JPH04230131A - Mobile object communication system - Google Patents

Abstract

PURPOSE:To prevent the reduction of a reception electric field of a mobile object even at a bent position of an LCX by detecting the running position of the mobile object and varying the directivity of a mobile station antenna in response to the detection. CONSTITUTION:The mobile object 3 receives a radio wave from an LCX 1 while directing the beam direction of a mobile station antenna 4 at the angle of theta1 for blocks A, D in which the LCX 1 is spanned straightly. When the mobile object 3 enters blocks B, C in which the LCX 1 is bent by an obstacle 2, position information detected by a position detection ground set 8 is received by the directivity switching device 7 of the mobile station antenna 4 in the mobile object 3. The directivity switching device 7 of the mobile station antenna 4 receiving the position information switches the beam direction of the mobile station antenna 4 to an angle theta2 for the block B and to an angle theta3 for the block C in response to the position information. Thus, a reception electric field with less reduction and fluctuation is obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system for communicating between a base station and a moving object such as a train.

0002

2. Description of the Related Art FIG. 3 shows, for example, an LCX communication system, 1
This is a configuration diagram showing an overview of a conventional mobile communication system described on pages 9 to 55 (co-authored by Toshihiko Kishimoto and Shin Sasaki, published by the Institute of Electronics and Communication Engineers on August 20, 1980), in which 1 is a transmitting means. Leaky coaxial cable (hereinafter referred to as LC)
2 is an obstacle such as an electric pole, 3 is a moving object such as a train, 4 is a mobile station antenna, 5 is a mobile station radio device, 6 is a track, and 10 is a base station connected to LCX1. .

Next, the operation will be explained. The radio waves transmitted from the base station 10 enter the LCX1, and by passing through the LCX1, the radio waves reach the mobile object 3 at an angle of θ1 shown in FIG.
radiated towards. Mobile station antenna 4 in mobile unit 3
The beam is received at an angle θ1 as shown in the figure and guided to the mobile station radio equipment 5. When LCX1 is stretched straight, the radiation angle is constant at θ1, but LC
When X1 is bent as shown in the figure to avoid obstacle 2, the radiation angle changes as θ2 and θ3 in the figure. Since the moving body 3 itself does not know the bending point of this LCX1,
Conventionally, the beam of the mobile station antenna 4 had to travel with the beam fixed at θ1.

0004

[Problems to be Solved by the Invention] Since the conventional mobile communication system using the LCX1 is configured as described above, when the LCX1 is bent, the radiation angle changes, but the beam of the mobile station antenna 4 is Since the movable body 3 travels in a fixed manner, the angles do not match, which causes a problem in that the electric field received by the movable body 3 drops.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a mobile communication system in which the received electric field of a mobile body does not drop even if the LCX is bent.

[0006]

[Means for Solving the Problems] A mobile communication system according to the present invention detects the traveling position of a mobile body and changes the directivity of a mobile station antenna according to this detection, thereby detecting a bending point of an LCX. The present invention is also designed to prevent a drop in the received electric field of a moving body.

[0007]

[Operation] The mobile communication system according to the present invention obtains a receiving electric field of a mobile body with little fluctuation by traveling while adjusting the beam of the mobile station antenna to the radiation angle of the bent LCX.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, parts corresponding to those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

7 is a directivity switching device for the mobile station antenna 4;
Reference numeral 8 designates position detection ground elements installed at a plurality of predetermined locations within the track 6 as position detection means.

Next, the operation will be explained. Radio waves transmitted from the base station 10 enter the LCX1, and the radiation angle is θ1 in sections A and D where the LCX1 is straight, and the radiation angle is θ1 in the section B where the LCX1 is bent by an obstacle 2 such as a utility pole. θ2, and in the section of C that is also bent, the radiation angle θ
3 and are respectively radiated toward the moving body 3. In sections A and D, the mobile unit 3 receives radio waves from the LCX 1 by directing the beam direction of the mobile station antenna 4 to the angle θ1 as in the conventional case. When a moving object 3 such as a train enters sections B and C, the directivity switching device 7 of the mobile station antenna 4 in the moving object 3 receives the position information detected by the position detecting ground element 8. The directivity switching device 7 of the mobile station antenna 4 that has received the position information switches the beam direction of the mobile station antenna 4 to θ2 in the B section and to θ3 in the C section according to the position information. As a result, a received electric field with less drop and fluctuation can be obtained.

Generally, a railway is a one-dimensional moving body with a fixed running route, and the directivity switching device 7 of the mobile station antenna 4
The effects of the invention described above can be obtained by storing the beam direction of the mobile station antenna 4 corresponding to the position information.

[0012] In the above embodiment, a method for detecting the position of the moving body 3 using a position detecting ground element has been described, but it is also possible to use a method of counting the number of rotations of wheels of a train or the like, or a method of counting the number of periodically existing structures. Other methods such as Also,
In the above embodiment, a mobile communication system using the LCX1 has been described, but even in the case of a general space wave mobile communication system as shown in FIG. 2, the same effects as in the above embodiment can be achieved.

In FIG. 2, a signal from the base station 10 is radiated from a spatial wave antenna 9 serving as a transmitting means. As the mobile object 3 travels on the track 6, the position is detected by the directivity switching device 7 of the mobile station antenna 4 and the position detecting ground element 8, and the mobile station antenna 4
By switching the beam directions as θ4, θ5, and θ6, a received electric field with less drop and fluctuation is obtained.

[0014]

[Effects of the Invention] As described above, according to the present invention, the position of a mobile object is detected and the directivity of the mobile station antenna is made variable according to the position information. It is possible to obtain a received electric field with less drop and fluctuation than in the case of the conventional method, and as a result, it is possible to achieve effects such as being able to realize a high quality wireless line.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a mobile communication system according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a mobile communication system according to another embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional mobile communication system.

[Explanation of symbols]

1 Leaky coaxial cable 3. Mobile object 4 Mobile station antenna 6 Railway track 7 Directivity switching device 8 Ground element for position detection 9 Space wave antenna 10 Base station In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A mobile communication system in which a mobile station antenna provided on a mobile body traveling on a certain route receives a signal transmitted from a base station as a spatial wave signal via a transmitting means, comprising: A mobile communication system comprising: a position detection means for detecting the position of the mobile body on the travel route; and a directivity switching device for switching the directivity of the mobile station antenna according to the position information of the position detection means.