JP2010140352A - Radio communication system - Google Patents

Abstract

[PROBLEMS] To reduce the construction range of an electromagnetic wave absorber for unnecessary radio waves, to reduce maintenance costs, and to prevent communication with a mobile station in an unexpected location, thereby preventing erroneous processing. A wireless communication system that can be prevented is provided.
By arranging two radio wave emission source detection devices 18a and 18b for detecting the position of the radio wave emission source on both sides of a roadside radio device 16, the arrival direction and distance (position of the radio wave emission source) of the radio wave can be determined. It is detected and judged whether the radio wave from the vehicle-mounted device in the own lane, the unnecessary radio wave from the adjacent lane, or the unnecessary radio wave from the adjacent lane reflected on the vehicle in the own lane, and the roadside radio device 16 and the vehicle Whether or not the communication with the device 12 can be continued is determined.
[Selection] Figure 1

Description

  The present invention relates to a radio communication system suitable for use in, for example, an ETC system (toll road automatic toll collection system) that performs toll collection on a toll road in a radio communication system using narrow area radio communication.

For example, an ETC system (toll road automatic toll collection system) is known as a wireless communication system using narrow area wireless communication (DSRC). As is well known, an ETC system includes a mobile station (on-vehicle device) mounted on a vehicle (automobile) that is a moving body, and data is transmitted by radio communication using a microwave with a base station installed on the ground. Toll collection processing is performed by exchanging.
In such an ETC system using narrow area wireless communication, a base station forms a radio communication radio wave area with a mobile station using a narrow directional antenna that is characteristic of narrow area wireless communication (for example, patents) Reference 1).

Further, in an ETC system using narrow area wireless communication, billing processing is performed by performing communication within a limited range using the characteristics of DSRC's narrow area wireless communication. However, due to the structure of the toll booth or the radio wave reflection of the vehicle, the radio wave leaks to an unexpected place, and communication is performed at an unexpected place.
Therefore, conventionally, in order to prevent this, an electromagnetic wave absorber is installed to prevent unnecessary reflection of radio waves (see, for example, Patent Document 2).
JP 2005-229300 A JP 2001-134895 A

  The characteristics of radio wave reflection in 5.8 GHz band DSRC narrow-band radio communications used in ETC systems are described. DSRC radio waves are relatively straight ahead, and their characteristics are used to make roadside radio equipment (base stations). The roadside antenna can form a radio wave communication area (wireless communication radio wave area) that can be called a radio wave beam. However, since metals such as road surfaces, structures, and vehicles have a property of reflecting radio waves, DSRC radio waves that are originally narrow-area wireless communication may fly to another place due to reflection.

  The vehicle-mounted device (mobile station) reacts to the unexpected radio wave that has arrived and emits a response radio wave. The radio waves have the property of returning to the roadside radio apparatus following the same path as the radio waves from the roadside radio apparatus. For example, in the shape of the rear part of a tank truck, the radio waves from the roadside radio apparatus are reflected to the adjacent lane. When the vehicle arrives at the vehicle-mounted device mounted in the vehicle, the radio wave of the vehicle-mounted device that responds to it is reflected at the rear part of the same tanker vehicle by turning back the radio wave path from the road-side wireless device and reaches the road-side wireless device. On the contrary, it is difficult to receive the on-board unit radio waves that are returned to the roadside antenna that emits the radio waves with another reception-only antenna that is slightly shifted laterally.

  As described above, the prevention of the reflection of the radio wave by the radio wave absorber can prevent the radio wave reflection of the structure, but it cannot prevent the event that the vehicle leaks into the adjacent lane due to the radio wave reflection of the vehicle. In addition, the radio wave absorber itself is very expensive, has a service life, and becomes a burden on the operator as a maintenance member. Furthermore, since the reflection of radio waves occurs randomly depending on the shape of the vehicle, the installation range and location of the radio wave absorber cannot be specified, and it is attached to a dark cloud, but the effect is not known.

  Therefore, the present invention can reduce the construction range of the radio wave absorber for unnecessary radio waves, reduce the maintenance cost, and prevent communication with a mobile station in an unexpected location. An object of the present invention is to provide a wireless communication system capable of preventing erroneous processing.

  A wireless communication system according to the present invention includes a base station disposed so as to form a wireless communication radio wave range with respect to a predetermined position of a moving path on which a mobile body moves, and mounted on the mobile body, When entering, a mobile station that starts communication with the base station by transmitting a response radio wave to the interrogation radio wave from the base station, disposed on both sides of the base station, and a radio wave emission source And at least two radio wave emission source detection means for detecting the position of the radio wave emission source, and a determination means for judging whether or not the communication between the base station and the mobile station can be continued based on the detection results of the radio wave emission source detection means. is doing.

  According to the present invention, it is possible to reduce the construction range of an electromagnetic wave absorber for unnecessary radio waves, it is possible to reduce maintenance costs, and prevent communication with a mobile station in an unexpected place, thereby A wireless communication system capable of preventing erroneous processing can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a configuration of an ETC system using narrow area wireless communication as a wireless communication system according to an embodiment of the present invention. In FIG. 1, a vehicle (for example, an automobile) 11 as a moving body is equipped with an in-vehicle device 12 as a mobile station. For example, a toll collection lane (movement path) 13 of a toll gate on a toll road (highway). Is assumed to travel in the direction of the arrow in the figure. On both sides of the toll collection lane 13, islands 14 and 15 are provided, respectively.

  The toll collection lane 13 includes an ETC dedicated lane dedicated to ETC vehicles, a mixed lane that can be processed by mixing ETC vehicles and general vehicles (non-ETC vehicles), a general dedicated lane only for general vehicles, etc. In order to make the explanation easy to understand, a case of one ETC dedicated lane will be described.

  A roadside radio device 16 serving as a base station is disposed at an upper portion of the toll collection lane 13 at a predetermined position and at a substantially central portion in a direction orthogonal to the moving direction of the vehicle 11. The roadside radio device 16 includes a roadside antenna for performing communication with the vehicle-mounted device 12. As shown in the figure, the roadside radio device 16 is located on the upstream side of the roadside radio device 16 on the toll collection lane 13. Is arranged.

  On both side portions of the roadside apparatus 16 in the direction orthogonal to the moving direction of the vehicle 11, radio wave emission source detection devices 18 a and 18 b as radio wave emission source detection means are arranged. The radio wave emission source detection devices 18a and 18b detect the position of the radio wave emission source, and will be described in detail later.

  The radio wave emission source detection devices 18a and 18b are each connected to a determination unit 19 as a determination unit. Based on the detection results of the radio wave emission source detection devices 18a and 18b, the determination unit 19 determines whether the response radio wave from the vehicle-mounted device 12 in the radio communication radio wave zone 17 is a response radio wave from the other, or the roadside radio device. 16 to determine whether or not the communication between the vehicle-mounted device 12 and the vehicle-mounted device 12 can be continued.

  The determination unit 19 is connected to a control unit 20 as a control unit. For example, the control unit 20 is configured mainly by a CPU (Central Processing Unit) or the like, and controls communication processing in the roadside apparatus 16 based on the determination result of the determination unit 19 or collects charges. The details will be described later.

  With such a configuration, normally, the vehicle 11 (the vehicle-mounted device 12) enters the wireless communication radio wave zone 17, and the response radio wave from the vehicle-mounted device 12 to the interrogation radio wave from the roadside radio device 16 is the radio communication radio wave range. Each of them can be received by the roadside apparatus 16 forming the circuit 17.

  However, as shown in FIG. 2, for example, the interrogation radio wave E1 from the roadside radio device 16 is reflected on the side surface of the vehicle 11 in the radio communication radio wave zone 17, and the vehicle 11a that normally travels in the adjacent lane should not communicate. In response to the vehicle-mounted device 12a mounted on the vehicle, the response radio wave E2 from the vehicle-mounted device 12a responding to the reflected vehicle is reflected on the side surface of the vehicle 11 through the same route and reaches the roadside device 16.

  Conversely, the radio wave of the vehicle-mounted device 12a that returns to the roadside apparatus 16 that has emitted the radio wave is difficult to receive with another reception-specific antenna that is slightly shifted laterally. By using this, it is possible to determine that the on-vehicle device 12 a is an on-vehicle device outside the radio communication radio wave range 17.

  The radio wave emission source detection devices 18a and 18b use, for example, the radio wave emission source detection portion of the radio wave emission source display device disclosed in Japanese Unexamined Patent Publication No. 2007-17393. explain. The details are described in Japanese Patent Application Laid-Open No. 2007-17393, so please refer to it.

  In FIG. 3, the radio wave emission source detection devices 18 a and 18 b detect the angle formed by the radio wave reception unit 31 that receives the radio wave emitted by the radio wave emission source T, the front direction of the vehicle 11, and the surface on which the radio wave reception unit 31 is disposed. And an azimuth distance measuring unit 33 that measures the position (for example, distance and direction) of the radio wave emission source T based on the received signal received by the radio wave receiving unit 31.

  The radio wave receiving unit 31 includes a reference antenna unit 31a and an array antenna unit 31b. The reference antenna unit 31a and the array antenna unit 31b are arranged in the vicinity. For example, the reference antenna unit 31a is configured by one reference antenna element A1, and the array antenna unit 31b is configured by a plurality of array antenna elements B1 to Bn. .

  The reference antenna element A1 and the array antenna elements B1 to Bn are provided, for example, on one plane perpendicular to the horizontal plane, and the array antenna elements B1 to Bn are, for example, on a one-dimensional straight line at a certain interval. Is arranged. The array antenna elements B1 to Bn can also be arranged at a certain interval in two dimensions, vertical and horizontal.

  Further, the surface on which the reference antenna element A1 and the plurality of array antenna elements B1 to Bn are arranged is configured to be rotatable in the azimuth direction, for example. For example, the angle sensor 32 detects the angle formed by the front direction of the vehicle 11 indicated by the arrow Y and the surface on which the reference antenna element A1 and the plurality of array antenna elements B1 to Bn are arranged.

  The azimuth distance measurement unit 33 includes a frequency conversion unit 34, an A / D conversion unit 35, and a signal processing unit 36. That is, the received signal received by the radio wave receiving unit 31 is sent to the frequency converting unit 34 and subjected to frequency conversion. In this case, the connection between the radio wave receiver 31 and the frequency converter 34 may be configured such that the respective array antenna elements B1 to Bn are connected in parallel to the frequency converter 34, or the array antenna elements B1 to Bn are connected to each other. One array antenna element can be connected in order by switching with a switch or the like.

  The reception signal frequency-converted by the frequency converter 34 is digitized by the A / D converter 35 and converted into reception data. The reception data converted by the A / D conversion unit 35 is sent to the signal processing unit 36.

  The signal processing unit 36 includes a DSP (Digital Signal Processor) or CPU (Central Processing Unit) that processes received data, and a storage unit that stores received data, for example, a semiconductor memory or a hard disk. The signal processing unit 36 performs, for example, radio holography processing using Fresnel approximation on the received data, and obtains the position of the radio wave emission source T, for example, the distance and direction of the radio wave emission source T. The direction of the radio wave emission source T, that is, the arrival direction of the radio wave is determined by using the antenna angle information between the front of the vehicle 11 and the radio wave receiving unit 31 obtained from the angle sensor 32. decide.

According to the configuration described above, position information of the radio wave emission source T (for example, distance information and direction information of the radio wave emission source T) can be obtained.
In addition, radio waves emitted from the radio wave emission source T are received by a plurality of antennas, a holographic reproduction image using Fresnel approximation is obtained based on reception data obtained from the reception signals, and radio waves are emitted from a position where the value is maximum. The distance of the source T is specified. Therefore, it is not necessary to use a plurality of direction finding sensors and the like, and the configuration is simplified.

  Here, a method for detecting the distance and direction of the radio wave emission source T in the signal processing unit 36 of the azimuth distance measuring unit 33 will be described. In this method, arithmetic processing is performed using the reception data DR obtained from the reception signal of the reference antenna element A1 and the reception data D1 to DN obtained from the reception signals of the array antenna elements B1 to Bn.

  This calculation process is performed using, for example, parameters as shown in FIG. For example, the distance to the radio wave emission source T is z, the axis orthogonal to the z axis connecting the radio wave reception unit 31 and the radio wave emission source T is the x axis, the x coordinate of the reference antenna element A1 is Xref, and n array antenna elements The coordinates of B1 to Bn are assumed to be X1, X2,.

  First, the received data DR based on the received signal of the reference antenna element A1 is Fourier transformed to obtain its complex conjugate. Further, the received data D1 to DN based on the received signals of the array antenna elements B1 to Bn are Fourier transformed. Next, the result of Fourier transform of the received data DR and the result of Fourier transform of the received data D1 to DN are multiplied and added in the frequency range of the radio wave emitted from the radio wave emission source T, and the correlation matrix u is added. (Xn) is obtained.

  Next, the calculation result u (Xn) is substituted into an expression using Fresnel approximation to obtain a holographic reproduction image of the radio wave emission source T. Next, the position of the radio wave emission source T is specified from the coordinates at which the holographic reproduction image becomes maximum, and the distance of the radio wave emission source T and the direction of the radio wave emission source T are detected. Data indicating the distance and direction of the radio wave emission source T becomes position information (coordinate information) indicating the position of the radio wave emission source T and is sent to the determination unit 19.

Next, the operation of such a configuration will be described with reference to the flowchart shown in FIG.
First, a polling signal (question radio wave) is transmitted from the roadside apparatus 16 (step S1). Next, the determination unit 19 determines whether or not the position information of the radio wave emission source is received from the radio wave emission source detection device 18a (step S2), and receives the position information of the radio wave emission source from the radio wave emission source detection device 18a. If so, the position information is temporarily stored (step S3).

  Next, the determination unit 19 determines whether or not the position information of the radio wave emission source is received from the radio wave emission source detection device 18b (step S4), and receives the position information of the radio wave emission source from the radio wave emission source detection device 18b. If so, the position information is temporarily stored (step S5).

  Next, the determination unit 19 compares the temporarily stored position information from the radio wave emission source detection device 18a with the temporarily stored position information from the radio wave emission source detection device 18b, and determines whether or not they match. (Step S6) When the two match, it is determined that the radio wave emission source is the vehicle-mounted device 12 existing in the radio communication radio wave zone 17, and subsequent communication with the vehicle-mounted device 12 is permitted (Step S7). ), The process returns to step S1. That is, in this case, subsequent communication with the vehicle-mounted device 12 is permitted as normal.

  If the position information of the radio wave emission source is not received from the radio wave emission source detection device 18a in step S2, the position information of the radio wave emission source is not received from the radio wave emission source detection device 18b in step S4, or the both position information in step S6. If they do not match, the determination unit 19 determines that the radio wave emission source is due to unnecessary reflection, rejects subsequent communication with the vehicle-mounted device 12 in the radio communication radio wave range 17 (step S8), and proceeds to step S1. Return. That is, in this case, subsequent communication with the vehicle-mounted device 12 is rejected as an abnormality.

  The control unit 20 controls the roadside apparatus 16 to start communication with the vehicle-mounted device 12 when the determination unit 19 obtains a determination result indicating that the subsequent communication with the vehicle-mounted device 12 is permitted as normal. When the determination unit 19 obtains a determination result indicating that the subsequent communication with the vehicle-mounted device 12 is rejected as an abnormality, the roadside wireless device 16 is controlled not to communicate with the vehicle-mounted device 12.

  6 and 7 schematically show an image of determination by the determination unit 19 described above. FIG. 6 shows the case where the vehicle-mounted device 12 is in the radio communication radio wave range 17 (own lane), and FIG. Is the case.

Hereinafter, a specific example will be described.
FIG. 8 shows a case of radio waves from the vehicle-mounted device 12 in the toll collection lane 13 (own lane). In this example, the direct wave from the vehicle-mounted device 12 returns not only to the roadside wireless device 16 but also to both the left and right radio wave emission source detection devices 18a and 18b. The position information (coordinate information) of the radio wave emission sources detected by the two radio wave emission source detection devices 18a and 18b is a mirror surface object, but indicates the same position of the vehicle-mounted device 12. Therefore, in this case, it is determined as normal and communication is permitted.

  FIG. 9 shows a case of radio waves from the vehicle-mounted device 12a in the lane (adjacent lane) adjacent to the toll collection lane 13 (own lane). In this example, the radio wave from the vehicle-mounted device 12a in the adjacent lane is reflected by the vehicle 11 in the own lane and received only by the left radio wave emission source detection device 18b, for example, and the position of the radio wave emission source is detected (or In this case, it is determined as unnecessary reflection and communication is rejected.

  FIG. 10 shows the case of radio waves reflected from the vehicle 11 in the own lane by radio waves from the vehicle-mounted device 12a in the lane (adjacent lane) adjacent to the toll collection lane 13 (own lane). In this example, the shape of the vehicle 11 that reflects the radio wave is complicated, and the radio wave reflection position is different regardless of which of the left and right radio wave emission source detection devices 18a and 18b receives the radio wave. Judgment is made and communication is refused.

  Thus, by arranging the two radio wave emission source detection devices 18a and 18b for detecting the position of the radio wave emission source on both sides of the roadside radio device 16, the arrival direction and distance of the radio wave (position of the radio wave emission source) can be determined. It is detected and judged whether the radio wave from the vehicle-mounted device in the own lane, the unnecessary radio wave from the adjacent lane, or the unnecessary radio wave from the adjacent lane is reflected on the vehicle in the own lane, and the roadside radio device 16 and the vehicle-mounted By determining whether or not the communication with the device 12 can be continued, it is possible to reduce the construction range of the radio wave absorber for unnecessary radio waves, and to reduce the maintenance cost. Further, it is possible to prevent communication with the vehicle-mounted device in an unexpected place, thereby preventing erroneous processing such as erroneous charging.

In the above embodiment, a case where a total of two radio wave emission source detection devices are installed on both sides of the roadside radio device has been described. However, the present invention is not limited to this, and radio wave emission source detection is performed. Even if two or more apparatuses, for example, two radio wave emission source detection apparatuses are installed on both sides of the roadside apparatus, a total of four apparatuses can be similarly implemented.
Also, the radio wave emission source detection device is not limited to the one shown in the above embodiment, and may be one that detects the position of the radio wave emission source by another method.

The schematic diagram which shows schematically the structure of the ETC system as a radio | wireless communications system which concerns on embodiment of this invention. The schematic diagram explaining a response wave from the vehicle equipment of an adjacent lane reaching the roadside radio apparatus through the same path | route which responded with respect to the inquiry radio wave from the roadside radio apparatus reflected in the vehicle of the own lane. The block diagram which shows roughly the structure of a radio wave emission source detection apparatus. The figure for demonstrating the parameter used for specification of the position of a radio wave emission source. The flowchart explaining operation | movement. The figure which shows schematically the image of the determination in the determination part in case an onboard equipment is a self lane. The figure which shows schematically the image of the determination in the determination part in the case of unnecessary reflection. The schematic diagram explaining the specific example in the case of the electromagnetic wave from the onboard equipment of an own lane. The schematic diagram explaining the specific example in the case of the electromagnetic wave from the vehicle equipment of an adjacent lane. The schematic diagram explaining the specific example in the case of the electromagnetic wave reflected on the vehicle of the own lane with the electromagnetic wave from the vehicle equipment of an adjacent lane.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Vehicle (mobile body) 12 ... Onboard equipment (mobile station), 13 ... Toll collection lane (movement path), 16 ... Roadside radio | wireless apparatus (base station), 17 ... Radio communication radio sphere, 18a, 18b ... Radio wave emission Source detection device (radio wave emission source detection means), 19 ... determination section (determination means), 20 ... control section, E1 ... interrogation radio wave, E2 ... response radio wave.

Claims (3)

A base station disposed so as to form a radio communication radio wave range for a predetermined position of a moving path on which the moving body moves;
A mobile station that is mounted on the mobile body and starts communication with the base station by transmitting a response radio wave to the interrogation radio wave from the base station when entering the radio communication radio wave range; and
At least two radio wave emission source detecting means arranged on both sides of the base station for detecting the position of the radio wave emission source;
Based on each detection result of the radio wave emission source detection means, a determination means for determining whether or not to continue communication between the base station and the mobile station,
A wireless communication system comprising:   The base station is installed at a substantially central portion of the moving path in a direction orthogonal to the moving direction of the moving body, and the radio communication radio wave area is formed upstream of the base station on the moving path. The radio communication system according to claim 1, wherein the radio wave emission source detecting means is installed on both sides of the base station in a direction orthogonal to a moving direction of the moving body.   When each detection result of the radio wave emission source detection means indicates the same position, the determination means determines that the radio wave emission source is a mobile station existing in the radio communication radio wave range and Allow continuation of communication with the base station, otherwise, determine that the radio wave emission source is not a mobile station existing in the radio communication radio wave range, and between the mobile station and the base station The wireless communication system according to claim 1, wherein continuation of communication is rejected.

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