JP2013098772A - Communication device, automatic toll collection system, and automatic toll collection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly reliable device by avoiding incorrect link establishment with a terminal in a non-communication area.SOLUTION: A communication device comprises: an array antenna 2 composed of a plurality of element antennas 21-1 to 21-N for receiving a signal from a terminal; beam formation means 3 for adjusting excitation amplitude phase values of the received signal from the element antennas 21-1 to 21-N by using predetermined excitation coefficient values, and synthesizing the adjusted values; control means 4 for performing setting change of the excitation coefficient values so as to change a level reduction direction of an antenna pattern formed by the array antenna 2 in a non-communication area, every time the array antenna 2 receives a link establishment request signal from the terminal; and communication processing means 6 for determining the propriety of communication link establishment with the terminal on the basis of an output signal from the beam formation means 3.

Description

  The present invention relates to a communication apparatus that is applied to a base station that communicates with a terminal and that avoids erroneous link establishment with a terminal in a non-communication area. In particular, the fare is automatically charged between a roadside machine (base station) installed at a toll booth and a vehicle equipped with a terminal having an automatic toll collection function, without temporarily stopping the vehicle traveling on the road. The present invention relates to an automatic fee collection system and an automatic fee collection method.

In a conventional automatic fee collection system, a vehicle is equipped with a wireless communication device (on-vehicle device) and an electronic payment means such as an IC card. In addition, a dedicated lane for automatic toll collection or a mixed lane with ordinary vehicles is installed at a toll gate on a toll road, and a wireless communication device (roadside device) for communicating with an in-vehicle device mounted on the vehicle is provided.
However, in the automatic toll collection system, there is a concern that normal charges cannot be collected due to oversight of a traveling vehicle not equipped with an in-vehicle device corresponding to the automatic toll collection system or failure to follow the traveling vehicle due to a lane change. It was. Therefore, as one of the countermeasures, there is a technique for estimating the traveling direction of a vehicle from a wireless communication signal from an in-vehicle device by installing an array antenna having a plurality of element antennas installed on a roadside device (for example, Patent Document 1). 2). As a result, it is possible to reliably perform the receiving process with the traveling vehicle equipped with the in-vehicle device.

JP 2001-34799 A JP 2002-243825 A

However, with the recent spread, the number of vehicles equipped with compatible in-vehicle devices is rapidly increasing, and the system is being used everywhere. In such a situation, there is an increased possibility that a plurality of automatic toll collection systems operate in an area where a plurality of toll roads are adjacent. In general, the vicinity of such an area is a complex propagation environment in which many structures are arranged. For this reason, a situation occurs in which a radio communication signal from an in-vehicle device mounted on a vehicle traveling on the adjacent road that crosses the vehicle passes over the roadside belt or viaduct and arrives at the roadside device. Therefore, a wireless communication signal from a vehicle in a non-communication area is erroneously detected, and there is a problem that normal charge collection processing may not be performed.
For example, in a complex road environment such as a junction where a plurality of toll roads intersect, many multipaths arrive. For this reason, in the conventional method using the instantaneous direction estimation value of the wireless communication signal, the reliability of the estimated value is remarkably lowered and may not be applied in an actual environment.

  The present invention has been made to solve the above problems, and determines whether or not a communication link can be established from the result of receiving a signal requesting establishment of a communication link coming from a terminal multiple times with different antenna patterns. A highly reliable communication device capable of avoiding erroneous link establishment with a terminal in a non-communication area, and a highly reliable automatic fee collection system and automatic fee collection to which this is applied. It aims to provide a method.

  The communication apparatus according to the present invention adjusts the excitation amplitude phase value of the received signal from the element antenna by using an array antenna composed of a plurality of element antennas for receiving a signal from the terminal and a predetermined excitation coefficient value, Each time the array antenna receives a link establishment request signal from the terminal, the excitation coefficient value setting is changed so that the level reduction direction in the non-communication area of the antenna pattern formed by the array antenna is changed. And a communication processing unit that determines whether or not a communication link with the terminal can be established based on an output signal from the beam forming unit.

  According to this invention, since it comprised as mentioned above, the reliable communication apparatus which can avoid the erroneous link establishment with the terminal of a non-communication area can be obtained. In addition, a highly reliable automatic fee collection system and automatic fee collection method to which this is applied can be obtained.

It is a figure which shows the structural example of the communication apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the structural example of the beam formation part in Embodiment 1 of this invention. It is a figure which shows the example of calculation of the antenna pattern in Embodiment 1 of this invention, and the minimum gain value (minimum receiving sensitivity). It is a figure which shows the example of control of the antenna pattern in Embodiment 1 of this invention. It is a figure which shows the structural example of the automatic fee collection system to which the communication apparatus which concerns on Embodiment 2 of this invention is applied. It is a figure which shows the example of a frame structure used with the automatic fee collection system which concerns on Embodiment 2 of this invention. It is a flowchart which shows the determination processing of the automatic fee collection system which concerns on Embodiment 2 of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a communication apparatus 1 according to Embodiment 1 of the present invention. In addition, in each figure, the same code | symbol shows the same or equivalent part.
As shown in FIG. 1, the communication device 1 includes an array antenna 2 including N element antennas 21-1 to 21 -N, a beam forming unit (beam forming unit) 3, a control unit (control unit) 4, and an excitation coefficient. The storage unit (excitation coefficient storage unit) 5, the communication processing unit (communication processing unit) 6, and the receipt processing unit (acquisition processing unit) 7 are configured.

  The array antenna 2 forms a predetermined antenna pattern by exciting the element antennas 21-1 to 21-N with a predetermined amplitude and phase value, and receives a radio communication signal from an external terminal. Reception signals from the element antennas 21-1 to 21 -N are output to the beam forming unit 3.

  The beam forming unit 3 uses the excitation coefficient value from the control unit 4 to adjust the excitation amplitude phase value of the received signal from each of the element antennas 21-1 to 21-N and synthesizes it. The internal configuration of the beam forming unit 3 will be described later. The signal synthesized by the beam forming unit 3 is output to the communication processing unit 6 as an antenna output signal.

  Each time the control unit 4 receives an instruction to change the excitation coefficient value from the communication processing unit 6, the control unit 4 changes the setting of the excitation coefficient value used in each of the element antennas 21-1 to 21-N. Here, the control unit 4 changes the setting by acquiring a predetermined excitation coefficient value from the excitation coefficient storage unit 5.

  The excitation coefficient storage unit 5 stores a plurality of excitation coefficient values in advance. Each excitation coefficient value stored in the excitation coefficient storage unit 5 is a value set such that the directions of the zeros in the non-communication area of the antenna pattern formed by the array antenna 2 are different from each other. Based on the original, it may be obtained in advance or at the stage of local adjustment. Here, the excitation coefficient storage unit 5 outputs a different excitation coefficient value to the control unit 4 every time an instruction to change the excitation coefficient value is received from the communication processing unit 6.

The communication processing unit 6 determines whether or not a communication link can be established with a terminal that has requested establishment of a communication link based on an antenna output signal from the beam forming unit 3 and performs various communication processes. In addition, when the antenna output signal is a link establishment request signal from the terminal, the communication processing unit 6 instructs the control unit 4 and the excitation coefficient storage unit 5 to change the excitation coefficient value in synchronization therewith. . Note that the link establishment request signal from the terminal is transmitted a plurality of times in order to improve certainty.
The receipt processing unit 7 is configured to perform specific processing such as billing using an antenna output signal from the beam forming unit 3 with a terminal that has been permitted to establish a communication link by the communication processing unit 6 and has performed various types of communication processing. Is to implement.

Next, the configuration of the beam forming unit 3 will be described. FIG. 2 is a diagram showing a configuration example of the beam forming unit 3 according to Embodiment 1 of the present invention.
The beam forming unit 3 includes N multipliers 31-1 to 31 -N and a combiner 32.

The multipliers 31-1 to 31 -N use the excitation coefficient values from the control unit 4 to perform complex multiplication on the received signals from the corresponding element antennas 21-1 to 21 -N, thereby It is an arithmetic circuit for adjusting the excitation amplitude phase value. The multipliers 31-1 to 31 -N can be realized by a variable attenuator and a variable phase shifter in the case of an analog device. The signals subjected to complex multiplication by the multipliers 31-1 to 31 -N are output to the synthesizer 32.
The synthesizer 32 synthesizes the signals from the multipliers 31-1 to 31 -N. The signal synthesized by the synthesizer 32 is output to the communication processing unit 6 as an antenna output signal.

Next, specific processing of the communication apparatus 1 configured as described above will be described.
In the base station to which the communication device 1 is applied, it is necessary to form an antenna pattern suitable for the communication area. And in the array antenna 2 which consists of several element antennas 21-1 to 21-N as shown in FIG. 1, the amplitude phase value which excites each element antenna 21-1 to 21-N is set appropriately. The antenna pattern can be changed freely. At this time, the antenna gain is maintained so that the communication area has a constant electric field level, and the side lobe level is reduced as much as possible to avoid unnecessary radiation (interference) to adjacent areas (non-communication areas). There is a need to.

  For example, FIG. 3A shows an example of calculating an antenna pattern when an omnidirectional linear array having 8 elements is used. FIG. 3A shows four antenna patterns of Beams 1 to 4, and the antenna gain within ± 30 degrees which is a communication area is made as constant as possible. Moreover, although the side lobe level of each antenna pattern calculation value is about -20 to -25 dB, it cannot be said to be sufficient. However, since the antenna size or the number of element antennas is limited due to restrictions such as limited installation locations, it is difficult to sufficiently reduce the side lobe level in all directions at a specific time (instant). . In this case, there is a risk that a signal from an in-vehicle terminal such as an adjacent lane or an adjacent road is erroneously detected due to the influence of surrounding structures and the like, and communication processing is performed. Actually, it is possible to detect such erroneous communication on the network side and stop the final processing, but as long as the communication link is established, extra resources will be wasted, This leads to a decrease in communication traffic.

On the other hand, FIG. 3B is a plot of the minimum gain values (minimum reception sensitivity) of the four antenna patterns shown in FIG. As shown in FIG. 3B, it can be seen that with the minimum reception sensitivity, the reception level in the non-communication area direction is significantly reduced while maintaining the gain of the communication area within ± 30.

Utilizing the above principle, the communication device 1 according to Embodiment 1 has a feature of controlling the antenna pattern so as not to establish a communication link with a terminal in a non-communication area.
That is, every time the array antenna 2 receives a link establishment request signal from a terminal, the control unit 4 changes the setting of the excitation coefficient values used in the multipliers 31-1 to 31 -N. At this time, the excitation coefficient value is set and changed so as to change the level reduction direction in the non-communication area of the antenna pattern (so as to move the zero point direction and level of the side lobe). For example, as shown in FIGS. 4A to 4D, the zero point of the antenna pattern is shifted from the inside to the outside by changing the antenna pattern from Beam 1 shown in FIG. 3A to Beam 4 in order. Thereby, the reception level of the terminal signal from the non-communication area can be reduced in a time division manner, and as a result, a reception signal (minimum reception level) with the minimum reception sensitivity as shown in FIG. 3B can be obtained.
Note that the order of shifting the zero points of the antenna pattern is not limited to the example shown in FIG.

The communication processing unit 6 makes a determination based on the minimum reception sensitivity, thereby greatly reducing the probability (false determination probability) of establishing a communication link with a terminal in a non-communication area. At this time, for example, when the minimum reception level of each link establishment request signal is equal to or higher than a predetermined threshold, link establishment with the terminal is permitted. Moreover, when the number of times that is equal to or greater than the threshold among the respective reception levels is equal to or greater than a set value, establishment of a communication link with the terminal may be permitted.
After that, the receipt processing unit 7 performs specific processing such as billing with the terminal determined by the communication processing unit 6 as a terminal in the communication area.

  As described above, according to the first embodiment, the excitation coefficient value is changed every time a link establishment request signal transmitted from the terminal is received a plurality of times, and each element antenna 21-1 is used by using this value. Since it is configured to determine whether or not the communication link with the terminal can be established based on the signal synthesized by adjusting the excitation amplitude phase value of the received signal from 21-N, the side lobe level can be reduced by time division. And a highly reliable communication device 1 that can avoid erroneous link establishment with a terminal in a non-communication area can be obtained. And, by applying to existing communication systems, it is possible to realize high-accuracy link establishment processing even in complex propagation environments such as multipath waves, and realize a system that completes communication processing by a base station alone be able to.

  In the first embodiment, the configuration is such that the excitation amplitude and phase values of the received signals from all the element antennas 21-1 to 21-N are adjusted. It is also possible to change the antenna pattern shape by adjusting only the excitation amplitude phase value of the received signal from the element antenna located at the end. In this case, since the number to be adjusted can be reduced, the calculation scale can be reduced.

Embodiment 2. FIG.
FIG. 5 is a diagram showing a configuration example of an automatic fee collection system to which the communication device 1 according to Embodiment 2 of the present invention is applied. In addition, in each figure, the same code | symbol shows the same or equivalent part.
As shown in FIG. 5, the automatic toll collection system includes a terminal 53 mounted on a vehicle 52 traveling on a road 51 and a base station 54 installed on the road side of the road 51. The base station 54 has a configuration equivalent to that of the communication device 1 shown in FIG. 1, such as the array antenna 2 that receives radio communication signals.
In the communication area 55, the terminal 53 and the base station 54 implement various services such as toll collection processing by radio communication signals (uplink 60, downlink 61) using a frequency in the microwave band.

Next, specific processing of the automatic fee collection system configured as described above will be described below.
The base station 54 transmits and receives radio communication signals 60 and 61 to and from the terminal 53 via the array antenna 2 and performs a road usage fee collection process. On the other hand, as a surrounding environment, a vehicle 58 equipped with a terminal 57 is traveling on the adjacent road 56. Depending on the surrounding radio wave propagation environment, the wireless communication signal 62 from the terminal 57 may jump over the roadside band 59 existing between the roads 51 and 56 and arrive at the base station 54. At this time, it is necessary for the base station 54 to determine the traveling vehicle so as not to mistakenly collect the terminal 57.

  Here, if the environment includes only the direct waves (wireless communication signals 60 and 62) from the vehicle-mounted terminals 53 and 57 as shown in FIG. 5, it can be identified by an existing direction estimation method or the like. However, in an environment where there are many structures that reflect and scatter radio waves, such as the roadside band 59, viaduct, and the gate that supports the base station 54, the direction estimation value usually varies because many multipath waves arrive. Is expected. That is, the accuracy of the instantaneous direction estimation value is not very likely. Further, although it is conceivable to sufficiently reduce the side lobe level of the array antenna 2, there are limitations when considering installation space and manufacturability, and it is difficult to cope with only a certain fixed antenna pattern.

  Therefore, the communication link establishment with the terminal 57 in the non-communication area is avoided by adapting the antenna pattern control of the first embodiment to the communication link establishment procedure in the automatic fee collection system.

FIG. 6 is a diagram showing a frame configuration example used in the automatic fee collection system according to Embodiment 2 of the present invention.
As shown in FIG. 6, in the downlink from the base station 54 to the terminal, a frame control message slot (FCMS) for notifying the terminal of slot allocation information, frame control information, and the like is positioned at the head, and then a message data slot ( MDS) is multiplexed by the number of terminals. FIG. 6 shows a case where the number of terminals is three.

  On the other hand, in the uplink from the terminal to the base station 54, an activation slot (ACTS) for the terminal to register with the communication link of the base station 54 is arranged after the MDS. In this ACTS, six activation channel (ACTC) windows are arranged. During the link establishment phase, the terminal 53 selects one of these windows and transmits the ACTC to the base station 54. The uplink and downlink channels are multiplexed by using different frequencies.

  Normally, six channels (communicable with a maximum of six terminals) are transmitted as ACTC, and the base station 54 determines whether or not a communication link can be established based on the reception levels of those signals. Therefore, in the automatic toll collection system according to the second embodiment, the reception level of the terminal signal coming from the non-communication area is reduced by changing the antenna pattern in the communication apparatus 1 in FIG. 1 for each ACTC or each ACTS, for example. To do.

Next, a specific determination process of the toll collection target vehicle by the base station 54 will be described. FIG. 7 is a flowchart showing determination processing of the automatic fee collection system according to Embodiment 2 of the present invention.
As shown in FIG. 7, first, the base station 54 sends a message notification to the terminal by FCMS (step ST71).
Next, in the terminal that has received this message, an ACTC is selected according to a predetermined criterion, and a link establishment request signal (for example, ACTC) is transmitted in the window (step ST72).

  On the other hand, the control unit 4 of the base station 54 sets an excitation coefficient value for adjusting the excitation amplitude phase value of the received signals from the element antennas 21-1 to 21-N (step ST73, control step). Next, the link establishment request signal from the terminal is received, and the beam forming unit 3 adjusts the excitation amplitude phase value of each reception signal using the set excitation coefficient value, and then combines (step ST74, reception). Step, beam forming step). This transmission / reception process is performed a plurality of times (N times in FIG. 7) (steps ST75 to ST77).

  Thereafter, the communication processing unit 6 of the base station 54 determines whether or not the minimum reception level of each reception signal is equal to or greater than a certain threshold (step ST78, communication processing step). In addition, about the method of determining a threshold value, radio waves may be measured in advance at an actual site to obtain a standard, or analytically obtained by simulation. It is also possible to adjust to an appropriate value during operation.

  Here, when determining that the minimum reception level is smaller than the threshold, the communication processing unit 6 determines that the signal is from a terminal existing in the non-communication area, and stops the communication process (step ST79). That is, for example, in the wireless communication signal 62 from the terminal 57 of the vehicle 58 traveling on the adjacent road 56, the minimum reception level is smaller than the threshold value, and it is determined that the terminal is in the non-communication area.

On the other hand, when determining that the minimum reception level is equal to or higher than the threshold, the communication processing unit 6 determines that the signal is a signal from a terminal in the communication area 55 and notifies the terminal of link establishment (step ST80). ). That is, for example, in the wireless communication signal 60 from the terminal 53 of the vehicle 52 traveling on the road 51, the minimum reception level is equal to or higher than the threshold value, and it is determined that the terminal is in the communication area 55. Note that the communication processing unit 6 may allow the communication link establishment with the terminal to be permitted when the number of times that is equal to or greater than the threshold among the respective reception levels is equal to or greater than the set value.
Thereafter, the base station 54 starts communication with the terminal (step ST81), and the toll processing unit 7 of the base station 54 performs toll processing such as billing, and the processing is completed (steps ST82 and ST83, toll processing). Step).

  As described above, according to the second embodiment, an automatic fee provided with a terminal mounted on a moving body such as the vehicle 52 and a base station 54 that communicates with the terminal 53 and automatically receives the fee. In the toll system, the base station 54 changes the excitation coefficient value every time it receives an ACTC transmitted from the terminal a plurality of times, and uses this value to change the received signal from each element antenna 21-1 to 21-N. Since it is configured to determine whether or not a communication link with a terminal can be established based on a signal synthesized by adjusting the excitation amplitude and phase value, it is possible to avoid erroneous link establishment with the terminal 57 in a non-communication area. A highly reliable automatic toll collection system can be obtained. In addition, it is possible to realize a system that efficiently completes the receiving process by the base station alone without complicating the system, such as a large antenna or a highly accurate direction finding device.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  1 communication device, 2 array antenna, 3 beam forming unit (beam forming unit), 4 control unit (control unit), 5 excitation coefficient storage unit (excitation coefficient storage unit), 6 communication processing unit (communication processing unit), 7 receiving Processing unit (acquisition processing means), 21-1 to 21-N element antenna, 31-1 to 31-N multiplier, 32 combiner, 51 road, 52,58 vehicle, 53,57 terminal, 54 base station, 55 Communication area, 56 adjacent road, 59 roadside band, 60 uplink, 61 downlink, 62, 63 wireless communication signals.

Claims (14)

An array antenna composed of a plurality of element antennas for receiving signals from the terminal;
Beam forming means for adjusting and synthesizing the excitation amplitude phase value of the received signal from the element antenna using a predetermined excitation coefficient value; and
Control means for changing the setting of the excitation coefficient value so that the level reduction direction in the non-communication area of the antenna pattern formed by the array antenna is changed each time the array antenna receives a link establishment request signal from the terminal. When,
A communication apparatus comprising: a communication processing unit that determines whether or not a communication link with the terminal can be established based on an output signal from the beam forming unit. The communication apparatus according to claim 1, wherein the communication processing unit determines whether or not a communication link can be established with the terminal based on a reception level of each link establishment request signal. The communication apparatus according to claim 2, wherein the communication processing unit permits establishment of a communication link with the terminal when the number of times that the reception level is equal to or greater than a threshold value is equal to or greater than a set value. The communication apparatus according to claim 2, wherein the communication processing unit permits establishment of a communication link with the terminal when a minimum value among the reception levels is equal to or greater than a threshold value. Comprising excitation coefficient storage means for storing a plurality of excitation coefficient values in which the zeros in the non-communication areas of the antenna pattern formed by the array antenna are in different directions,
5. The communication according to claim 1, wherein the control unit changes the setting by acquiring a predetermined excitation coefficient value stored in the excitation coefficient storage unit. 6. apparatus. The communication according to any one of claims 1 to 5, wherein the beam forming unit adjusts an excitation amplitude phase value of a reception signal from the element antenna located at an end portion of the antenna opening. apparatus. In an automatic fee collection system comprising a terminal mounted on a mobile body and a base station that automatically collects a fee by communicating with the terminal,
The base station
An array antenna composed of a plurality of element antennas for receiving signals from the terminal;
Beam forming means for adjusting and synthesizing the excitation amplitude phase value of the received signal from the element antenna using a predetermined excitation coefficient value; and
Control means for changing the setting of the excitation coefficient value so that the level reduction direction in the non-communication area of the antenna pattern formed by the array antenna is changed each time the array antenna receives a link establishment request signal from the terminal. When,
Communication processing means for determining whether or not a communication link with the terminal can be established based on an output signal from the beam forming means;
An automatic fee collection system comprising: a receipt processing unit that collects a fee using an output signal from the beam forming unit with a terminal that is permitted to establish a communication link by the communication processing unit. 8. The automatic fee collection system according to claim 7, wherein the link establishment request signal is an activation channel or an activation slot. 8. The automatic fee collection system according to claim 7, wherein the communication processing unit determines whether or not a communication link with the terminal can be established based on a reception level of each link establishment request signal. The automatic fee collection system according to claim 9, wherein the communication processing unit permits establishment of a communication link with the terminal when the number of times that the reception level is equal to or greater than a threshold value is equal to or greater than a set value. The automatic fee collection system according to claim 9, wherein the communication processing unit permits establishment of a communication link with the terminal when a minimum value among the reception levels is equal to or greater than a threshold value. Comprising excitation coefficient storage means for storing a plurality of excitation coefficient values in which the zeros in the non-communication areas of the antenna pattern formed by the array antenna are in different directions,
The automatic control according to any one of claims 7 to 11, wherein the control means changes the setting by acquiring a predetermined excitation coefficient value stored in the excitation coefficient storage means. Toll collection system. 13. The automatic according to claim 7, wherein the beam forming unit adjusts an excitation amplitude phase value of a reception signal from the element antenna located at an end portion of the antenna opening. Toll collection system. In an automatic fee collection method by an automatic fee collection system comprising a terminal mounted on a mobile body and a base station that automatically collects a fee by communicating with the terminal,
The base station
A receiving step of receiving a signal from a terminal by a plurality of element antennas constituting the array antenna;
A beam forming step of adjusting and synthesizing the excitation amplitude phase value of the received signal from the element antenna using a predetermined excitation coefficient value; and
A control step of changing the setting of the excitation coefficient value so that the level reduction direction in the non-communication area of the antenna pattern formed by the array antenna is changed each time the array antenna receives a link establishment request signal from the terminal. When,
A communication processing step for determining whether or not a communication link with the terminal can be established based on an output signal in the beam forming step;
An automatic fee collection method, comprising: a toll collection step of collecting a fee with a terminal permitted to establish a communication link in the communication processing step using an output signal in the beam forming step.

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