is switched from mode B to mode B, and the amount of transient change in the received electric field level due to the mode switch is less than a predetermined value, the operation mode obtained by the switch will be applied to the main axis of the directivity pattern on the roadside antenna side. It is determined that the on-vehicle antenna that is aimed at is the selected mode. In addition, if the amount of transient change in the received electric field level due to the mode switching is greater than or equal to a predetermined value, the operating mode obtained by the switching will be Since this is the mode in which the antenna was selected,
The mode will be switched to the remaining selection mode, but
In this way, when switching the mode from mode A to mode B or from mode B to mode A,
Confirm that the received electric field level increases significantly as the mode is switched.

In this operation mode selection period T1, when the mode setting is completed, the communication effective period (road-to-vehicle information communication period) immediately shifts to T2. During this communication validity period T2,
The operation mode in the antenna operation control section 21 is maintained at the mode selected in the above-mentioned period T1, and substantial communication is performed.

When the mobile station device escapes from the communication area formed by the roadside antenna 1, this is detected when the received electric field level falls below a predetermined value, and the antenna operation control unit 21 operates to return the operation mode to mode C. After the mode return period T3, the process returns to the out-of-communications area period TO.

The mode setting process described above is carried out by operating the opening/closing control circuit 213 using a control signal generated by the mode setting circuit 25.

In addition, in the above process, “
The reason why we focused on "the amount of transient change in the received electric field level" is as follows.

That is, during the operation mode selection period T1, the running vehicle is approaching the roadside station, the propagation distance of the direct wave path between the road and the vehicle is gradually shortening, and the received electric field level is also gradually increasing. It is convenient to focus on the amount of transient change that accompanies switching within (for example, about 10 m5 or less). However, if the receiver section 22 is equipped with an AGC function (automatic gain control function), the mode setting circuit 25 monitors the reception level at the previous stage of the AGC feedback loop.

Further, the mode setting circuit 25 of this embodiment is equipped with a memory that stores the operating mode used for communication at the roadside station that was passed immediately before (that is, the operating mode during the communication effective period T2). When switching the operation mode of the antenna operation control unit 21 to operation mode C in the operation mode return period T3, the operation mode symbol before switching is written in the memory. Then, during mode setting processing in the next communication area, the operation mode is selected with priority given to switching to the operation mode stored in the memory.

The roadside where the roadside antenna l is installed is often the same depending on the route (for example, the roadside on the upbound lane), and as long as the vehicle is traveling in the same direction on the same route and does not change course at intersections, etc., it should be selected. The operating mode is constant, and in such a state, the operating mode selected in the communication area just passed through and written in the memory is very useful, and is effective in simplifying the selection process and shortening the selection period. do.

As shown in FIG. 3(b), reflected waves 11 from other vehicles 10 that degrade communication quality due to interference enter the vehicle antenna from a direction different from that of the direct waves 9 from the roadside antenna 1.

However, in the mobile station device of the embodiment described above, in the communication area by the roadside antenna 1, only the vehicle-mounted antenna 5 in which the main axis of the finger identity pattern is inclined toward the roadside antenna 1 operates effectively. While the off-beam loss is reduced for the direct wave 9 from the antenna 1,
Since the off-beam loss is large for reflected waves 11 that are incident from a direction different from the direct wave 9 from roadside antenna 1, it is possible to substantially avoid interference caused by reflected waves.

Note that if we focus on a vehicle traveling in a lane far from the roadside where the roadside station is installed, the direct wave from the roadside antenna 1 will be far away from the vertical direction above the vehicle, especially in the case of a large vehicle with a high vehicle height. The light will be incident from an inclined direction. Therefore, the configuration in which the main axis of the directional pattern of the on-vehicle antenna 5.6 is inclined from the vertical line toward the roadside causes a large off-beam loss to the reflected wave 11 via the vehicle body traveling in the adjacent lane, and at the same time This is an important point in terms of reducing off-beam loss to direct waves 9.

In addition, the above-mentioned embodiment does not require any special improvement on the roadside station side, but is handled by improving the configuration of the mobile station device itself. It can be implemented without damaging the scenery of the road.

Furthermore, as modes for setting the operating states of the first and second vehicle-mounted antennas, there is a mode C in which both the first and second vehicle-mounted antennas are set to the operating state, and a mode C in which the first and second vehicle-mounted antennas are both set to the operating state.
It has three modes: mode A in which only the second in-vehicle antenna 6 is in operation, and mode B in which only the second vehicle-mounted antenna 6 is in operation. The direction of the roadside antenna can be easily and reliably recognized by switching the operating mode from mode C to mode A or mode B at the time of approach and comparing the received electric field level accompanying the mode switching.

In addition, the mode used for communication in the previous communication area is temporarily stored, and priority is given to switching to the memorized mode when selecting the mode in the next communication area. When traveling long distances in the same direction (i.e., when the installation direction of the roadside antenna does not change with respect to the traveling direction of the vehicle, etc.), the mode selection process can be shortened, and communication within the communication area can be improved accordingly. Validity period T
2 can be increased.

In the case of one embodiment, the number of operation modes that can be set in the antenna operation control unit 21 is three, but the composite operation mode C is omitted and only the first selection mode A and the second selection mode B are set. It may also be configured to obtain This is because, as described above, the vehicle-mounted antenna facing the roadside antenna 1 can be selected by comparing the received electric field level in mode A and the received electric field level in mode B.

However, if only these two modes A and B are used,
During the out-of-communication area period TO, if an operation mode is not selected in which the vehicle-mounted antenna facing the roadside antenna 1 is put into operation, it may become difficult to detect movement in the communication area based on the received electric field level.

Further, in the case of the above embodiment, the operation mode in the antenna operation control section 21 can be set either automatically or manually, but it is also possible to set it only automatically or only manually.

Commercial vehicles such as long-distance trucks often travel on the same route in the same direction, and in such driving conditions, the installation direction of the roadside antenna remains the same for a long period of time.
It is more advantageous to set the mode manually.

In other words, roadside a.c.
Once you manually set the mode in which only the in-vehicle antenna facing the antenna side operates, there is almost no need to switch the operation mode from now on, and the entire period of driving within the communication area is the effective communication period. This is because it can be effectively used as T2.

However, in urban areas where the route of travel changes within a short period of time, or where traffic flow is complicated,
It is more advantageous to perform mode switching automatically.

In other words, the driver of a vehicle, etc. no longer needs to pay attention to road signs indicating the location of a station on the road every time he or she changes the driving route, which reduces the mental burden that the driver faces when driving. At the same time, it prevents erroneous setting of the operation mode due to overlooking the roadside station location sign7, etc.1. This is because high-quality communication with little interference can always be ensured.

1. Effects of the Invention In the mobile station for road-to-vehicle wireless communication according to claim 1, in the communication area by the roadside antenna, the main axis of the finger, same-sex butter, and the like is tilted toward the roadside antenna. Since this is a configuration in which only the vehicle-mounted antenna operates effectively, off-beam loss is reduced for direct waves from the roadside antenna, but it reduces off-beam loss for reflected waves incident from a direction different from the direct wave from the roadside antenna. The effect of increasing the off-beam loss is obtained, and as a result, it is possible to substantially avoid interference caused by reflected waves.

(For case 7, there is no need for any special improvement on the roadside station, and this can be addressed by improving the configuration of the mobile station device itself.
It can be implemented without being subject to structural constraints of the road and without damaging the appearance of the road.

Further, as described in claim 2, a motor for setting the operating state of the No. 1 and the 20th in-vehicle antenna,
and a composite operating element ・-1・′ which puts both of the 20th width mounted antenna into the operating state, a first selection mode which puts only the first vehicle-mounted antenna into the operating state, and only the second vehicle-mounted antenna ・-1・′ which operates only the second vehicle-mounted antenna. In a configuration having three modes including a second selection mode that is a
7. When approaching the communication area set by the roadside antenna and entering the communication area, switch the mode to the first selection mode and the second selection mode in order, and
By monitoring changes in the received electric field level due to mode switching, the direction of the roadside antenna can be easily and reliably recognized.

Moreover, as described in claim 3, the mode used for communication in the previous communication area is stored in memory, and switching to the stored mode is performed when selecting the mode in the next communication area. If the configuration gives priority to By shortening the processing time,
It is also possible to increase the communication validity period within the communication area.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of an embodiment of the present invention, Figures 2 (a) and (b') are explanatory diagrams of a conventional road-to-vehicle information system, and Figures 3 (a) and (b) are FIG. 4 is an explanatory diagram of the operation mode in one embodiment, and FIG. 5 is an explanatory diagram of mode setting in one embodiment. 1... Roadside antenna, 5, 6... Vehicle-mounted T antenna, 7.8... Directivity pattern, 7a,
8a...Main shaft, 21...Antenna operation control section, 22...Receiver section, 23...
Transmission section a, 24... Transmission/reception common section, 25...
...Mode setting circuit, 26...External control terminal,
211.212... Switch, 213...
・Opening/closing control circuit, 4...6 components.

Claims (3)

[Claims] (1) A mobile station device for road-to-vehicle wireless communication that is mounted on a vehicle or the like and enables wireless communication between a roadside station installed on the roadside and the vehicle, the device being connected to a roadside antenna of the roadside station. first and second for transmitting and receiving information between
and an antenna operation control unit that controls the operation of these two vehicle-mounted antennas, and of the two vehicle-mounted antennas, the first vehicle-mounted antenna has a main axis of a directional pattern. The second in-vehicle antenna is installed with the main axis of the directional pattern tilted from vertically above the vehicle, etc. toward the right side of the vehicle, etc. The antenna operation control unit is configured to be able to switch between a first selection mode in which only the first vehicle-mounted antenna is in operation and a second selection mode in which only the second vehicle-mounted antenna is in operation; A mobile station for road-to-vehicle wireless communication, characterized in that in a communication area using an antenna, the antenna operation control section sets a mode in which only a vehicle-mounted antenna with a main axis of a directional pattern directed toward the roadside antenna operates, and performs communication. Device. (2) The antenna operation control section is configured to control the first and second antenna operation control sections.
In addition to the selection mode, a combined operation mode in which both the first and second vehicle-mounted antennas are in operation is configured to be selectable, and the transient state of the received electric field level accompanying switching of each mode in the antenna operation control section is configured to be selectable. 2. The mobile station device for road-to-vehicle wireless communication according to claim 1, wherein the vehicle-mounted antenna is set so that the main axis of the directivity pattern is directed toward the roadside antenna based on the amount of change. (3) When the antenna operation control unit sets a mode in which only the vehicle-mounted antenna with the main axis of the directional pattern directed toward the roadside antenna side operates in the communication area that was passed through first,
Claim 1 or 2, wherein the set mode is temporarily stored, and when setting the mode in the next communication area, priority is given to switching to the stored mode. A mobile station device for road-to-vehicle wireless communication according to.