TWI464708B - Electrical toll collection system with terminal limiting communication zone - Google Patents

Description

Communication area limiting device for ETCS terminal

The invention is a communication area limiting device of an ETCS terminal, and the ETCS terminal of the invention can precisely adjust the receiving performance of the ETCS terminal to improve the communication success rate of the communication area of the ETCS terminal.

The Electric Toll Collection System (hereinafter referred to as "ETCS"), also known as the highpass system, is a non-stop charging system using the 5.8 GHz wireless communication system, which can slow down traffic jams, improve environmental pollution and traffic systems. A basic transportation unit (Intelligent Transport System, hereinafter referred to as "ITS") constitutes a basic unit.

The above ETCS communication system uses the Amplitude Shift Keying ("ASK") method of 5.8 GHz bandwidth, and there are two types of passive and active, and the active type can easily implement ETCS and ITS.

Figure 1 is a general structural diagram of an electronic toll collection system.

Referring to FIG. 1 , an Electronic Toll Collection System (ETCS) includes an On Board Unit (hereinafter referred to as “OBU” 110 , a first vehicle detector 120 , a second vehicle detector 125 , and a first Road Side Equipment (hereinafter referred to as "RSU1") 130 and second side unit (Road Side Equipment, hereinafter referred to as "RSU2") 135.

The OBU 110 is a terminal mounted on a vehicle, and can perform radio frequency (RF) signaling or receiving operations with the RSUs 130 and 135 installed on the road side. The above-mentioned vehicle detectors 120, 125 function only to identify the vehicle type, itself and RF It does not matter whether it is sent or received. The above-described OBU 110 will sequentially pass through the first vehicle detector 120, the second vehicle detector 125, the first roadside unit RSU1 130, and the second roadside unit RSU2 135 and complete the steps required for charging.

The section indicated by the arrow in the first figure indicates the communication area 150, and the section can perform a transmission or reception operation between the OBU 110 and the RSUs 130 and 135, and is optimized according to the road condition. And after installing ETCS on the road side, it will not be changed.

The communication area 150 is strictly limited to an area having a certain size in order to minimize the occurrence of an ETCS operation error, and the transmission power and antenna offset of the RSU 130 and 135 can be adjusted according to user requirements. A desired communication area 150 is formed. The communication area 150 may not exceed the position of the first vehicle detector 120, and if the area other than the communication area 150 (for example, the front of the first vehicle detector 120) is between the OBU 110 and the RSU 130, 135 Sending or receiving a job is considered an action error. That is to say, the operation can be regarded as normal only when the transmission or reception operation between the OBU 110 and the RSUs 130 and 135 is performed inside the communication area 150. Therefore, in order to comply with the above-described communication area 150 of the ETCS, the above-described OBU 110 must have good performance, and the lower the reception performance of the OBU 110 for the predetermined communication area 150, the higher the possibility that the ETCS operation error occurs.

Fig. 2 is a view showing a preferred embodiment of a transmitting unit or a receiving unit for a prior electronic charging system.

Referring to FIG. 2, the previous ETCS includes an antenna 100, an RF transmitting and receiving unit 200, and a baseband transmitting and receiving unit 300.

The RF transmitting and receiving unit 200 includes an RF receiving unit 210, an RF transmitting unit 220, and an RF switch 230. The RF receiving unit 210 includes a low noise amplifier 212, a down mixer 214, a filter 216, and an amplitude offset key demodulator 218.

The low noise amplifier 212 described above can amplify the RF signal. The down mixer 214 can down-convert the amplified RF signal to an intermediate frequency (IF) signal. The filter 216 can filter the noise of the down-mixed signal. The amplitude shift keying (ASK) demodulator 218 demodulates the received signal in an ASK manner and outputs a digital signal to the baseband transmitting and receiving unit 300.

The RF transmitting unit 220 includes an upper mixer 222 and a power amplifier 224. The upper mixer 222 can convert the input signal from the baseband transmitting and receiving unit 300 into an RF signal, and the power amplifier 224 can convert the RF signal to have a desired output level. signal.

The second diagram above omits the voltage controlled oscillator (VCO) and the phase locked loop (PLL).

Figure 3 is an illustration of the effect of on-board (OBU) performance on the communication success rate of an electronic toll collection system.

Referring to FIG. 3 and FIG. 1, 350 indicates the minimum communication success rate in the communication area 150, 310 indicates the communication success rate when the OBU 110 transmission performance exceeds the reference, and 330 indicates that the OBU 110 has a lower reception performance. The communication success rate at the time of the reference, 320 indicates the communication success rate when the transmission performance of the OBU 110 conforms to the reference to form an optimization.

The above 350 indicates that the communication success rate of the ETCS terminal is lower than the minimum communication success rate. In this case, the ETCS terminal is considered a fault. The above 310 indicates that the receiving performance of the OBU 110 is good and exceeds the reference, so that the receiving operation is performed in a section other than the communication area, that is, before the position of the vehicle detector 1120.

The above 330 indicates that the receiving performance of the OBU 110 is lower than the reference, and a section 340 in which the communication area internal communication success rate has dropped sharply before leaving the communication area will occur. At this time, if the OBU 110 passes through the ETCS section at a high speed, the possibility of an error increases a lot.

The transmitting performance of the OBU 110 of the above 320 does not exceed the communication area 150, and the section with reduced communication success rate does not appear inside the communication area 150, so that stable performance can be maintained when the OBU 110 passes at a high speed. .

Figure 4 is a diagram showing the output signal of the OBU transmitting unit obtained by reducing the performance of the transmitting part of the previous OBU.

Please refer to FIG. 4 and FIG. 1 . The left picture of FIG. 4 is an output signal diagram of a general OBU transmitting unit. The OBU 110 output signal is a signal demodulated according to the ASK method, and the output value thereof needs to exceed a certain size.

The quality of the output signal described above can be expressed using a modulation index 412, which is the difference between the carrier component amount 410 and the amplitude offset component amount 414. The smaller the difference between the carrier component amount 410 and the amplitude offset component amount 414 is, the better the modulation index 412 is, and the better the quality of the OBU 110 output signal and the OBU 110 transmission performance.

The right diagram of Fig. 4 is an output signal diagram of the OBU 110 transmitting section obtained after the performance of the transmitting section of the OBU 110 is lowered. As can be seen from the above figure, when the magnitude of the amplitude offset component 424 is reduced while the carrier component amount 420 remains unchanged, the modulation index 422 can be lowered. Using the method of reducing the above-mentioned modulation index 422 of the OBU 110 signaling signal The low OBU 110 signaling performance can reduce the receiving performance of the receiving units of the RSUs 130, 135, and thus can limit the communication area 150 between the OBU 110 and the RSUs 130, 135.

The above prior art can obtain the required communication area, but has the following problems.

That is, the action mode of the ETCS with the OBU 110 is that it must be sent as long as the receipt is received. Therefore, the receiving unit performance of the OBU 110 cannot be limited. The receiving unit of the OBU 110 may also recognize that it is a normal receiving signal when receiving the signal before entering the communication area 150, and the transmitting unit of the OBU 110 also outputs. That is, although the communication between the OBU 110 and the RSUs 130, 135 is unsuccessful in the section preceding the communication area, an unnecessary action state is caused, which not only causes the OBU 110 to affect the ETCS performance in areas other than the communication area 150. The noise also reduces the efficiency of the conversion of incoming and outgoing calls when entering the communication area 150 of the OBU 110.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a communication area limiting apparatus for an ETCS terminal that can intelligently control the receiving sensitivity of an ETCS terminal in a limited communication area.

In order to solve the above technical problem, the communication area limiting device of the ETCS terminal of the present invention is applicable to an electronic toll collection system having an antenna, an RF receiving unit, an RF transmitting unit, and an on-board (OBU) of a baseband transmitting and receiving unit, wherein Including the OBU receiving performance limiting device, the OBU receiving performance limiting device has a digital control block and a Received Signal Strength Indication (RSSI) control block, which can be demodulated by an amplitude offset key constituting the RF receiving unit. The receiving end of the device limits the receiving performance of the OBU and performs the sending or receiving operation only in a certain range of communication areas.

The communication area limiting device of the ETCS terminal of the present invention for achieving the above object can be applied to an electronic toll collection system including an antenna, an RF receiving unit, an RF transmitting unit, and an on-board transceiver (OBU) of the baseband transmitting and receiving unit, including an OBU. The receiving performance limiting device, the receiving performance limiting device of the OBU has a digital control block and an RSSI control block, and can limit the above on the receiving end of the amplitude offset key demodulator constituting the RF receiving unit. The receiving performance of the OBU is only performed in a certain range of communication areas for sending or receiving operations.

In order to make the objects, features, and advantages of the present invention more apparent, the following description is made in conjunction with the accompanying drawings.

Fig. 5 is a structural diagram of a communication area limiting device of the ETCS terminal of the present invention.

Referring to FIG. 5 and FIG. 2, the communication area limiting apparatus of the present invention can constitute an electronic unit having an antenna 100, an RF transmitting and receiving unit 200, a baseband transmitting and receiving unit 300, and an OBU terminal memory 400 (OBU). Charging system. In addition to the previous RF receiving unit 210, the RF transmitting unit 220, and the RF switch 230, the RF transmitting and receiving unit 200 further includes a receiving performance limiting device 240 for the vehicle.

The above-described receiving performance limiting means 240 is a circuit corresponding to the characterizing portion of the present invention and can limit the receiving performance of the OBU, including the digital control block 242 and the RSSI control block 244. The RSSI control block 244 is a circuit that can generate a corresponding RSSI output signal according to the size of the received signal, and can be adjusted by the digital control block 242.

The RSSI control block 244 is adjusted by the digital control block 242, and may be based on the adjusted RSSI threshold or the reference receiving sensitivity. The output signal of the amplitude shift key demodulator 218 is adjusted by a good signal value. The above output signal is transmitted to the baseband transmitting and receiving section 300. At this time, the optimum digital control value of the RSSI threshold or the reference receiving sensitivity is stored in the OBU terminal memory 400.

The antenna 100, the RF transmitting and receiving unit 200, and the baseband transmitting and receiving unit 300 have been described in FIG. 2 and will not be described in detail herein.

Figure 6 is a block diagram showing the RSSI of the operation performance of the OBU of the present invention.

Referring to Figures 6 and 5, 610 represents the reference reception sensitivity of the OBU, 611 represents the RSSI, 620 represents the RSSI threshold (RSSIth), and 613 represents the RSSI slope (Slope). When the above-described reference reception sensitivity 610 is applied between individual OBUs, it is necessary to maintain a very small reception sensitivity deviation. The RSSI threshold 620 is a reference value that can measure whether the OBU receive signal size is greater or less than the RSSI threshold 620 and can be adjusted by the RSSI control block 244.

Figure 7 is the RSSI and the ASK output signal after Demodulation generated by the OBU's receiving performance operation of the present invention.

Referring to Figures 7 and 5, 610 represents the reference reception sensitivity (Pref) of the OBU, 730 represents the RSSI, and 740 represents the ASK output signal after the Demodulation.

The RSSI 730 is generated by the RSSI control block 244. When the receiving signal is greater than the corresponding RSSI threshold RSSIth1 of the reference receiving sensitivity 610, it becomes a logic high level, and the size of the receiving signal is lower than the RSSI threshold RSSIth1. Level.

The output signal 740 is output only when the received signal size of the OBU is greater than the corresponding RSSI threshold RSSIth2 of the reference receiving sensitivity 610. The output signal is not generated when the size of the received signal is less than the RSSI threshold RSSIth2.

The communication area limiting device of the present invention described above is applicable to the OBU in the embodiment, and may be applied to the RSU as needed, which is very obvious. When the communication area limiting device is applied to the RSU, the OBU mode described in the above FIGS. 5 to 7 can be used, that is, the communication area of the RSU can be restricted by adjusting the RSSI inclination 611 or the RSSI threshold RSSIth. Therefore, it will not be explained in detail.

In summary, it can be summarized as follows.

First, the user can adjust the RSSI slope 611 and the RSSI threshold RSSIth2 through the RSSI control block 244 adjusted by the digital control block 242 to finely adjust the OBU's receiving sensitivity to a desired level. Therefore, the sending and receiving operation between the OBU and the RSU is restricted inside the communication area 150.

Second, the RSSI control block 244 can be controlled as follows by virtue of the RSSI 630 function. For an input signal below the reference reception sensitivity 610, the demodulated output signal is not generated at the receiving portion of the OBU, and the OBU output output signal is generated only when the reference reception sensitivity 610 is greater than the reference.

Third, the communication area limiting device of the present invention is adjusted by the digital control mode, so that the automatic correction function can be realized when the OBU is produced, and the RSSI threshold or the reference receiving sensitivity obtained by the experimental method can be optimized in the OBU production process. The digital control value is stored in the OBU terminal memory 400, so it can be easily operated.

Fourth, the above-mentioned communication area limiting device is applicable not only to the OBU but also to the RSU, and the foregoing method applicable to the OBU can be used.

The present invention has been described in detail with reference to the preferred embodiments of the present invention, and is not intended to limit the scope of the invention, and the invention may be variously modified and modified without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100‧‧‧Antenna

110‧‧‧Car machine

120‧‧‧First Vehicle Detector

125‧‧‧Second vehicle detector

130‧‧‧First roadside unit

135‧‧‧Second roadside unit

150‧‧‧Communication area

200‧‧‧RF receiving and receiving department

210‧‧‧RF receiving department

212‧‧‧Low noise amplifier

214‧‧‧Down Mixer

216‧‧‧ filter

218‧‧‧Amplitude offset key demodulator

220‧‧‧RF Transmitting Department

222‧‧‧Upmixing

224‧‧‧Power Amplifier

230‧‧‧RF switch

240‧‧‧Receiving performance limiting device

242‧‧‧Digital Control Block

244‧‧‧RSSI control block

300‧‧‧Based Frequency Receiving Department

Section 340‧‧‧

400‧‧‧OBU terminal memory

410‧‧‧ Carrier weight

412‧‧‧Transformation index

414‧‧‧Amplitude offset weight

422‧‧‧Transformation index

424‧‧‧ offset amount

610‧‧‧Reference sensitivity

611‧‧‧ Received Signal Strength Indicator (RSSI)

620‧‧‧RSSI threshold

613‧‧‧RSSI inclination

730‧‧‧ Received Signal Strength Indicator (RSSI)

740‧‧‧ASK output signal

Figure 1 is a general structural diagram of an electronic toll collection system (ETCS).

Fig. 2 is a view showing a preferred embodiment of a transmitting unit or a receiving unit for a prior electronic charging system.

Figure 3 is an explanatory diagram of the effect of the performance of the on-board machine (OBU) on the communication success rate of the electronic toll collection system.

Figure 4 is a diagram showing the output signal of the OBU transmitting unit obtained by reducing the performance of the transmitting part of the previous OBU.

Fig. 5 is a structural diagram of a communication area limiting device of the ETCS terminal of the present invention.

Figure 6 is a block diagram showing the RSSI of the operation performance of the OBU of the present invention.

Figure 7 is the RSSI and the ASK output signal after Demodulation generated by the OBU's receiving performance operation of the present invention.

100‧‧‧Antenna

200‧‧‧RF receiving and receiving department

210‧‧‧RF receiving department

212‧‧‧Low noise amplifier

214‧‧‧Down Mixer

216‧‧‧ filter

218‧‧‧Amplitude offset key demodulator

220‧‧‧RF Transmitting Department

222‧‧‧Upmixer

224‧‧‧Power Amplifier

230‧‧‧RF switch

240‧‧‧Receiving performance limiting device

242‧‧‧Digital Control Block

244‧‧‧ Received Signal Strength Indication Control Block

300‧‧‧Based Frequency Receiving Department

400‧‧‧OBU terminal memory

Claims (10)

An communication area limiting device for an electronic toll collection system (ETCS) terminal, which is suitable for an on-board machine having an antenna, a radio frequency (RF) receiving unit, an (RF) transmitting unit, and a base frequency transmitting and receiving unit (OBU) an electronic toll collection system, further comprising: an OBU receiving performance limiting device, the OBU receiving performance limiting device having a digital control block and a Received Signal Strength Indication (RSSI) control block, A receiving end of the amplitude offset key demodulator constituting one of the RF receiving sections limits the receiving performance of the OBU and performs a signaling or receiving operation only in a communication area of a certain range. The communication area limiting device of the ETCS terminal according to claim 1, wherein the RSSI control block adjusts an RSSI threshold or an RSSI inclination to control the amplitude offset modulation demodulator to generate The amplitude shift key produces an output signal. The communication area limiting device of the ETCS terminal according to claim 2, wherein the amplitude offset key output signal is only at a corresponding reference receiving sensitivity of one of the OBU receiving signal input strengths greater than the RSSI threshold. Will only output. The communication area limiting device of the ETCS terminal according to claim 1, wherein the RF transmitting unit transmits the transmission signal only when the corresponding reference receiving sensitivity is greater than the RSSI threshold. The communication area limiting apparatus of the ETCS terminal according to claim 1, wherein one of the digital control values for storing the RSSI threshold or the reference receiving sensitivity is additionally disposed at one end of the base frequency transmitting and receiving unit. OBU terminal memory. A communication area limiting device for an ETCS terminal, which is suitable for having an antenna, an RF receiving unit, an RF transmitting unit, and a base frequency transmitting and receiving unit installed on each roadside unit (RSU) The system, further comprising: an RSU receiving performance limiting device, the RSU receiving performance limiting device having a digital control block and a Received Signal Strength Indication (RSSI) control block, which may constitute an amplitude of the RF receiving portion The receiving end of the offset modulation demodulator limits the receiving performance of the roadside unit (RSU) and performs signaling or receiving operations only in a certain range of communication areas. The communication area limiting device of the ETCS terminal according to claim 6, wherein the RSSI control block adjusts an RSSI threshold or an RSSI inclination to control the amplitude offset modulation demodulator to generate An amplitude shift key produces an output signal. The communication area limiting device of the ETCS terminal according to claim 6, wherein the amplitude offset key output signal is only at a corresponding reference receiving sensitivity of one of the OBU receiving signal input strengths greater than the RSSI threshold. Will only output. The communication area limiting device of the ETCS terminal according to claim 6, wherein the RF transmitting unit transmits the transmission signal only when the corresponding reference receiving sensitivity is greater than the RSSI threshold. The communication area limiting device of the ETCS terminal according to claim 6, wherein an RSU capable of storing one of the RSSI threshold or the reference receiving sensitivity digital control value is additionally disposed at one end of the baseband transmitting and receiving unit. Terminal memory.