JP2005229300A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system capable of preventing unnecessary communication with a mobile station which exists outside of a radio communication radio range to be communicated and to which the communication is prohibited originally by detecting whether or not reflected radio comes from a moving object with a comparatively simple configuration. <P>SOLUTION: A plurality of (2, e.g.) base stations are arranged so as to form overlapped radio communication radio ranges by forming the same radio wave radiation area at a distance of some degree. Then, depending on whether or not response wave from the mobile station can be received by all of the plurality of base stations, it is determined whether the response wave comes from the mobile station in the radio communication radio range or from another. Then the communication is continued or interrupted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

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

However, in the above-described conventional ETC system using narrow-area wireless communication, when a vehicle enters the wireless communication radio wave area, the radio wave from the base station is reflected on the vehicle itself, and is moved to a place other than the radio communication radio wave area. Radio waves may leak, and communication may occur with mobile stations that should not be able to communicate with each other.
Moreover, in order to solve such a problem, for example, by using two or more antennas in the base station, a method of detecting the direction from the phase difference of the radio wave received by each antenna, or simply the reception power of each antenna However, there is a possibility that the direction of reflection of radio waves may be erroneously detected, which is inferior in practicality.

  Therefore, the present invention detects whether the radio wave is a reflected radio wave from a mobile object with a relatively simple configuration, and does not need to communicate with a mobile station that should not communicate with a radio communication radio wave that exists outside the radio communication range to be communicated. An object of the present invention is to provide a wireless communication system that can prevent communication.

  The wireless communication system of the present invention includes a plurality of base stations arranged to form overlapping wireless communication radio spheres by forming the same radio wave irradiation region with respect to a predetermined position of a moving path on which a mobile body moves, A mobile station that is mounted on the mobile body and starts communication with the base station by transmitting a response radio wave to the interrogation radio wave from the base station when entering the radio communication radio wave range, and Determination means for determining whether or not response radio waves from the mobile station have been received in all of the plurality of base stations, and as a result of determination by the determination means, response radio waves from the mobile stations in all of the plurality of base stations. The mobile station determines that the mobile station is within the radio communication radio wave range, starts subsequent communication, and receives response radio waves from the mobile station in all of the plurality of base stations. Can't If, the mobile station and a control means for controlling so as not to perform the subsequent communication it is determined that the mobile station that does not exist in the wireless communication waves within.

  According to the present invention, it is possible to detect whether a radio wave is reflected from a mobile body with a relatively simple configuration, and to eliminate unnecessary communication with a mobile station that should not communicate with a radio communication radio wave that exists outside the target radio communication range. A wireless communication system capable of preventing communication can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a configuration of an ETC system as a radio communication system according to an embodiment of the present invention. In FIG. 1, a vehicle (automobile) 1 that is a moving body is equipped with a mobile station (on-vehicle device) 2, for example, a traveling path (moving path) 3 toward a toll gate on a toll road (highway). Is assumed to travel in the direction of the arrow in the figure.

  Base stations 4 and 5 are respectively disposed on both sides of a predetermined position (for example, a gate existing position) of the travel path 3. The base stations 4 and 5 are provided with antennas 4a and 5a for performing communication with the mobile station 2, and the same radio wave irradiation areas 6a and 6b are formed on the traveling path 3 as shown in the figure. Arranged so as to form overlapping radio communication radio spheres 7.

  Each of the base stations 4 and 5 is connected to a determination unit 8 as a determination unit. The determination unit 8 determines whether each of the base stations 4 and 5 has received a response radio wave from the mobile station 2 based on the reception results of the base stations 4 and 5, It is determined whether or not the received power of each response radio wave has reached a predetermined value.

  The determination unit 8 is connected to a control unit 9 as control means. For example, the control unit 9 is configured mainly by a CPU (Central Processing Unit) or the like, and based on the determination result of the determination unit 8, the response radio wave from the mobile station 2 in the radio communication radio wave zone 7 or otherwise The base station 4 or 5 controls communication processing, or collects charges.

  With such a configuration, the vehicle 1 (mobile station 2) normally enters the radio communication radio wave zone 7 as shown in FIG. 2, and the response from the mobile station 2 to the interrogation radio waves from the base stations 4 and 5 The radio wave 10 can be received by the base stations 4 and 5 forming the radio communication radio wave zone 7, respectively.

  However, as shown in FIG. 3, the radio wave reflected from the side surface of the vehicle 1 in the radio communication radio wave area 7 from the optical reflection path characteristic is one base station that forms the radio communication radio wave area 7, for example, as shown in FIG. In many cases, only the inquiry radio wave 11 from the base station 5 is used in the example, and the response radio wave 12 from the mobile station 2a mounted on the vehicle 1a that responds to the reflected radio wave and is not supposed to communicate originally passes through the same route. Reflecting and reaching only one base station, for example, the base station 5 in the example of FIG. 3, the mobile station 2 a can be determined as a mobile station outside the radio communication radio wave range 7.

Next, a first communication control example using such optical reflection path characteristics will be described with reference to the flowchart shown in FIG.
First, polling signals (question radio waves) are transmitted from the base stations 4 and 5 (step S1). Next, the determination unit 8 determines whether each of the base stations 4 and 5 has received a response radio wave from the mobile station based on the reception results of the base stations 4 and 5 (step S2).

  As a result of this determination, when the response radio wave from the mobile station 2 can be received in each of the base stations 4 and 5, the control unit 9 determines that the mobile station 2 is a mobile station existing in the radio communication radio wave zone 7. The base stations 4 and 5 are controlled so as to start communication with the mobile station 2 (step S3).

  As a result of the determination in step S2, if the response radio wave from the mobile station 2 cannot be received in each of the base stations 4 and 5, the control unit 9 determines that the mobile station 2a does not exist in the radio communication radio wave zone 7. Is determined to return to step S1, and the same operation is repeated. Therefore, in this case, the base stations 4 and 5 do not communicate with the mobile station 2a.

Next, a second communication control example using the above-described optical reflection path characteristic will be described with reference to the flowchart shown in FIG.
First, polling signals (question radio waves) are transmitted from the base stations 4 and 5 (step S11). Next, the determination unit 8 determines whether each of the base stations 4 and 5 has received a response radio wave from the mobile station based on the reception results of the base stations 4 and 5 (step S12).

  As a result of the determination, when each of the base stations 4 and 5 can receive the response radio wave from the mobile station 2, the determination unit 8 further determines the reception power of each response radio wave in each of the base stations 4 and 5 in advance. It is determined whether or not the predetermined value has been reached, for example, whether or not the received power of each response radio wave at each of the base stations 4 and 5 has reached the same predetermined value (step S13).

  As a result of this determination, when the received power of each response radio wave in each of the base stations 4 and 5 has reached the same value, the control unit 9 is the mobile station 2 in the radio communication radio wave area 7. If it is determined that there is, the base stations 4 and 5 are controlled to start communication with the mobile station 2 (step S14).

  As a result of the determination in step S12, when each of the base stations 4 and 5 cannot receive the response radio wave from the mobile station 2, or as a result of the determination in step S13, If the received power does not reach the same value, the control unit 9 determines that the mobile station is a mobile station 2a that does not exist in the radio communication radio wave range 7, returns to step S11, and repeats the same operation as described above. Therefore, in this case, the base stations 4 and 5 do not communicate with the mobile station 2a.

  In this manner, a plurality of (for example, two) base stations are arranged so as to form overlapping radio communication radio spheres by forming the same radio wave irradiation area at a certain distance. Depending on whether or not the response radio waves from the mobile station can be received by all of the plurality of base stations, the response radio wave from the mobile station within the radio communication radio wave range or the response radio wave from other than that is judged to continue or abort the communication. Is to do.

  In this way, by using only the optical reflection path characteristics of radio waves, time management between mobile stations and precise base stations for measuring the phase difference of received radio waves as in the past, precise clock pulses Or, it is not necessary to perform distance measurement using radio waves with higher frequencies as communication radio waves, and it is detected whether it is a reflected radio wave from a mobile body with a relatively simple configuration, and other than the radio communication radio wave range to be communicated Therefore, it is possible to prevent unnecessary communication with a mobile station that should not communicate with the mobile station.

  In the above embodiment, the case where two base stations are installed has been described. However, the present invention is not limited to this, and the present invention can be similarly implemented even if two or more base stations are installed.

The schematic diagram which shows schematically the structure of the ETC system as a radio | wireless communications system which concerns on embodiment of this invention. The schematic diagram explaining the case where a mobile station exists in the radio | wireless communication radio wave range. The schematic diagram explaining the electromagnetic wave path | route by the optical reflection path | route characteristic. The flowchart explaining the flow of the 1st communication control example using an optical reflection path characteristic. The flowchart explaining the flow of the 2nd communication control example using an optical reflection path characteristic.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vehicle (mobile body), 2 ... Mobile station, 3 ... Traveling path (moving path), 4, 5 ... Base station, 4a, 5a ... Antenna, 6a, 6b ... Radio wave irradiation area, 7 ... Radio communication radio wave area, 8: Determination unit (determination unit), 9: Control unit (control unit), 10: Response radio wave, 11: Interrogation radio wave.

Claims (2)

A plurality of base stations arranged so as to form overlapping radio communication radio spheres by forming the same radio wave irradiation area for a predetermined position of a moving path on which the moving body moves;
A mobile station that is mounted on the mobile body and starts communication with the base station by transmitting a response radio wave to the interrogation radio wave from the base station when entering the radio communication radio wave range; and
Determination means for determining whether or not response radio waves from the mobile station have been received in all of the plurality of base stations;
As a result of the determination by the determination means, when the response radio wave from the mobile station can be received in all of the plurality of base stations, the mobile station is determined to be a mobile station existing within the radio communication radio wave range, and thereafter If the response radio wave from the mobile station is not received in all of the plurality of base stations, the mobile station determines that the mobile station is not in the radio communication radio wave range and thereafter Control means for controlling so as not to perform communication;
A wireless communication system comprising: A plurality of base stations arranged so as to form overlapping radio communication radio spheres by forming the same radio wave irradiation area for a predetermined position of a moving path on which the moving body moves;
A mobile station that is mounted on the mobile body and starts communication with the base station by transmitting a response radio wave to the interrogation radio wave from the base station when entering the radio communication radio wave range; and
First determination means for determining whether or not response radio waves from the mobile station have been received in all of the plurality of base stations;
As a result of the determination by the first determination means, when the response radio waves from the mobile station can be received in all of the plurality of base stations, the reception power of each response radio wave in all of the plurality of base stations is determined in advance. Second determination means for determining whether or not the predetermined value has been reached;
If the reception power of each response radio wave in all of the plurality of base stations has reached a predetermined value as a result of the determination by the second determination means, the mobile station is a mobile station that exists within the radio communication radio wave range. If the result of determination by the first determination means is that the response radio wave from the mobile station could not be received in all of the plurality of base stations, or the second If the reception power of each response radio wave in all of the plurality of base stations does not reach a predetermined value as a result of the determination by the determination means, it is determined that the mobile station is a mobile station that does not exist within the radio communication radio wave range. Control means for controlling not to perform subsequent communication;
A wireless communication system comprising:

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