Patent Publication Number: US-2022215752-A1

Title: Roadside apparatus and traffic communication system

Description:
RELATED APPLICATIONS 
     The present application is a continuation based on PCT Application No. PCT/JP2020/034890, filed on Sep. 15, 2020, which claims the benefit of Japanese Patent Application No. 2019-176220 filed on Sep. 26, 2019. The content of which is incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a roadside apparatus and a traffic communication system. 
     BACKGROUND ART 
     In recent years, as a technology that can reduce the occurrence of traffic accidents, intelligent transport systems (ITS) have been attracting attention. For such intelligent transport systems, a roadside apparatus being a base station provided near a road is used. 
     NPL 1 describes a roadside apparatus including a rod antenna. In the roadside apparatus, two antenna connection terminals are provided on an upper surface being the top surface of a housing in an installation state in which the roadside apparatus is installed. The rod antenna (rod antenna) is connected to each antenna connection terminal, and road-to-vehicle communication being communication between the roadside apparatus and a vehicle is performed via the rod antenna. 
     CITATION LIST 
     Non Patent Literature 
     NPL 1: RSU-101E_datasheet, [online], [searched on Sep. 20, 20191, the Internet &lt;URL: https://file01.itaiwantrade.com/15b880a7-9f47-484f-aa3c-a185da334d1b/RSU-101E_datasheet.pdf&gt; 
     SUMMARY OF INVENTION 
     A roadside apparatus according to the first aspect includes: a housing including an antenna mounting surface; an antenna connection terminal being provided on the antenna mounting surface, and supporting both a rod antenna and a planar antenna; and a circuit being housed in the housing, and being configured to perform road-to-vehicle communication via a connection antenna connected to the antenna connection terminal. An area of the antenna mounting surface is equal to or larger than an area of the planar antenna. An antenna selected out of the planar antenna and the rod antenna is connected, as the connection antenna, to the antenna connection terminal. 
     A traffic communication system according to the second aspect includes: the roadside apparatus according to the first aspect; and an in-vehicle device configured to perform road-to-vehicle communication with the roadside apparatus. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating a configuration of a traffic communication system according to an embodiment. 
         FIG. 2  is a block diagram illustrating a schematic configuration of a roadside apparatus according to an embodiment. 
         FIG. 3A  is a diagram illustrating a directional pattern of planar antennas according to an embodiment. 
         FIG. 3B  is a diagram illustrating a directional pattern of the planar antennas according to an embodiment. 
         FIG. 4  is a perspective view of a housing seen from an installation surface side regarding the roadside apparatus to which rod antennas are connected according to an embodiment. 
         FIG. 5  is a perspective view of the housing seen from the installation surface side regarding the roadside apparatus to which the planar antennas are connected according to an embodiment. 
         FIG. 6  is a perspective view of the housing seen from a front surface side regarding the roadside apparatus to which the rod antennas are connected according to an embodiment. 
         FIG. 7  is a perspective view of the housing seen from the front surface side regarding the roadside apparatus to which the planar antennas are connected according to an embodiment. 
         FIG. 8  is a diagram illustrating an installation example of the roadside apparatus regarding the roadside apparatus to which the rod antennas are connected according to an embodiment. 
         FIG. 9  is a diagram illustrating an installation example of the roadside apparatus regarding the roadside apparatus to which the rod antennas are connected according to an embodiment. 
         FIG. 10  is a diagram illustrating a directional pattern of the roadside apparatus when the roadside apparatus to which the rod antennas are connected is installed at an intersection according to an embodiment. 
         FIG. 11  is a diagram illustrating an installation example of the roadside apparatus regarding the roadside apparatus to which the planar antennas are connected according to an embodiment. 
         FIG. 12  is a diagram illustrating a directional pattern of the roadside apparatus when the roadside apparatus to which the planar antennas are connected is installed at an intersection according to an embodiment. 
         FIG. 13A  is a diagram illustrating outer appearance configuration example 1 of the roadside apparatus according to an embodiment. 
         FIG. 13B  is a diagram illustrating outer appearance configuration example 1 of the roadside apparatus according to an embodiment. 
         FIG. 14A  is a diagram illustrating outer appearance configuration example 2 of the roadside apparatus according to an embodiment. 
         FIG. 14B  is a diagram illustrating outer appearance configuration example 2 of the roadside apparatus according to an embodiment. 
         FIG. 15A  is a diagram illustrating outer appearance configuration example 3 of the roadside apparatus according to an embodiment. 
         FIG. 15B  is a diagram illustrating outer appearance configuration example 3 of the roadside apparatus according to an embodiment. 
         FIG. 16  is a diagram illustrating the roadside apparatus according to another embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In general, a rod antenna has characteristics in that it has no directivity or low directivity. Such a roadside apparatus is referred to as an omnidirectional roadside apparatus. It is considered that the omnidirectional roadside apparatus is installed at an intersection where two or more roads cross, for example, and is used for the purpose of performing road-to-vehicle communication with a vehicle on each of the two or more roads. 
     Meanwhile, for the purpose of performing road-to-vehicle communication with a vehicle on a specific road at an intersection, it is desirable that an antenna having high directivity, for example, a patch antenna (planar antenna), be provided in a roadside apparatus. Such a roadside apparatus is referred to as a directional roadside apparatus. 
     However, a conventional roadside apparatus has low versatility, and accordingly an omnidirectional roadside apparatus and a directional roadside apparatus need to be separately manufactured and provided depending on a road environment in which the roadside apparatus is installed and the purpose of the roadside apparatus. 
     In view of this, the present disclosure has an object to provide a roadside apparatus and a traffic communication system having high versatility that can be adapted to various road environments and purposes. 
     A traffic communication system according to an embodiment will be described with reference to the drawings. Note that, in the following description regarding the drawings, the same or similar parts are denoted by the same or similar reference signs. 
     Configuration of Traffic Communication System 
     First, a configuration of a traffic communication system according to an embodiment will be described.  FIG. 1  is a diagram illustrating a configuration of a traffic communication system  1  according to an embodiment. 
     As illustrated in  FIG. 1 , the traffic communication system  1  includes a vehicle  100  that passes through on a road R, and a roadside apparatus  200  being a base station installed on a roadside of the road R. “The vehicle  100  passes through” includes a state in which the vehicle  100  travels (moves) and a state in which the vehicle  100  temporarily stops. 
     In  FIG. 1 , vehicles  100 A and  100 B are illustrated as the vehicle  100 , and roadside apparatuses  200 A and  200 B are illustrated as the roadside apparatus  200 . Note that although an automobile such as a standard-sized automobile and a light automobile is illustrated as the vehicle  100 , a vehicle that travels on the road R may suffice, and for example, a two-wheel motor vehicle (motorcycle) or the like may suffice as well. 
     Each vehicle  100  is equipped with an in-vehicle device  150  being a mobile station that performs wireless communication. The in-vehicle device  150  performs road-to-vehicle communication with the roadside apparatus  200 .  FIG. 1  illustrates an example in which an in-vehicle device  150 A and the roadside apparatus  200 A perform road-to-vehicle communication, and an in-vehicle device  150 B and the roadside apparatus  200 B perform road-to-vehicle communication. 
     The roadside apparatus  200  is installed near the road R. The roadside apparatus  200  may be installed at an intersection where two or more roads cross. 
     The roadside apparatus  200  may perform road-to-road communication with another roadside apparatus  200 .  FIG. 1  illustrates an example in which the roadside apparatus  200 A and the roadside apparatus  200 B perform road-to-road communication by means of wireless communication; however, the road-to-road communication may be wired communication. 
     In the example illustrated in  FIG. 1 , the roadside apparatus  200 A is installed at a traffic light (traffic signal)  300  or a support for the traffic light  300 , and operates in corporation with the traffic light  300 . For example, the roadside apparatus  200 A transmits a radio signal including signal information related to the traffic light  300  to the vehicle  100  (in-vehicle device  150 ). For such road-to-vehicle communication, broadcast wireless communication in which communication is performed for a large number of unspecified endpoints may be used. Alternatively, for the road-to-vehicle communication, multicast wireless communication in which communication is performed for a large number of specified endpoints may be used, or unicast wireless communication in which communication is performed for a single specified endpoint may be used. 
     Each roadside apparatus  200  is connected to a server  400  via a communication channel. The communication channel may be a wired channel, or may be a wireless channel. A vehicle detector installed at the roadside may be connected to the server  400  via the communication channel. From each roadside apparatus  200 , the server  400  receives information that the roadside apparatus  200  receives from the in-vehicle device  150 , such as a position and a vehicle speed of the vehicle  100 . The server  400  may further receive vehicle detection information from a roadside sensor installed on the road R. The server  400  collects and processes various pieces of traffic information, based on the received information, and thereby manages road traffic. 
     Schematic Configuration of Roadside Apparatus 
     Next, schematic configurations of the roadside apparatus  200  according to an embodiment will be described.  FIG. 2  is a block diagram illustrating a schematic configuration of the roadside apparatus  200  according to an embodiment. 
     As illustrated in  FIG. 2 , the roadside apparatus  200  includes a housing  210 , a plurality of antenna connection terminals  220  ( 220   a  to  220   d ), a plurality of connection antennas  230  ( 230   a  to  230   d ), a plurality of external connection terminals  240  ( 240   a  and  240   b ), and a circuit  250 . The embodiment will mainly describe an example in which the number of antenna connection terminals  220  is four. However, the number of antenna connection terminals  220  may be three or less, or may be five or more. 
     The housing  210  is a box-like exterior structure that houses the circuit  250  and includes a frame. The housing  210  includes antenna mounting surfaces  211  and an installation surface  212  (not illustrated in  FIG. 2 ; see  FIG. 4  and  FIG. 5 ). 
     Each of the antenna connection terminals  220   a  to  220   d  is electrically connected to the circuit  250 . In the description below, when the antenna connection terminals  220   a  to  220   d  are not particularly distinguished from each other, the antenna connection terminals  220   a  to  220   d  are simply referred to as the antenna connection terminals  220 . The antenna connection terminals  220  are provided on the antenna mounting surfaces  211 . An antenna can be mounted to or removed from each antenna connection terminal  220 . Specifically, each antenna connection terminal  220  supports antennas of both of rod antennas  232  (see  FIG. 4 ) and planar antennas  231  (see  FIG. 5 ). 
     In general, the rod antenna  232  has characteristics in that it has no directivity or low directivity. The rod antenna  232  may be referred to as a rod antenna. In contrast, the planar antenna  231  has characteristics in that it has high directivity. The planar antenna  231  may be referred to as a patch antenna. 
       FIGS. 3A and 3B  are each a diagram illustrating a directional pattern of the planar antennas  231  according to an embodiment. As illustrated in  FIGS. 3A and 3B , the planar antenna  231  has high directivity with respect to a direction perpendicular to an antenna surface. 
     In the example illustrated in  FIG. 3A , among two planar antennas  231 , one planar antenna  231  is provided on one surface of the housing  210 , and the other planar antenna  231  is provided on the opposite surface of the housing  210 . In this manner, by arranging the directivities of the two planar antennas  231  in directions opposite to each other, the diversity effect can be achieved. 
     In the example illustrated in  FIG. 3B , two planar antennas  231  are provided on one surface of the housing  210 . In this manner, by arranging the directivities of the two planar antennas  231  in the same direction, a composite gain can be achieved. 
     As illustrated in  FIG. 2 , the connection antennas  230   a  to  230   d  are directly connected to the antenna connection terminals  220   a  to  220   d , respectively. In the description below, when the connection antennas  230   a  to  230   d  are not particularly distinguished from each other, the connection antennas  230   a  to  230   d  are simply referred to as the connection antennas  230 . The type of the connection antennas  230  is either the rod antennas  232  or the planar antennas  231 . 
     The following will mainly describe an example in which the connection antennas  230  are antennas of the same type. Note that a part of the connection antennas  230  may be the rod antennas  232 , and the rest of the connection antennas  230  may be the planar antennas  231 . 
     The external connection terminals  240   a  and  240   b  are electrically connected to the circuit  250 . In the description below, when the external connection terminals  240   a  and  240   b  are not particularly distinguished from each other, the external connection terminals  240   a  and  240   b  are simply referred to as the external connection terminals  240 . The external connection terminals  240  are provided on the installation surface  212 . 
     Specifically, the external connection terminal  240   a  is a terminal for transmitting and receiving data to and from the outside. There may be a plurality of external connection terminals  240   a . The external connection terminal  240   b  is a terminal for receiving power supply from the outside. 
     The circuit  250  includes various circuits and circuit boards housed in the housing  210 . The circuit  250  performs road-to-vehicle communication via the connection antennas  230  connected to the antenna connection terminals  220 . The circuit  250  may further perform road-to-road communication via the connection antennas  230 . The circuit  250  includes a communication circuit  251 , a control circuit  252 , an interface  253 , and a power circuit  254 . 
     The communication circuit  251  performs wireless communication (that is, road-to-vehicle communication) with the in-vehicle device  150  provided in the vehicle  100 . The communication circuit  251  may further perform road-to-road communication via the connection antennas  230 . 
     The communication circuit  251  converts a radio signal received by the connection antennas  230  into reception data, and outputs the reception data to the control circuit  252 . Further, the communication circuit  251  converts transmission data output by the control circuit  252  into a radio signal, and transmits the radio signal from the connection antennas  230 . 
     A wireless communication scheme of the communication circuit  251  may be a scheme in conformity to the standard of T109 of the Association of Radio Industries and Businesses (ARIB), a scheme in conformity to the standard of vehicle-to-everything (V2X) of the Third Generation Partnership Project (3GPP), and/or a scheme in conformity to the standard of a wireless local area network (LAN) such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 series. The communication circuit  251  may be configured to be capable of conforming to all of these communication standards. 
     The communication circuit  251  may support a plurality of frequency bands. The communication circuit  251  may include a first communication circuit  251   a  supporting a first frequency band, and a second communication circuit  251   b  supporting a second frequency band different from the first frequency band. The first frequency band and the second frequency band may be frequency bands of wireless communication schemes different from each other. For example, the first frequency band may be a frequency band in conformity to the standard of T109, and the second frequency band may be a frequency band in conformity to the standard of V2X. 
     The control circuit  252  controls various functions of the roadside apparatus  200 . The control circuit  252  includes at least one memory  252   b , and at least one processor  252   a  electrically connected to the memory  252   b . The memory  252   b  includes a volatile memory and a non-volatile memory, and stores information used for processing in the processor  252   a  and programs to be executed by the processor  252   a . The memory  252   b  corresponds to a storage. The processor  252   a  performs various types of processing by executing the programs stored in the memory  252   b.    
     The interface  253  is an interface for wired communication with an external apparatus. The interface  253  is electrically connected to the external connection terminal  240   a . The interface  253  may perform communication with the server  400 , another roadside apparatus  200 , the traffic light  300 , and/or a roadside camera via the external connection terminal  240   a.    
     The power circuit  254  converts a power voltage supplied from the external apparatus via the external connection terminal  240   b , and outputs the converted power voltage to each circuit. 
     Detailed Configuration of Roadside Apparatus 
     Next, detailed configurations of the roadside apparatus  200  according to an embodiment will be described. 
       FIG. 4  is a perspective view of the housing  210  seen from the installation surface  212  side regarding the roadside apparatus  200  to which the rod antennas  232  are connected.  FIG. 5  is a perspective view of the housing  210  seen from the installation surface  212  side regarding the roadside apparatus  200  to which the planar antennas  231  are connected.  FIG. 6  is a perspective view of the housing  210  seen from a front surface  213  side regarding the roadside apparatus  200  to which the rod antennas  232  are connected.  FIG. 7  is a perspective view of the housing  210  seen from the front surface  213  side regarding the roadside apparatus  200  to which the planar antennas  231  are connected. The front surface  213  is the opposite surface of the installation surface  212 . 
     As illustrated in  FIGS. 4 and 5 , the roadside apparatus  200  includes the housing  210  including the antenna mounting surface  211 , and the antenna connection terminals  220  that are provided on the antenna mounting surfaces  211  and support antennas of both of the rod antennas  232  and the planar antennas  231 . The area of the antenna mounting surface  211  is as large as or larger than the area of the planar antenna  231 . Antennas selected among the planar antennas  231  and the rod antennas  232  are connected as the connection antennas  230  to the antenna connection terminals  220 . 
     As described above, the area of the antenna mounting surface  211  is larger than the area of the planar antenna  231 , and antennas selected among the planar antennas  231  and the rod antennas  232  are connected to the antenna connection terminals  220 . Therefore, one roadside apparatus  200  can be used on several occasions depending on its purpose, for example, as the directional roadside apparatus and the omnidirectional roadside apparatus. As a result, the roadside apparatus  200  having high versatility that can be adapted to various road environments and purposes can be provided. 
     The housing  210  of the roadside apparatus  200  includes a plurality of antenna mounting surfaces  211  that are not coplanar, and the antenna connection terminals  220  are provided on each of the plurality of antenna mounting surfaces  211 . By connecting the antennas to each antenna mounting surface  211  in this manner, the diversity effect can be achieved. 
     Further, as illustrated in  FIG. 5 , when the planar antennas  231  are provided on each of the plurality of antenna mounting surfaces  211 , the directivities of the planar antennas  231  can be arranged in various directions. This allows for adaptation to various road environments and purposes. 
     Note that the number of antenna mounting surfaces  211  provided in the housing  210  may be one, or may be three or more. 
     A plurality of antenna connection terminals  220  are provided on each of the plurality of antenna mounting surfaces  211 .  FIGS. 4 and 5  illustrate examples in which two antenna connection terminals  220   a  and  220   b  are provided on an antenna mounting surface  211   a , and two antenna connection terminals  220   c  and  220   d  are provided on an antenna mounting surface  211   b . Note that the number of antenna connection terminals  220  provided in each antenna mounting surface  211  may be one, or may be three or more. 
     By providing a plurality of antenna connection terminals  220  in each of the plurality of antenna mounting surfaces  211 , a plurality of antennas can be connected to each antenna mounting surface  211 . Therefore, a composite gain can be enhanced. 
     In the example illustrated in  FIG. 4 , four rod antennas  232   a  to  232   d  are connected to four antenna connection terminals  220   a  to  220   d . The extension direction of each rod antenna  232  is perpendicular to the antenna mounting surface  211 . 
     In contrast, in the example illustrated in  FIG. 5 , four planar antennas  231   a  to  231   d  are connected to four antenna connection terminals  220   a  to  220   d .  FIG. 5  illustrates an example in which the planar shape of each planar antenna  231  is a circle. However, the planar shape of each planar antenna  231  may be a rectangle. 
     The intervals of the antenna connection terminals  220  in the same antenna mounting surface  211  are set such that two planar antennas  231  can be provided on the same antenna mounting surface  211 . Further, the area of each antenna mounting surface  211  is as large as or larger than the total area of the two planar antennas  231  (see  FIG. 7 ). 
     The housing  210  further includes the installation surface  212  being a surface different from the plurality of antenna mounting surfaces  211 . The installation surface  212  is a surface facing a supporter that supports the roadside apparatus  200  in an installation state in which the roadside apparatus  200  is installed. Here, the supporter is, for example, a support  601  or an arm  602  (see  FIG. 8 , for example). 
     The external connection terminals  240  ( 240   a  and  240   b ) electrically connected to the circuit  250  are provided on the installation surface  212 . Specifically, an external connector  212   a  including the external connection terminals  240  is provided in a part of the region of the installation surface  212 . 
     By providing the external connection terminals  240  on the installation surface  212  being a surface different from the antenna mounting surface  211 , the external connection terminals  240  need not be provided on the plurality of antenna mounting surfaces  211 , and the planar antennas  231  can be more easily provided on the plurality of antenna mounting surfaces  211 . In other words, the area of each of the plurality of antenna mounting surfaces  211  can be reduced, and thus the housing  210  can be downsized. 
     In an embodiment, the housing  210  includes an antenna mounting surface  211   a  (first antenna mounting surface), and an antenna mounting surface  211   b  (second antenna mounting surface) located on the opposite side of the antenna mounting surface  211   a . First antenna connection terminals  220  (antenna connection terminals  220   a  and  220   b ) are provided on the antenna mounting surface  211   a . Second antenna connection terminals  220  (antenna connection terminals  220   c  and  220   d ) are provided on the antenna mounting surface  211   b.    
     In this manner, a distance between the connection antennas  230  of the first antenna connection terminals  220  (antenna connection terminals  220   a  and  220   b ) and the connection antennas  230  of the second antenna connection terminals  220  (antenna connection terminals  220   c  and  220   d ) can be increased. 
     Therefore, correlation between antennas can be lowered, and the diversity effect can thus be enhanced. Further, as illustrated in  FIG. 5 , when each connection antenna  230  is the planar antenna  231 , directivities can be arranged in directions opposite from each other. 
     The housing  210  further includes a heat sink  215  provided on a surface different from the plurality of antenna mounting surfaces  211 . In this manner, the heat sink  215  need not be provided on the plurality of antenna mounting surfaces  211 , and the planar antennas  231  can be more easily provided on the plurality of antenna mounting surfaces  211 . In other words, the area of each of the plurality of antenna mounting surfaces  211  can be reduced, and thus the housing  210  can be downsized. 
     Specifically, the heat sink  215  is provided at least on the installation surface  212 . In the examples illustrated  FIGS. 6 and 7 , the heat sink  215  is not provided on the front surface  213  side of the housing  210 . When the heat sink  215  is provided on the installation surface  212 , the heat sink  215  can be made less noticeable to people, and the aesthetic of the roadside apparatus  200  can thus be enhanced. 
     Note that  FIGS. 4 and 5  illustrate examples in which the heat sink  215  is provided only in a part of the region of the installation surface  212 . However, the heat sink  215  may be entirely provided in a region of the installation surface  212  other than that of the external connector  212   a.    
     Installation Example of Roadside Apparatus 
     Next, installation examples of the roadside apparatus  200  according to an embodiment will be described. 
       FIGS. 8 and 9  are each a diagram illustrating an installation example of the roadside apparatus  200  regarding the roadside apparatus  200  to which the rod antennas  232  are connected. 
     As illustrated in  FIGS. 8 and 9 , the roadside apparatus  200  is installed near the traffic light  300  supported by the support  601  and the arm  602 . In the example illustrated in  FIG. 8 , the roadside apparatus  200  is installed in the arm  602 . In the example illustrated in  FIG. 9 , the roadside apparatus  200  is installed in the support  601 . 
     When the rod antennas  232  are connected to the antenna connection terminals  220 , the roadside apparatus  200  is installed in a state in which the antenna mounting surface  211  is substantially parallel to a road surface of the road R. In other words, the roadside apparatus  200  is installed in a state in which the installation surface  212  and the front surface  213  are substantially perpendicular to the road surface of the road R. In this manner, the extension direction of each rod antenna  232  is also substantially perpendicular to the road surface of the road R. 
     By installing the roadside apparatus  200  in this manner, the directivity can be arranged uniformly in directions parallel to the road surface, for example, the horizontal direction. 
       FIG. 10  is a diagram illustrating a directional pattern of the roadside apparatus  200  when the roadside apparatus  200  to which the rod antennas  232  are connected is installed at an intersection. 
     As illustrated in  FIG. 10 , when the roadside apparatus  200  to which the rod antennas  232  are connected is installed at an intersection, the directional pattern of the roadside apparatus  200  covers the vicinity of the intersection, allowing the roadside apparatus  200  to perform road-to-vehicle communication with the vehicle  100  on each of the roads R 1  and R 2 . 
       FIG. 11  is a diagram illustrating an installation example of the roadside apparatus  200  regarding the roadside apparatus  200  to which the planar antennas  231  are connected. 
     As illustrated in  FIG. 11 , the roadside apparatus  200  is installed near the traffic light  300  supported by the support  601  and the arm  602 . In the example illustrated in  FIG. 11 , the roadside apparatus  200  is installed at the lower side of the arm  602 . 
     When the planar antennas  231  are connected to the antenna connection terminals  220 , the roadside apparatus  200  is installed in a state in which the antenna mounting surface  211  is substantially perpendicular to the road surface of the road R. In other words, the roadside apparatus  200  is installed in a state in which the installation surface  212  and the front surface  213  are substantially parallel to the road surface of the road R. In the example illustrated in  FIG. 11 , the front surface  213  faces the road surface. 
     By installing the roadside apparatus  200  in this manner, the high directivity of the planar antennas  231  can be arranged in directions parallel to the road surface, for example, the horizontal direction. 
       FIG. 12  is a diagram illustrating a directional pattern of the roadside apparatus  200  when the roadside apparatus  200  to which the planar antennas  231  are connected is installed at an intersection. 
     As illustrated in  FIG. 12 , when the roadside apparatus  200  to which the planar antennas  231  are connected is installed at an intersection such that the directivity of the roadside apparatus  200  is arranged in a direction of a specific road (the road R 2  in the example illustrated in  FIG. 12 ), the radio waves can be prevented from being transmitted to a road (the road R 1  in the example illustrated in  FIG. 12 ) that is not to be communicated with. 
     Outer Appearance Configuration Example of Roadside Apparatus 
     Next, outer appearance configuration examples of the roadside apparatus  200  according to an embodiment will be described. 
       FIGS. 13A and 13B  are each a diagram illustrating outer appearance configuration example 1 of the roadside apparatus  200  according to an embodiment.  FIG. 13A  is a perspective view of the roadside apparatus  200  regarding the roadside apparatus  200  to which the rod antennas  232  are connected.  FIG. 13B  is a perspective view of the roadside apparatus  200  regarding the roadside apparatus  200  to which the planar antennas  231  are connected. 
     As illustrated in  FIGS. 13A and 13B , in outer appearance configuration example 1, surfaces of the housing  210  of the roadside apparatus  200  other than the antenna mounting surfaces  211 , the installation surface  212 , and the front surface  213  are curved. 
     Further, the housing  210  of the roadside apparatus  200  includes a lid  260  that entirely covers the antenna mounting surfaces  211  provided with the connection antennas  230  and the like. 
     When the rod antennas  232  are connected as the connection antennas  230  to the antenna connection terminals  220 , as illustrated in  FIG. 13A , lids  261   a, b  ( 260 ) including protrusions according to the shape of the rod antennas  232  are mounted to the housing  210 . The lid  261   a  provided for the antenna mounting surface  211   a  includes two protrusions for two rod antennas  232 , and covers the antenna mounting surface  211   a  and the two rod antennas  232 . The lid  261   b  provided for the antenna mounting surface  211   b  also includes two protrusions for two rod antennas  232 , and covers the antenna mounting surface  211   b  and the two rod antennas  232 . In contrast, when the planar antennas  231  are connected as the connection antennas  230  to the antenna connection terminals  220 , as illustrated in  FIG. 13B , plate-like lids  262   a, b  ( 260 ) are mounted to the housing  210 . The lids  262   a, b  cover the antenna mounting surfaces  211   a, b  and the planar antennas  231 . 
     Owing to such a lid  260 , the antenna connection terminals  220  and the connection antennas  230  can be protected. Further, when the planar antennas  231  are connected to the antenna connection terminals  220 , the plate-like lid  260  is mounted to the housing  210 . Therefore, the whole roadside apparatus  200  can be downsized, and the aesthetic of the roadside apparatus  200  can be enhanced with the shape thereof being simplified. 
       FIGS. 14A and 14B  are each a diagram illustrating outer appearance configuration example 2 of the roadside apparatus  200  according to an embodiment.  FIG. 14A  is a perspective view of the roadside apparatus  200  regarding the roadside apparatus  200  to which the rod antennas  232  are connected.  FIG. 14B  is a perspective view of the roadside apparatus  200  regarding the roadside apparatus  200  to which the planar antennas  231  are connected. 
     As illustrated in  FIGS. 14A and 14B , in outer appearance configuration example 2, in the housing  210  of the roadside apparatus  200 , the heat sink  215  is entirely provided on surfaces other than the antenna mounting surfaces  211  In this manner, heat dissipation performance of the roadside apparatus  200  can be enhanced. Note that the housing  210  of the roadside apparatus  200  includes a lid  260  that covers the antenna mounting surfaces  211  provided with the connection antennas  230  and the like. 
     When the rod antennas  232  are connected as the connection antennas  230  to the antenna connection terminals  220 , as illustrated in  14 A, lids  261   a, b  ( 260 ) including protrusions according to the shape of the rod antennas  232  are mounted to the housing  210 . The lid  261   a  provided for the antenna mounting surface  211   a  includes two protrusions for two rod antennas  232 , and covers the antenna mounting surface  211   a  and the two rod antennas  232 . The lid  261   b  provided for the antenna mounting surface  211   b  also includes two protrusions for two rod antennas  232 , and covers the antenna mounting surface  211   b  and the two rod antennas  232 . In contrast, when the planar antennas  231  are connected to the antenna connection terminals  220 , as illustrated in  FIG. 14B , the plate-like lids  262   a, b  ( 260 ) are mounted to the housing  210 . The lids  262   a, b  cover the antenna mounting surfaces  211   a, b  and the planar antennas  231 . 
       FIGS. 15A and 15B  are each a diagram illustrating outer appearance configuration example 3 of the roadside apparatus  200  according to an embodiment.  FIG. 15A  is a perspective view of the roadside apparatus  200  regarding the roadside apparatus  200  to which the rod antennas  232  are connected.  FIG. 15B  is a perspective view of the roadside apparatus  200  regarding the roadside apparatus  200  to which the planar antennas  231  are connected. 
     As illustrated in  FIGS. 15A and 15B , in outer appearance configuration example 3, the housing  210  of the roadside apparatus  200  includes a lid  260  that covers the antenna mounting surfaces  211  provided with the connection antennas  230  and the like, and four lids  260  provided for four antenna connection terminals  220  (four connection antennas  230 ). Each lid  260  has a circular planar shape. 
     When the rod antennas  232  are connected to the antenna connection terminals  220 , as illustrated in  FIG. 15A , lids  261   a, b  are provided for the rod antennas  232 . The lids  261   a, b  each includes a protrusion for the rod antenna  232 , and covers the antenna mounting surface  211   a  and the rod antenna  232 . Lids  261   c, d  are provided for the opposite rod antennas  232 . The lids  261   c, d  each include a protrusion for the rod antenna  232 , and cover the antenna mounting surface  211   b  and the rod antenna  232 . In contrast, when the planar antennas  231  are connected to the antenna connection terminals  220 , as illustrated in  FIG. 15B , plate-like lids  262   a, b  ( 260 ) are mounted to the housing  210 , and the lids  262   a, b  cover the antenna mounting surface  211   a  and the planar antennas  231 . Further, plate-like lids  262   c, d  ( 260 ) are mounted to the housing  210 , and the lids  262   c, d  cover the antenna mounting surface  211   b  and the planar antennas  231 . 
     Other Embodiments 
     The control circuit  252  may perform adaptive array control of dynamically changing directivity by using the plurality of connection antennas  230  connected to the plurality of antenna connection terminals  220 . In particular, the control circuit  252  may perform the adaptive array control when each connection antenna  230  is the rod antenna  232 . The adaptive array control includes at least one of beamforming, in which directivity (beam) is arranged in a direction of arrival of a desired wave, and null steering, in which nulls of directivity are arranged in a direction of arrival of an interference wave. By dynamically changing the directivity in this manner, communication quality of road-to-vehicle communication can be enhanced. 
     The housing  210  of the roadside apparatus  200  may include three or more antenna mounting surfaces  211 . For example, all of the surfaces other than the installation surfaces  212  and the front surface  213  may be the antenna mounting surfaces  211 . 
     The roadside apparatus  200  may support a plurality of frequency bands. Specifically, among the plurality of connection antennas  230  connected to the plurality of antenna connection terminals  220 , a part of the connection antennas  230  may be antennas for the first frequency band, and the rest of the connection antennas  230  may be antennas for the second frequency band different from the first frequency. 
     As illustrated in  FIG. 2 , the circuit  250  includes the first communication circuit that is electrically connected to the part of the connection antennas  230  and supports the first frequency band, and the second communication circuit that is electrically connected to the rest of the connection antennas  230  and supports the second frequency band. In this manner, the frequency bands of both of the first frequency band and the second frequency band can be supported, and versatility of the roadside apparatus  200  can thus be enhanced. 
       FIG. 16  is a diagram illustrating the roadside apparatus  200  according to another embodiment. As illustrated in  FIG. 16 , in the housing  210  of the roadside apparatus  200 , four surfaces other than the installation surfaces  212  and the front surface  213  are antenna mounting surfaces  211   a  to  211   d . Planar antennas  231   a  and  231   b  are provided on the antenna mounting surface  211   a , planar antennas  231   c  and  231   d  are provided on the antenna mounting surface  211   b , a planar antenna  231   e  is provided on the antenna mounting surface  211   c , and a planar antenna  231   f  is provided on the antenna mounting surface  211   d.    
     Further, the roadside apparatus  200  supports the frequency bands of both of the first frequency band (for example, 760 MHz) and the second frequency band (for example, 5.9 GHz).  FIG. 16  illustrates an example in which the connection antennas  230  are the planar antennas  231 . Among the plurality of planar antennas  231   a  to  231   f , a part of the planar antennas  231  ( 231   b ,  231   d ,  231   e , and  231   f ) are antennas for the first frequency band, and the rest of the planar antennas  231  ( 231   a  and  231   c ) are antennas for the second frequency band. 
     A program causing a computer to execute each of the processes performed by the in-vehicle device  150  or the roadside apparatus  200  may be provided. The program may be recorded in a computer-readable medium. Use of the computer-readable medium enables the program to be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. 
     In addition, circuits for executing the processes to be performed by the in-vehicle device  150  or the roadside apparatus  200  may be integrated, and at least part of the in-vehicle device  150  or the roadside apparatus  200  may be configured as a semiconductor integrated circuit (a chipset or an SoC). 
     Embodiments have been described above in detail with reference to the drawings, but specific configurations are not limited to those described above, and various design modifications can be made without departing from the gist of the present disclosure.