JP2001004730A - Bit error rate measuring method and its measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bit error rate measuring method and a measuring apparatus which can grasp the position of a vehicle with high precision and eliminate the moving limitation of the vehicle. SOLUTION: A BER(bit error rate) processing part 1 of this measuring apparatus takes in a carrier wave transmitted from an apparatus mounted on a vehicle, from an antenna 11, performs signal processing, and calculates BER. An azimuth processing part 2 performs detection processing of arrival azimuth of the carrier wave taken in an antenna 21 being in parallel with the antenna 11 in the BER processing part 1, and specifies the position of a vehicle, from the result of processing. A data processing part 3 makes the calculated value of BER correspond to position information of the vehicle, and forms accurate BER characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and apparatus for measuring a bit error rate, and more particularly to a method and apparatus for measuring a bit error rate in a road-to-vehicle communication system using wireless communication.

[0002]

2. Description of the Related Art Road-to-vehicle communication system (DSRC: Dedica)
The ted Short Range Communication) is used in a non-stop automatic toll collection system (ETC: Electronic Toll Collection System) which is one application example of an intelligent transport system (ITS).

[0003] This road-vehicle communication system has a roadside device between a wireless device installed on the roadside (hereinafter referred to as a roadside device) and a wireless device mounted on a vehicle (hereinafter referred to as an onboard device). This is a system that performs wireless communication within a communication range. FIG. 3 is a bird's-eye view showing an outline in one direction of a road showing an example of a device installation state of the present invention. As shown in FIG. 3, the vehicle-mounted device 2 mounted on a vehicle 201 traveling on a road 200
02 and the pillar 20 on the road located in the traveling direction of the vehicle 201
4 has a function of performing wireless communication with the roadside device 203 installed in the device 4.

Further, in this system, it is necessary that the roadside device and the in-vehicle device moving at high speed can reliably perform data communication within the communication range set for each.

That is, in this road-vehicle communication system,
It is necessary to ensure that the roadside device and the vehicle-mounted device installed in various environments can reliably communicate within a predetermined communication range. As one of the methods, a bit error rate (BE) indicating the degree of error in data transmission / reception is shown.
R: Bit Error Rate) is effective.

In this system, there are two types of communication directions, namely, a downlink for communicating from the roadside device to the vehicle-mounted device and an uplink for communicating from the vehicle-mounted device to the roadside device. In any case, it is necessary to specify the position of the vehicle in order to accurately measure the BER, but conventionally, a movement detection unit mounted on the vehicle has been used. Hereinafter, as a conventional example,
A BER measurement method in the case of a downlink in which an in-vehicle device including a movement detection unit is a receiving side will be described.

FIG. 4 is a block diagram showing an example of a conventional bit error rate measuring device. Referring to FIG.
The conventional BER measuring device can be roughly classified into three processes: a BER processing unit 1 for performing BER measurement, a position processing unit 4 mounted on a vehicle to measure a position, and a data processing unit 3 for processing measurement information. And a vehicle-mounted device mounted on a vehicle.

The BER processing unit 1 includes an antenna 11 for receiving a carrier wave transmitted from a roadside device, a receiving unit 12 for down-converting a received signal to a predetermined frequency, and a level for outputting a detection signal corresponding to the received signal level. Detector 13
And a comparison unit 1 for generating a reception digital signal from the detection signal
4, a data reproducing unit 15 for generating a reception clock and reception data from a reception digital signal, and a BER calculation unit 16 for comparing a reception data sequence with a transmitted data sequence to calculate a BER.

The position processing unit 4 includes a movement detecting unit 41 and a position calculating unit 42. An example of the movement detection unit 41 is a sensor installed on a tire portion of a vehicle equipped with an on-vehicle device. This sensor generates a pulse each time the tire makes one rotation, that is, every time the tire advances a certain distance. Each time the onboard unit travels a certain distance, the movement detection unit 41
Are output to the position calculation unit 42,
Here, the initial value input first and the number of pulses output from the movement detection unit 41 are calculated, and the movement distance up to the present is calculated and output to the data processing unit 3.

The data processing unit 3 inputs the BER calculation value from the BER calculation unit 16 and the movement distance calculation value from the position calculation unit 42 and records them in association with each other. In the same manner, in accordance with the movement of the vehicle-mounted device, the BER measurement value and the movement position information are recorded in association with each movement, and the recording result is output.

[0011]

SUMMARY OF THE INVENTION The above-mentioned conventional BER
In the downlink, in which the on-board unit including the movement detection unit 41 is used as the reception side, the movement detection unit 41, which is a means for specifying a position important for BER measurement, can obtain the accuracy required for the measurement. Has the disadvantage of not being. The reason for this is that since the sensor of the movement detection unit 41 is attached to the tire of the vehicle, an error occurs due to the expansion and contraction of the tire, and the lateral movement cannot be grasped. Since the communication range defined in the road-vehicle communication system is very narrow and the interval between adjacent communication ranges is close, high-precision measurement is required, and this requirement has not been satisfied conventionally.

On the other hand, there is a problem in the convenience of the BER measurement in the uplink where the roadside device is on the receiving side. Contrary to the downlink case, it is necessary to specify the position of the on-board unit on the receiving roadside unit, and for this purpose, the pulse signal from the onboard unit mounted on the moving vehicle is processed by the data processing unit To be connected to the vehicle, and the degree of freedom of movement of the vehicle-mounted device is impaired.

An object of the present invention is to provide a BE in a road-to-vehicle communication system capable of acquiring a position of a vehicle-mounted device with high accuracy using a direction finder and obtaining a high-accuracy BER measurement result.
An object of the present invention is to provide an R measuring method and a measuring device therefor.

It is another object of the present invention to provide a BER measuring method and a measuring apparatus capable of eliminating the restriction on the movement of the vehicle-mounted device by specifying the position of the vehicle only on the roadside device side.

[0015]

A bit error rate measuring apparatus according to the present invention is a vehicle-to-vehicle communication system for communicating between a roadside device installed on a roadside and a vehicle-mounted device mounted on a vehicle. Receiving the carrier wave transmitted from the roadside device and transmitting a bit error rate (BER: BitError Rat)
e), the direction of arrival of the carrier wave is detected, the position of the vehicle equipped with the on-vehicle device is specified, and the BE
The method is characterized in that a BER characteristic is created by associating the measured value of R with the specified position information of the vehicle.

In a bit error rate measuring device provided in the roadside device in a roadside-vehicle communication system for performing communication between a roadside device installed on the roadside and a vehicle-mounted device mounted on a vehicle, A BER processing unit that receives a transmitted carrier wave and measures BER; an azimuth processing unit that detects an arrival direction of the carrier wave and identifies a position of the vehicle equipped with the on-vehicle device; And a data processing unit that creates a BER characteristic by associating the measured value of the BER with the position information of the vehicle specified by the azimuth processing unit.

Also, the BER processing unit includes a first antenna for receiving a carrier transmitted from the on-vehicle device, a receiving unit for down-converting a signal received from the first antenna to a predetermined frequency, A level detection unit that outputs a detection signal corresponding to the reception signal level that has been frequency-downconverted from a reception unit, and a comparison unit that compares the detection signal with a reference voltage set internally to generate a reception digital signal. A data reproducing unit that receives the received digital signal and generates a reception clock and reception data, and a BER calculation unit that calculates the BER by comparing the generated reception data sequence with the transmitted original data sequence. It is characterized by being composed.

Further, the azimuth processing unit includes a second antenna for receiving a carrier transmitted from the on-vehicle device, an azimuth detecting unit for detecting an arrival azimuth of the carrier received by the second antenna, And a azimuth position calculator for calculating the position of the vehicle from the azimuth information obtained by the azimuth detector and outputting the position information.

Further, the azimuth processing unit includes N (N is an integer of 3 or more) second antennas for receiving the carrier wave transmitted from the vehicle-mounted device, and N number of second antennas. N frequency converters for down-converting the received carrier to a predetermined frequency, and a phase difference between a phase of a received signal output from each of the N frequency converters and an internally set reference phase N phase detectors, N A / D converters for converting the phase detection signals extracted from each of the N phase detectors into digital signals, and the N A / D converters And a azimuth position calculator for calculating azimuth information based on the N digital signals extracted from each of the converters and outputting position information of the vehicle.

Further, the N second antennas are provided adjacent to the first antenna of the BER processing unit and arranged at a predetermined distance from each other.

[0021]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of a BER measuring apparatus according to the present invention, and FIG.
FIG. 3 is a detailed block diagram illustrating an example of an orientation processing unit illustrated in FIG.

In the present embodiment shown in FIG. 1, in the road-to-vehicle communication system, the on-vehicle device 202 shown in FIG.
A BER processing unit 1 for measuring the BER, the BER processing unit 1 comprising:
An azimuth processing unit 2 for specifying an azimuth and a position, and a data processing unit 3 for creating a BER characteristic from the measured value of the BER and the azimuth position information.

In FIG. 1, components corresponding to those shown in FIG. 4 are denoted by the same reference numerals or symbols.

The BER processing unit 1 includes an antenna 11 for receiving a carrier wave transmitted from the vehicle-mounted device, a receiving unit 12 for down-converting a received signal to a predetermined frequency, and a level for outputting a detection signal corresponding to the received signal level. Detector 13
A comparison unit 14 for comparing the detection signal with an internally set reference voltage to generate a reception digital signal; a data reproduction unit 15 for generating a reception clock and reception data from the reception digital signal; And a BER calculating unit 16 that calculates a BER by comparing the calculated data string.

The azimuth processing unit 2 includes an antenna 21 for receiving a carrier wave transmitted from the on-vehicle device, an azimuth detecting unit 22 for detecting an arrival direction of the received carrier wave, and a position of the vehicle calculated from the azimuth information. Azimuth position calculator 2 that outputs information
3

FIG. 2 is a detailed block diagram showing an example of the azimuth processing unit 2. The azimuth processing unit 2 shown in FIG. 1 is an example of three antennas, and three antennas 111, 121, and 131 arranged at a certain interval, and are provided corresponding to each antenna and down-converted to a predetermined frequency. Frequency converters 112, 122, 132, phase detectors 113, 123, 133 for detecting a phase difference between the phase of the received signal and an internally set reference phase, and an A / A for converting the phase detected signal into a digital signal. D conversion units 114, 124, 1
34, and an azimuth position calculator 141 for calculating azimuth information based on three digital signals and outputting vehicle position information. The antennas 111, 121, and 131 correspond to the antenna 21 in FIG. 1, and the azimuth position calculator 141 corresponds to the azimuth position calculator 23 in FIG.

The data processing unit 3 creates a BER characteristic by associating the measured BER value from the BER processing unit 1 with the position information of the vehicle from the azimuth processing unit 2.

Next, the operation of the present embodiment will be described in more detail with reference to FIGS. In the road-vehicle communication system, the carrier wave transmitted from the vehicle-mounted device is received by the antennas 11 and 21 in FIG. 1, respectively.

The antenna 11 receives and outputs a carrier wave transmitted from a vehicle-mounted device mounted on the vehicle.

The receiving section 12 amplifies the carrier output from the antenna 11 and mixes it with a local oscillation frequency from a local oscillator (not shown) to downconvert the carrier to a predetermined frequency.

The level detector 13 outputs a detection signal corresponding to the signal level of the received carrier from the receiver 12.

The comparison section 14 compares the detection signal output from the level detection section 13 with a reference voltage set internally to generate a reception digital signal.

The data reproducing section 15 generates a reception clock and reception data from the reception digital signal output from the comparison section 14.

Further, the BER calculating section 16 compares the received data string output from the data reproducing section 15 with the transmitted data string, calculates the BER, and outputs the BER to the data processing section 3.

On the other hand, the antenna 21 shown in FIG. 1, that is, the antennas 111, 112, and 113 shown in FIG. 2, respectively receive and output the carrier wave transmitted from the vehicle-mounted device.

The frequency conversion units 112, 122, 123
The carrier wave received by each of the antennas 111, 112, and 113 is amplified and mixed with a local oscillation frequency from a common local oscillator (not shown) to down-convert to a predetermined frequency.

The phase detectors 113, 123 and 133 detect the phase difference between the phase of the received signal output from each of the frequency converters 112, 122 and 123 and the internally set reference phase. A corresponding phase detection signal is output.

The A / D converters 114, 124, and 134 convert the phase detection signals output from each of the phase detectors 113, 123, and 133 into digital signals.

The azimuth position calculation unit 141 (corresponding to the azimuth position calculation unit 23 in FIG. 1) has A / D conversion units 114 and 12.
The azimuth information is calculated by a known method based on the three digital signals output from each of 4,134, and the position information of the vehicle is output.

Finally, the data processing unit 3 in FIG.
BER calculation value from calculation unit 16 and azimuth position calculation unit 2
The BER characteristic is created by associating and recording the azimuth position information from 3 (141).

Here, the BER measuring device of the present invention is provided in a roadside device, and transmits a carrier transmitted from a vehicle mounted on a vehicle moving within the communication range of the roadside device to three antennas 111, 121 and 131, and the position of the vehicle can be specified with high accuracy by calculating the position information of the vehicle from the three direction information.

Note that the present invention is not limited to the above embodiment. For example, the number of antennas connected by the azimuth processing unit 2 may be four or more. The vehicle position can be specified with higher accuracy.

In this embodiment, since the position of the vehicle (vehicle-mounted device) can be specified only by the roadside device, it is not necessary to connect to the vehicle-mounted device for position detection.

[0044]

As described above, the present bit error rate measuring device can accurately detect the azimuth of the carrier wave transmitted from the on-vehicle device by using the azimuth detecting unit provided on the roadside device side. This has the effect of creating an excellent BER characteristic.

Further, since the position of the vehicle can be specified only by the roadside device, the connection for detecting the position with the vehicle-mounted device is not required, and the convenience is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a BER measuring device according to the present invention.

FIG. 2 is a detailed block diagram showing an example of an azimuth processing unit 2 shown in FIG.

FIG. 3 is a bird's-eye view showing an outline in one direction of a road showing an example of a device installation state of the present invention.

FIG. 4 is a block diagram showing a conventional BER measuring device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 BER processing unit 2 azimuth processing unit 3 data processing unit 4 position processing unit 11, 21 antenna 12 reception unit 13 level detection unit 14 comparison unit 15 data reproduction unit 16 BER calculation unit 22 azimuth detection unit 23, 141 azimuth position calculation unit 41 Movement detection unit 42 Position calculation unit 111, 121, 131 Antenna 112, 122, 132 Frequency conversion unit 113, 123, 133 Phase detection unit 114, 124, 134 A / D conversion unit 200 Road 201 Vehicle 202 In-vehicle device 203 Roadside device 204 Prop

Claims (6)

[Claims] A roadside-vehicle communication system for performing communication between a roadside device installed on a roadside and a vehicle-mounted device mounted on a vehicle, wherein a carrier wave transmitted from the vehicle-mounted device is received by the roadside device and a bit is transmitted. Error rate (BER: Bit Error Rat)
e), the direction of arrival of the carrier wave is detected, the position of the vehicle equipped with the on-vehicle device is specified, and the BE
A bit error rate measurement method, wherein a BER characteristic is created by associating the measured value of R with the specified position information of the vehicle. 2. A bit error rate measuring device provided in a roadside device in a roadside-vehicle communication system for performing communication between a roadside device installed on a roadside and a vehicle-mounted device mounted on a vehicle, wherein: A BER processing unit that receives a transmitted carrier wave and measures BER; an azimuth processing unit that detects an arrival direction of the carrier wave and identifies a position of the vehicle equipped with the on-vehicle device; And a data processing unit for creating a BER characteristic by associating the measured value of the BER from the vehicle with the position information of the vehicle specified from the azimuth processing unit. 3. The first antenna for receiving a carrier wave transmitted from the on-vehicle device, the BER processing unit comprising:
A receiving unit that frequency downconverts a reception signal from the antenna to a predetermined frequency, a level detection unit that outputs a detection signal corresponding to the reception signal level that has been frequency downconverted from the reception unit, A comparison unit that compares the reference voltage set in Step 1 to generate a reception digital signal; a data reproduction unit that receives the reception digital signal and generates a reception clock and reception data; 3. The bit error rate measuring device according to claim 2, further comprising: a BER calculating unit that calculates a BER by comparing the calculated original data string. 4. The azimuth processing unit, a second antenna for receiving a carrier transmitted from the on-vehicle device, an azimuth detecting unit for detecting an arrival azimuth of the carrier received by the second antenna, 4. The bit error rate measurement according to claim 2, further comprising an azimuth position calculation unit that calculates the position of the vehicle from the azimuth information obtained by the azimuth detection unit and outputs the position information. apparatus. 5. The azimuth processing unit includes N (N is an integer of 3 or more) second antennas for receiving a carrier transmitted from the on-vehicle device, and N number of second antennas. N frequency converters for down-converting the received carrier to a predetermined frequency, and a phase difference between a phase of a received signal output from each of the N frequency converters and an internally set reference phase And N A / D converters for converting the phase detection signals extracted from each of the N phase detectors into digital signals.
A directional position calculating unit that calculates directional information based on the N digital signals extracted from each of the N A / D converters and outputs position information of the vehicle. The bit error rate measuring device according to claim 2, 3, or 4, wherein 6. The N number of second antennas are connected to the BE.
6. The bit error rate measuring device according to claim 2, wherein the bit error rate measuring device is provided adjacent to the first antenna of the R processing unit and arranged at a predetermined distance from each other.