JP3589060B2 - Roadside-vehicle communication in-vehicle device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a road-vehicle communication in-vehicle device that receives a radio beacon signal or an optical beacon signal transmitted from a road station installed along a road and acquires information included in the beacon signal.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a road station (hereinafter referred to as a beacon) that outputs radio waves or light including such information in order to provide a driver of a vehicle running on a road with location information and road traffic information such as traffic congestion in real time. A road-to-vehicle communication system has been proposed in which a vehicle is installed along a road, and a road-to-vehicle communication is performed between these beacons and a communication device mounted on the vehicle. A road traffic information system called VICS (Vehicle Information and Communication System) has already started operation.
[0003]
In the above-mentioned VICS, a radio beacon for transmitting microwave band radio waves or an optical beacon for transmitting infrared rays is provided at predetermined intervals along a road. The radio beacon is mainly installed on an expressway, and its communication area is relatively wide, about 70 to 100 m, so that one-way communication from the radio beacon to a road-to-vehicle communication device mounted on a vehicle is possible. On the other hand, optical beacons are mainly installed on general roads, and their communication area is relatively small, about 5 m, so that bidirectional communication between the optical beacon and a road-to-vehicle communication device mounted on a vehicle is possible. I have. In VICS, FM multiplex broadcasting can be used in addition to these beacons.
[0004]
[Problems to be solved by the invention]
In such a road-to-vehicle communication system, the road-to-vehicle communication device mounted on the vehicle determines the reception level of the radio beacon signal transmitted from the radio beacon when determining whether the vehicle is located within the radio beacon communication area. It is configured to use. FIG. 8A shows the relationship between the position of the vehicle and the reception level (for example, the received input power) of the radio wave beacon signal received by the road-to-vehicle communication device in this configuration. That is, the road-to-vehicle communication device determines that the reception level of the radio beacon signal is within the communication area of the radio beacon when the reception level of the radio beacon signal is equal to or higher than a preset reference value, and the reception level of the radio beacon signal is lower than the reference value. In such a case, it is determined that it is out of the communication area of the radio wave beacon. According to this configuration, it is possible to detect a communication area by a simple process of level comparison, thereby achieving high-speed processing and stable reception of a radio wave beacon signal.
[0005]
However, the road-vehicle communication device having the above-described conventional configuration has a precondition that only one radio beacon exists in one communication area, that is, a continuous area where the reception level of the radio beacon signal is equal to or higher than the reference value. The design was based on that. That is, after the road-vehicle communication device determines that the vehicle has entered the communication area and once obtains the radio beacon signal, the radio beacon signal received until the vehicle leaves the communication area after that is obtained from the same radio beacon. It was discarded because it was considered.
[0006]
Therefore, for example, as shown in FIG. 8B, there is an area (around the point B in the figure) that overlaps the radio beacon signals transmitted from the two radio beacons 1a and 1b arranged close to each other, and When the reception level of the radio wave beacon signal in the overlapping area has a level equal to or higher than the reference value, the road-to-vehicle communication device effectively activates only the radio wave beacon signal received earlier of the radio beacons 1a and 1b. I was capturing. For this reason, the other radio beacon signal is invalidated, and information from the invalidated radio beacon is not transmitted to the driver.
[0007]
Furthermore, when VICS was started, the number of installed radio beacons and optical beacons was small, and the installation targets of each beacon were, in principle, expressways for radio beacons and general roads for optical beacons. Both beacons were set apart. Therefore, the communication areas of both beacons rarely approached or overlapped. Therefore, the conventional road-to-vehicle communication device is configured to preferentially receive and process a beacon signal in an area in which a radio beacon communication area or an optical beacon communication area has entered earlier.
[0008]
However, in the situation where the number of installed radio wave beacons and optical beacons has increased dramatically with the expansion of VICS in recent years, for example, in the vicinity of the area where leaked radio waves from radio beacons installed on elevated roads arrive, there are other In many cases, road beacons are installed. Although regulations and guidelines have been established for radio wave beacon leakage, it is difficult to completely eliminate radio wave leakage. In particular, it is inevitable that radio waves leak at places where roads cross over and over in parallel.
[0009]
In such a case, when the road-vehicle communication device having the above-described conventional configuration is used, there is a possibility that the reception processing of the optical beacon signal may be hindered by the leaked radio wave from the radio beacon. For example, as shown in FIG. 9, a general road 4 on which an optical beacon 3 is installed is laid under an elevated road 2 on which an electric wave beacon 1 is installed. When the communication area is close to or overlapping with the communication area, when the road-vehicle communication device mounted on the vehicle 5 traveling on the general road 4 detects the communication area of the radio beacon signal before the communication area of the optical beacon signal, Until the processing of the radio wave beacon data ends, the reception processing of the optical beacon signal cannot be performed. As a result, there have been situations where the information from the optical beacon 3 is not transmitted to the driver or the transmission is delayed.
[0010]
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to arrange a plurality of radio beacons or optical beacons in close proximity to each other so that their communication areas are close to each other or overlap. Even in this case, an object of the present invention is to provide a road-vehicle communication in-vehicle device capable of correctly receiving a beacon signal to be received and reliably obtaining necessary information.
[0011]
[Means for Solving the Problems]
According to the road-vehicle communication in-vehicle device according to the first aspect, when a radio beacon signal is transmitted from the road station, the receiving means receives the radio beacon signal, and the radio beacon data detecting means outputs the radio beacon signal to the received radio beacon signal. On the other hand, processing such as demodulation is performed to detect radio wave beacon data. The radio wave reception level detecting means detects the reception level of the received radio wave beacon signal. When the reception level is equal to or higher than the preset reference level, the data processing means determines that the vehicle is in a communication area of any radio beacon (detects the communication area), Based on the detected radio beacon data, identify the road station transmitting the radio beacon signal, and obtain information transmitted from each of the identified road stations, When entering a communication area where radio waves from different road stations can be received while maintaining the reception level at or above a preset reference level, each time a different road station is identified, the radio beacon data is used. Information transmitted from each road station identified by It is supposed to.
[0012]
Therefore, as a result of the plurality of radio beacons being installed close to each other, the radio beacon signals transmitted from each radio beacon overlap when the reception level of the radio beacon signal is viewed, and the radio beacon signals constitute one communication as a whole. Even in the case where an area is formed, the data processing means always identifies the road station transmitting the radio wave beacon signal in the communication area, and each time a different road station is identified, the data processing unit transmits the signal from each road station. Get the information to be sent. This makes it possible to acquire information transmitted from the radio beacon without missing it and transmit it to the driver, provided that the incoming radio beacon signal has a reception level higher than the reference level. Become.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
Hereinafter, a first embodiment in which the road-vehicle communication in-vehicle device of the present invention is applied to a VICS (road traffic information system) will be described with reference to FIGS. 1 to 5.
As described in the section of the related art, the VICS uses radio wave beacons and optical beacons installed at predetermined intervals along the road (both corresponding to the road station in the present invention) to provide location information along with IDs and beacon numbers. And a system for transmitting road traffic information. On the vehicle side, such information can be received in real time using a road-to-vehicle communication in-vehicle device. In this case, one-way communication is performed from the radio beacon to the road-vehicle communication in-vehicle device, and bidirectional communication is performed between the optical beacon and the road-vehicle communication in-vehicle device.
[0020]
FIG. 1 schematically shows an electrical configuration of a road-vehicle communication in-vehicle device according to the present invention by using functional blocks. In FIG. 1, the road-vehicle communication in-vehicle device 11 includes an antenna unit 12 and a transmission / reception unit 13. The antenna unit 12 receives a radio beacon signal from a radio beacon and transmits and receives an optical beacon signal to and from an optical beacon. The transmission / reception unit 13 acquires information included in the radio wave beacon signal and the optical beacon signal and transfers the acquired information to an external device such as a car navigation system, and generates an optical beacon signal including vehicle identification information and the like to generate the antenna unit 12. To be forwarded to.
[0021]
The antenna unit 12 is a front part of the vehicle interior such as an upper part of an instrument panel in a vehicle interior, an upper part of a windshield, a rear part of a rearview mirror, and a transmission antenna of a radio beacon installed on a road and an optical beacon light emitting and receiving device. It is installed in a position where it can be seen from the outside. The transmission / reception unit 13 is installed in a place that does not disturb the occupant, such as in a trunk or below a seat.
[0022]
The antenna unit 12 includes an antenna 13, a high-frequency receiving unit 14, a light emitting and receiving unit 15, a photoelectric conversion unit 16, and a multiplexing / demultiplexing unit 17. Among them, the antenna 13 and the high-frequency receiving unit 14 as receiving means receive microwave radio waves transmitted from the radio beacon, and output the received radio beacon signal to the multiplexing / demultiplexing unit 17. Similarly, the light emitting / receiving unit 15 and the photoelectric conversion unit 16 as receiving means receive an optical (infrared) signal transmitted from the optical beacon, perform photoelectric conversion, and multiplex / demultiplex the converted optical beacon signal. 17 is output. Further, the light emitting and receiving unit 15 and the photoelectric conversion unit 16 are configured to photoelectrically convert the optical beacon signal input from the multiplexing / demultiplexing unit 17 and transmit the converted optical (infrared) signal to the optical beacon. Have been.
[0023]
The multiplexing / demultiplexing unit 17 multiplexes the received radio wave beacon signal and optical beacon signal, for example, by a frequency division method, and transfers the multiplexed signal to the transmission / reception unit 13. Further, it receives the signal transferred from the transmission / reception unit 13 and separates the optical beacon signal. Note that a DC voltage for driving the antenna unit 12 is also multiplexed with these signals and supplied from the transmission / reception unit 13.
[0024]
On the other hand, the transmitting / receiving unit 13 includes a multiplexing / demultiplexing unit 18, a high-frequency converting unit 19, an intermediate frequency amplifying unit 20, a direct / directive detecting unit 21, a data reproducing / generating unit 22, an amplitude detecting unit 23, and a microcomputer (hereinafter referred to as CPU and 24), a memory such as a RAM 25, a communication control unit 26, a DC power supply 27, and the like.
[0025]
The multiplexing / demultiplexing unit 18 separates the radio beacon signal and the optical beacon signal multiplexed and transferred from the multiplexing / demultiplexing unit 17 of the antenna unit 12, and also generates the optical beacon signal generated by the data reproducing / generating unit 22. To the antenna unit 12.
[0026]
The high-frequency conversion unit 19 converts the radio wave beacon signal separated by the multiplexing / demultiplexing unit 18 into an intermediate frequency and outputs the intermediate frequency to the intermediate frequency amplifying unit 20. The intermediate frequency amplifier 20 demodulates the radio beacon signal of the intermediate frequency to generate radio beacon demodulated data, and outputs the radio beacon demodulated data to the direct / direction detecting unit 21. Further, the intermediate frequency amplifying unit 20 as a radio wave reception level detecting unit detects the intensity of the radio wave beacon signal and outputs it to the CPU 24 as a reception level. The direct / direction detecting unit 21 as a direct detection means detects a direct position of the radio beacon based on a direct detection signal superimposed on the radio beacon demodulated data and generates a direct signal. Further, the direct / direction detecting unit 21 generates radio beacon data from the radio beacon demodulated data, and outputs the generated radio beacon data and the direct signal to the CPU 24. Note that the intermediate frequency amplifying unit 20 and the direct / direction detecting unit 21 correspond to a radio wave beacon data detecting unit according to the present invention.
[0027]
The data reproducing / generating unit 22 as optical beacon data detecting means reproduces optical beacon data based on the optical beacon signal separated by the multiplexing / demultiplexing unit 18 and outputs the data to the CPU 24. The data reproducing / generating unit 22 generates an optical beacon signal from the optical beacon data output from the CPU 24 and outputs the optical beacon signal to the multiplexing / demultiplexing unit 18. The amplitude detection unit 23 as an optical reception level detection unit detects the intensity of the optical beacon signal input from the multiplexing / demultiplexing unit 18 and outputs it to the CPU 24 as a reception level.
[0028]
The CPU 24 constitutes a data processing means together with the intermediate frequency amplifying section 20, the direct / direction detecting section 21, the data reproducing / generating section 22, and the RAM 25. The CPU 24 performs radio wave beacon data processing and optical beacon data processing, which will be described later, according to a program stored in a non-volatile memory (not shown), and stores position information and road traffic information included in the radio beacon signal and the optical beacon signal. Is obtained and stored in the RAM 25. The CPU 24 transfers the information to an external device such as a car navigation system (not shown) via the communication control unit 26.
[0029]
The transmission / reception unit 13 includes an FM tuner, an FM detection unit, and an FM multiplex reproduction unit (not shown) for receiving FM multiplex broadcasting. Further, the DC power supply 27 receives a voltage supplied from a vehicle-mounted battery via an Acc switch of an ignition key cylinder, and generates a DC voltage to be supplied to each part of the antenna unit 12 and the transmission / reception unit 13.
[0030]
Next, the radio wave beacon data processing and the optical beacon data processing executed by the CPU 24 will be described separately with reference to FIGS. 2 to 5 as a main processing and a reception interruption processing.
[0031]
(1) Main processing
FIG. 2 shows a flowchart relating to main processing of radio wave beacon data and optical beacon data. FIG. 5 shows the intensity distribution of a radio beacon signal and an optical beacon signal on a general road, for example, at a place where an elevated road on which a radio beacon is installed and a general road on which an optical beacon intersects. The processing shown in FIG. 2 is used to explain processing characteristic of the present invention. The vertical axis of FIG. 5 represents the reception level of the optical beacon signal and the radio wave beacon signal, and the horizontal axis represents the position of the vehicle. The dashed line indicates the reference level used to determine whether the vehicle is located inside the communication area or outside the communication area.
[0032]
The CPU 24 compares the reception level of the radio wave beacon signal input from the intermediate frequency amplifier 20 with the preset reference level, and when the reception level of the radio beacon signal is equal to or higher than the reference level, the vehicle Is determined to be located within the communication area (the communication area is detected). In addition, the CPU 24 performs a similar process on the optical beacon based on the reception level of the optical beacon signal input from the amplitude detector 23 and the reference level to detect a communication area. In this case, the reference levels used for the radio beacon signal and the optical beacon signal may be different from each other.
[0033]
When the communication area is detected by such processing, the road-to-vehicle communication in-vehicle device 11 of the vehicle traveling on the general road from left to right in FIG. Then, the communication area of the optical beacon installed on the general road at point B is detected. Thereafter, the vehicle departs from the optical beacon communication area at point C and departs from the radio beacon communication area at point E. During this time, the road-vehicle communication in-vehicle device 11 detects a signal immediately below at point D due to a leak radio wave of the radio beacon. In such a case, in the conventional road-to-vehicle communication device, processing of the optical beacon data was not performed because the processing for the radio beacon that detected the communication area earlier was performed with priority, but the road-to-vehicle communication according to the present invention was not performed. The device 11 can process the optical beacon data according to the process described below.
[0034]
That is, in FIG. 2, the CPU 24 first determines whether or not the processing state is the "idle state" (step S1). As the processing state, “radio wave data processing state” in which radio wave beacon data is input by the interruption processing from the direct / direction detection unit 21 and the data processing is executed, and optical beacon data by the interruption processing from the data reproduction / generation unit 22 are executed. There are three states: an "optical data processing state" in which data processing is performed by inputting the data, and an "idle state" in which data processing is not performed on both beacon data. Here, since no data processing has been executed yet, it is determined in step S1 that the state is "idle state", and the process proceeds to step S2.
[0035]
In step S2, as described above, the reception level of the radio beacon signal and the optical beacon signal is compared with the reference level, and it is determined whether the communication area of the radio beacon or the communication area of the optical beacon has been detected (detected). If the area does not enter any area, the main processing ends. Further, when any communication area is detected, it is further determined in step S3 which communication area of the radio wave beacon or the optical beacon has been detected. If the communication area of the optical beacon is detected, the processing state is changed to "optical data processing state" (step S4), and if the communication area of the radio beacon is detected, the processing state is changed to "radio data processing state". (Step S5). In the example shown in FIG. 5, when the vehicle passes the position indicated by point A, the communication area of the radio wave beacon is detected, and the processing state is changed to the “radio wave data processing state”. After changing the processing state, the main processing ends.
[0036]
The main processing shown in FIG. 2 is repeatedly executed at regular intervals after the processing is completed, for example. In addition, due to the limitation due to the processing capacity, the CPU 24 performs an interrupt process for inputting the radio wave beacon data from the direct / direction detecting unit 21 (hereinafter, referred to as a reception interrupt process) and an optical beacon data from the data reproducing / generating unit 22. The configuration is such that input reception interrupt processing cannot be executed at the same time.
[0037]
If it is determined in step S1 that the state is not the "idle state", it is further determined in step S6 whether the processing state is the "radio wave data processing state" or the "optical data processing state". In the case of the “optical data processing state”, the reception interruption of the optical beacon data is permitted. Then, a data frame (hereinafter, referred to as a frame) is generated on the RAM 25 based on the optical beacon data input one byte at a time from the data reproduction / generation unit 22 by the reception interruption process (step S7). This frame represents information transmitted from an optical beacon, such as position information and road traffic information. The reception interruption process is the same as the reception interruption process for the radio wave beacon data described later (see FIG. 3), and the description is omitted here.
[0038]
Subsequently, in step S8, it is determined whether the optical beacon is out of the communication area. If it is within the communication area, the process returns to the step S7. If it is outside the communication area, the reception interruption of the optical beacon data is prohibited in step S9, and the input of the optical beacon data is stopped.
[0039]
After that, in step S10, the frames of the optical beacon generated on the RAM 25 are grouped for each ID and converted into a format that can be transferred to an external device such as a navigation system. Then, in step S11, the processing state is changed from the "optical data processing state" to the "idle state", and the main processing ends. The transfer to the external device is performed according to a transfer processing routine (not shown).
[0040]
On the other hand, when it is determined in step S6 that the radio wave data is being processed, reception interruption of radio wave beacon data is permitted. Then, a frame is generated in the RAM 25 based on the radio wave beacon data input one byte at a time from the direct / direction detecting unit 21 by the reception interruption process (step S12). This frame represents information transmitted from a radio beacon, such as position information and road traffic information.
[0041]
After that, in step S13, the level of the signal directly below from the direct / direction detecting unit 21 is inspected, and it is determined whether the signal directly below the radio beacon is detected. Since the level immediately below the point immediately below the point (for example, L level) and the level after passing through the point immediately below (for example, H level) are different levels, the point where the level change occurs is determined. It is directly below the radio beacon. Since the flag is set once after the detection of immediately below, the determination in step S13 continues to be “YES” until the flag is cleared in step S15.
[0042]
Further, when the position immediately below is detected, it is determined in step S14 whether or not the communication area of the radio beacon has been removed. If it is located in the communication area, the process returns to step S12. If it is out of the communication area, the reception interruption of the radio wave beacon data is prohibited, and the input of the radio wave beacon data is stopped (step S15). After that, similarly to the frame processing of the optical beacon data, the frame format of the radio wave beacon is converted in step S10, the processing state is changed from the “radio wave data processing state” to the “idle state” in step S11, and the main processing is performed. finish.
[0043]
In addition to the above processing, the following characteristic processing is added in the road-vehicle communication in-vehicle device 11 of the present invention. That is, when the position immediately below the radio beacon is not detected in step S13 (when the vehicle is located between the points A and D in the example shown in FIG. 5), the reception interruption of the radio beacon is prohibited in step S16. At the same time, the reception interruption of the optical beacon data is permitted, and the trial receiving process of inputting the optical beacon data is executed. This trial reception processing is the same processing as the processing in step S7.
[0044]
Subsequently, it is determined whether an optical beacon frame is detected in step S17. If it is detected, the reception processing of the radio wave beacon data is interrupted (step S18), the processing state is changed to the "optical data processing state" (step S19), and the main processing ends. In FIG. 5, when the vehicle passes point B and enters the communication area of the optical beacon, the processing state is changed to the “optical data processing state”. After that, until the vehicle passes through the point C which exits the communication area of the optical beacon, the CPU 24 is not installed on the general road on which the vehicle is traveling, but not on the radio beacon signal due to the radio wave leakage from the radio beacon. Data processing can be performed on the optical beacon signal from the optical beacon.
[0045]
As described above, the road-to-vehicle communication in-vehicle device 11 determines that the communication area of the radio beacon has been detected when the reception level of the radio beacon signal is equal to or higher than the reference level, and generates the frame by inputting the radio beacon data. I do. Similar processing is performed for the optical beacon. Further, even during the processing of the radio wave beacon data (“radio wave data processing state”), for example, the road-vehicle communication in-vehicle device 11 can periodically input the optical beacon data, and the optical beacon frame is detected. In such a case, the processing is switched to the processing for the optical beacon data (“optical data processing state”).
[0046]
Therefore, as shown in FIG. 5, when the optical beacon installed on the road on which the vehicle is traveling and the radio beacon installed on another road are close to each other, the communication area of the optical beacon signal and the radio beacon Even if the communication area overlaps with the communication area due to radio waves leaked from the vehicle, information transmitted from the optical beacon can be preferentially obtained, and information loss to the driver can be prevented.
[0047]
Further, in the present embodiment, when a position directly below the radio beacon is detected during the processing of the radio beacon data, the trial reception processing of the optical beacon data is stopped, and only the processing of the radio beacon data is executed. Therefore, the CPU 24 only needs to execute the processing of the radio wave beacon data from the time immediately below the detection until the radio wave beacon is out of the communication area. A sufficient processing time for performing the above. Further, the CPU 24 does not adopt the frame of the generated radio wave beacon data when it cannot normally detect a signal directly below such as a radio wave from a radio beacon, so that it is easy to eliminate erroneous information due to the leak radio wave. It works.
[0048]
(2) Receive interrupt processing
FIG. 3 shows a flowchart relating to the reception interruption processing of the radio wave beacon data. This flowchart can be applied to the optical beacon data reception interrupt processing as it is. This reception interruption process is in the main process shown in FIG. 1, during which the reception interruption is permitted for the radio wave beacon data from step S12 to step S14, and the direct / direction detection unit 21 performs Occurs when radio beacon data is newly detected.
[0049]
The CPU 24 inputs 1-byte radio beacon data in step T1. Then, in step T2, for the frame from the radio wave beacon currently being received, it is determined whether the input of all the data constituting the frame has been completed. The frame of the radio beacon is composed of a synchronization part, a header part, a data part, and a CRC (Cyclic Redundancy Check) each having a predetermined number of bytes. If the input of all data has not been completed, the reception interrupt processing ends. On the other hand, when the input is completed, the CRC of the frame is checked (step T3). If the inspection result is correct, in step T4, a frame inspection process for inspecting whether the generated frame is a frame of a radio beacon to be processed is executed. This frame inspection processing will be described later. If there is an error in the inspection result, the reception interrupt processing ends.
[0050]
When the frame inspection process is executed, “OK” is returned if the generated frame is for the radio beacon to be processed, and “NG” is returned if the generated frame is not for the radio beacon to be processed. . The return value is checked in step T5, and if "OK", the frame is stored in the RAM 25 (step T6), and if "NG", the reception interrupt processing ends.
[0051]
FIG. 4 shows a flowchart relating to the frame inspection processing. Hereinafter, the frame inspection process will be described with reference to FIG.
First, in step T41, the beacon number extracted from the frame is checked. The beacon numbers are different identification numbers given to beacons installed nationwide. Specifically, if the first digit of the beacon number is 1 to 9, the process proceeds to the next step T42 as an appropriate beacon number, and otherwise, the process proceeds to step T48 on the assumption that there is an error in the beacon number. In step T48, the CPU 24 performs initialization (hereinafter, referred to as reception initialization) of input frames and the like as preparation for inputting new radio beacon data from the direct-direction / direction detection unit 21.
[0052]
In step T42, it is determined whether the beacon number is the same as the number of the radio beacon interrupted in step S18 due to the occurrence of the optical beacon data processing or the number of the radio beacon interrupted in step T47 described later. In the same case, since the frame of the radio wave beacon has already been stored in the RAM 25 before the interruption, the process shifts to step T48 to perform reception initialization.
[0053]
In step T43, it is determined whether or not the frame is for a beacon to be processed based on the beacon number. The beacon to be processed is set in step T45, which will be described later, every time the radio wave beacon to be received is changed, and represents a radio beacon in which frame processing is in progress. When the reception is initialized in step T48, the number of the beacon to be processed is initialized to an appropriate number that does not exist as a radio beacon (for example, the first digit is 0). If the frame being processed is that of the beacon to be processed, that is, if the frame processed as the previous processing and the frame are transmitted from the same radio beacon, the process proceeds to step T46. After setting a return value of “OK”, the frame inspection processing ends.
[0054]
On the other hand, if the frame is not a beacon to be processed, that is, if the previously processed frame and the current processed frame are transmitted from different radio beacons, or if it is the first frame generated after reception initialization Then, the process proceeds to step T44.
[0055]
Step T44 is a process of determining whether or not a beacon to be processed has been set, and “NO” is determined only when the process is first performed after the reception is initialized in step T48. If the determination is "NO", the radio wave beacon of the frame is newly set as a beacon to be processed (step T45), and the process shifts to step T46 to return "OK" as a return value.
[0056]
If “YES” is determined in step T44, that is, if the received radio beacon is changed, the reception of the radio beacon which has been processed so far is interrupted (step T47), and a new radio beacon is transmitted. The reception initialization for input is performed (step T48). After that, the process shifts to step T49 to return "NG" as a return value.
[0057]
Now, the above processing will be described with reference to the case shown in FIG. Here, information composed of frames a1 and a2 is repeatedly transmitted from the radio beacon 1a shown in FIG. 8B, and information composed of frames b1, b2 and b3 is repeatedly transmitted from the radio beacon 1b. It is assumed that It is assumed that the vehicle is traveling from left to right in the figure.
[0058]
At the point A, when the vehicle enters the communication area and the road-vehicle communication in-vehicle device 11 receives the frame a1 from the radio wave beacon 1a, steps T41 to T46 are sequentially processed. In this case, in step T45, the radio wave beacon 1a is set as a beacon to be processed. Subsequently, when the frame a2 is received, since the frame is a frame transmitted from the beacon to be processed (the radio wave beacon 1a), “YES” is determined in the step T43, and a return value of “OK” is returned as the beacon to be processed. . Thereby, the road-vehicle communication in-vehicle device 11 can acquire the information from the radio wave beacon 1a including the frames a1 and a2 on the RAM 25.
[0059]
Thereafter, when the vehicle enters a communication area capable of receiving the radio wave from the radio beacon 1b at the point B while maintaining the reception level of the radio beacon at or above the reference level, the processing state shifts to the "idle state". Without this, a frame transmitted from the radio beacon 1b is received.
[0060]
Now, when the frame b1 is received following the frame a2, in step T43, it is determined that the frame is not the frame of the processing target beacon (the radio wave beacon 1a), and the process proceeds to step T44. In step T44, since the radio wave beacon 1a has already been set as the processing target beacon in step T45, it is determined to be "YES", and the reception process is interrupted and the reception initialization is executed. At this time, the beacon to be processed is initialized to, for example, a radio beacon 0 (a non-existent radio beacon having a number whose first digit is 0).
[0061]
Subsequently, when the frame b2 is received, after processing in steps T41 to T44, the radio wave beacon 1b is set as a beacon to be processed in step T45, and the frame b2 is stored in the RAM 25. Thereafter, as long as the frames b3, b1, b2,... Of the radio wave beacon 1b are received, the determination of "YES" is continued in step T43, and each frame is stored in the RAM 25. Thus, the road-vehicle communication in-vehicle device 11 can acquire information from the radio wave beacon 1b including the frames b1, b2, and b3.
[0062]
As described above, the in-vehicle road-vehicle communication device 11 is configured to be able to identify the radio beacon that transmitted the frame based on the generated frame in the reception interrupt processing of the radio beacon data. Then, when the identified radio beacon is not the target beacon, that is, when the radio beacon to be received is changed due to the movement of the vehicle, a frame transmitted from the radio beacon that has newly received radio waves is acquired. It has become.
[0063]
Therefore, as shown in FIG. 8B, even when a plurality of radio beacon signals overlap to form one communication area, information transmitted from each radio beacon is reliably obtained. can do. The above-described reception interrupt processing is similarly applied to optical beacon data.
[0064]
(Second embodiment)
Next, a second embodiment in which the transmission / reception unit 13 in the first embodiment is modified will be described with reference to FIGS. 6, the same components as those in FIG. 1 are denoted by the same reference numerals, and only different components will be described here.
[0065]
FIG. 6 schematically shows the electrical configuration of the road-vehicle communication in-vehicle device using functional blocks. In FIG. 6, the road-vehicle communication in-vehicle device 28 includes the antenna unit 12 and the transmission / reception unit 29.
The transmission / reception unit 29 includes a multiplexing / demultiplexing unit 18, a high-frequency conversion unit 30, an amplitude detection unit 23, a decoder 31, a microcomputer (hereinafter, referred to as a CPU) 32, a RAM 25, a communication control unit 26, a DC power supply 27, and the like. I have.
[0066]
The high frequency converter 30 converts the radio beacon signal separated by the multiplexing / demultiplexing unit 18 into an intermediate frequency, and demodulates the radio beacon signal to generate radio beacon demodulated data. Further, the high-frequency converter 30 as a radio wave reception level detecting unit detects the intensity (reception level) of the radio wave beacon signal. The radio wave beacon demodulated data is output to the decoder 31, and the reception level is output to the CPU 32.
[0067]
The decoder 31 as beacon information generating means receives the radio wave beacon demodulated data and the optical beacon signal separated by the multiplexing / demultiplexing unit 18 and can simultaneously generate a radio beacon frame and an optical beacon frame. It is configured as follows. In addition, the decoder 31 as a direct detection means detects a direct signal indicating a direct position of the radio beacon based on a direct detection signal superimposed on the radio beacon demodulated data. When the decoder 31 generates either a radio wave beacon or an optical beacon frame, the decoder 31 outputs a reception notification interrupt signal to the CPU 32 and outputs the frame to the CPU 32.
[0068]
The CPU 32, which constitutes a data processing means together with the high-frequency converter 30, the decoder 31, and the RAM 25, inputs a frame (information) to be described later according to a program stored in advance in a nonvolatile memory (not shown). It is stored in the RAM 25. Further, the CPU 32 outputs an area signal indicating the inside and outside of the communication area of the radio wave beacon to the decoder 31. The decoder 31 outputs a direct signal to the CPU 32 only when this area signal indicates the inside of the communication area.
[0069]
Next, the operation and effect of the present embodiment will be described with reference to FIG. 7 which shows a flowchart relating to main processing of radio wave and optical beacon data. In FIG. 7, the same processes as those in the flowchart shown in FIG. 2 are denoted by the same step numbers, and different processes will be described below.
[0070]
When the communication area of the radio beacon or the optical beacon is detected in step S2, the processing state is changed from "idle state" to "beacon reception state" in step S20. In the present embodiment, there are two processing states, an “idle state” and a “beacon reception state” in which either a radio beacon or an optical beacon is input from the decoder 31. This frame includes information transmitted from a radio wave or an optical beacon.
[0071]
If it is determined in step S1 that the frame is not in the "idle state", the CPU 32 receives the reception notification interrupt signal from the decoder 31, and determines whether the frame input from the decoder 31 is a radio beacon frame or an optical beacon frame (step S1). S21). If the frame is an optical beacon frame, the frame transfer of the radio beacon is interrupted (step S22), and the frame is transmitted by inputting the frame of the optical beacon and storing it in the RAM 25 (step S23).
[0072]
After that, in step S8, it is determined whether the optical beacon is out of the communication area. When it is within the communication area, the process returns to step S21, and when it is outside the communication area, the process proceeds to step S10.
[0073]
On the other hand, if it is determined in step S21 that the input frame is a radio beacon frame, the radio beacon frame is transferred from the decoder 31 to the RAM 25 via the CPU 32 (step S24). Subsequently, in step S14, it is determined whether the vehicle has left the communication area of the radio wave beacon. Then, if it is located within the communication area, it is determined whether or not a position immediately below the radio wave beacon has been detected (step S13). If it has left the communication area, the frame transfer is terminated and the processing state is changed to "beacon reception state". To return to the "idle state" (step S11).
[0074]
If it is determined that the radio wave beacon signal has just been received, the frame stored in the RAM 25 is regarded as valid. Then, in step S10, the frame is converted into a format that can be transferred to an external device. If the position immediately below is not detected, the process returns to step S21.
[0075]
As described above, in the roadside-vehicle communication in-vehicle device 28, the decoder 31 is configured to be able to simultaneously generate a radio beacon frame and an optical beacon frame, and the CPU 32 selects and inputs the frame generated by the decoder 31. Then, a frame transfer process to be stored in the RAM 25 is executed. When both the optical beacon frame and the radio beacon frame are generated, the optical beacon frame is preferentially selected. Therefore, as in the first embodiment, the optical beacon frame is selected. Even when the communication area of the signal and the communication area of the radio wave beacon leaked from the radio wave beacon overlap, it is possible to obtain information transmitted from the optical beacon, thereby preventing the driver from missing information. .
[0076]
Further, the decoder 31 can independently generate frames for the radio wave beacon and the optical beacon, and the CPU 32 only has to select the frame generated by the decoder 31 and transfer it to the RAM 25. And the processing speed can be increased.
[0077]
(Other embodiments)
Note that the present invention is not limited to the above embodiments, and the following modifications or extensions are possible.
In the second embodiment, the frame generated by the decoder 31 is transferred to the RAM 25 via the CPU 32. However, the frame may be directly transferred from the decoder 31 to the RAM 25 by DMA (Direct Memory Access).
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing an electric configuration of a vehicle-mounted road-vehicle communication device according to a first embodiment of the present invention;
FIG. 2 is a flowchart showing main processing.
FIG. 3 is a flowchart showing reception interrupt processing;
FIG. 4 is a flowchart showing a frame inspection process;
FIG. 5 is a diagram showing reception levels of an optical beacon signal and a radio beacon signal;
FIG. 6 is a view corresponding to FIG. 1, showing a second embodiment of the present invention;
FIG. 7 is a diagram corresponding to FIG. 2;
FIG. 8 is a diagram showing a reception level of a radio wave from a radio beacon;
FIG. 9 is a diagram showing a state in which a radio beacon and an optical beacon are installed close to each other.
[Explanation of symbols]
In the drawings, 11 and 28 are road-vehicle communication in-vehicle devices, 13 is an antenna (reception unit), 14 is a high-frequency reception unit (reception unit), 15 is a light emission and reception unit (reception unit), and 16 is a photoelectric conversion unit (reception unit). , 20 is an intermediate frequency amplifier (data processing means, radio wave beacon data detection means, radio wave reception level detection means), 21 is a direct / direction detection section (data processing means, radio beacon data detection means, direct detection means), 22 is Data reproducing / generating unit (data processing unit, optical beacon data detecting unit), 23 is an amplitude detecting unit (optical receiving level detecting unit), 24 and 32 are microcomputers (data processing unit), 25 is RAM (data processing unit) , 30 are high-frequency conversion units (data processing means, radio wave reception level detection means), and 31 is a decoder (data processing means, beacon information generation means, direct detection means).

Claims (1)

Receiving means for receiving a radio wave beacon signal transmitted from a road station installed along the road,
Radio wave beacon data detection means for detecting radio beacon data from the radio beacon signal received by the reception means,
Radio wave reception level detection means for detecting the reception level of the radio wave beacon signal received by the receiving means,
When the reception level from the radio wave reception level detecting means is equal to or higher than a predetermined reference level, the radio station transmits the radio beacon signal based on the radio beacon data from the radio beacon data detecting means, and , and a data processing means for acquiring the information transmitted from the identified road on station based on the radio beacon data,
The data processing means, if the reception level from the radio wave reception level detection means is in a communication area capable of receiving radio waves from different road stations while maintaining a state of being equal to or higher than a preset reference level, Each time a different road station is identified, the information transmitted from each of the identified road stations is acquired based on the radio wave beacon data .

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