JPH0556695B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Purpose of the Invention (Field of Industrial Application) The present invention is applicable to a relatively wide range of applications, as seen in wireless communication systems, particularly land mobile wireless communication systems and land subscriber wireless communication systems. When a large number of child radio stations distributed within a range communicate with a parent radio station (base station),
The present invention relates to a wireless communication system in which an antenna with a large gain can be used as a base station antenna without increasing the number of base station antennas, or in which the antenna gain can be increased when the number of base station antennas is the same.

(Prior art) Conventional radio communication systems such as land mobile radio communication systems and land subscriber radio communication systems are schematically illustrated in the fifth example.
As shown in the figure. In such a system, child radio station 2
is distributed over a relatively wide range. Since the parent radio station (base station) 1 communicates with a large number of child radio stations 2 in this way, the base station antenna 3 has a beam that covers a wide angular range (hereinafter described as all directions in the horizontal plane). There is a need.

FIG. 6 schematically shows the horizontal directivity of the antenna 3 of the base station 1 conventionally used in such a system. Since the beam 4a covers all directions in the horizontal plane, it is possible to use an omnidirectional antenna 3a in the horizontal plane as shown in FIG.
As shown in FIG. b, the horizontal plane may be divided into several angular ranges (for example, 90° each; hereinafter referred to as zones), and one antenna 3b may be arranged so that the beam 4b covers each zone. In reality, it is not possible to obtain ideal fan-shaped directivity, so adjacent parts interfere, so the frequency or polarization method is changed. That is, if the number of antennas 3b of the base station 1 is N, the system configuration is such that one antenna handles 360°/N zones.

Compared to the omnidirectional antenna 3a in the horizontal plane as shown in Fig. 6a, the antenna 3b with the 90° beam 4b as shown in Fig. 6b has a higher antenna gain (directivity gain).
is large. From the perspective of line design for a wireless communication system, the larger the antenna gain, the easier the line design, which makes it possible to enlarge the service area (transmission distance) and increase the amount of information transmitted. Therefore, antenna 3 of base station 1
It is also preferable to use an antenna with a larger gain, but for this purpose it is necessary to create a configuration in which the zones are divided into even smaller zones as shown in FIG. 6c. Further, by dividing the zones into smaller sections, it is possible to configure a system in which the same frequency is used simultaneously in different zones, which is preferable in terms of effective use of frequencies and increase in transmission capacity. However, in order to divide the zones finely in this way, there is a problem in that a large number of antennas 3c of the base station 1 with narrow beam 4c widths are required, and if there are many antennas, installation space and maintenance/inspection time are required. . Therefore, from the viewpoint of economic efficiency, it has not been possible to design the zone size of a wireless communication system such as a land mobile wireless communication system or a land subscriber wireless communication system to be relatively narrow.

(Problems to be Solved by the Invention) The present invention solves the problem of conventional wireless communication systems in which the number of base station antennas increases when fine zoning is performed, without increasing the number of base station antennas. The aim is to subdivide zones and provide a more efficient wireless communication system.

(2) Structure of the invention (means for solving problems) In a wireless communication system in which a master radio station installed on the ground and a plurality of slave radio stations communicate with each other, the antenna of the master radio station is placed on a horizontal plane. Either a fixed single annular antenna equipped with a plurality of feeding horn groups that radiates multiple beams simultaneously and suitably densely in all directions without omission, or the antenna of the parent radio station can radiate multiple beams simultaneously and appropriately densely in all directions; One or more antenna beams are evenly scanned back and forth in a horizontal plane by one or more feeding horns that face a single reflecting mirror installed in each zone divided into multiple directions and rotate back and forth continuously or in a switching manner. At the same time, one or more child radio stations in the direction of the beam communicate with the parent radio station in synchronization with the reciprocal scanning of the beam.

(Example 1) A first example of the present invention will be described with reference to FIGS. 1 and 2.

When explaining the present invention, a wireless communication system similar to that shown in FIG. 5 will be considered. First, consider dividing the horizontal plane into N zones α as shown in Figure 1a (in Figure 1a, N = 4, 90° zones α). Furthermore, one zone α is divided into M smaller subzones β as shown in FIG. 1b. If the zone α is subdivided in this way in the conventional wireless communication system, antennas 3 of N×M base stations 1 are required. In the wireless communication system according to the present invention, as shown in FIG. 1c, a multi-beam antenna capable of radiating M beams 4 is used as the antenna 3 of the base station 1.

In order to realize the wireless communication system according to the present invention, a plurality of beams 4 as shown in FIG.
An antenna 3 is required that can simultaneously radiate both. A torus antenna will be described as a specific example of this type of antenna.

As shown in FIG. 2, consider a reflector antenna consisting of a single reflector 5 and a plurality of feeding horns 6. The curve 7 in the longitudinal section (y-z plane) of the reflecting mirror 5 is a parabola or a similar curve having a focal point at the position of the feeding horn 6. The curved surface trajectory of the reflecting mirror 5 is defined as the curved surface locus created when the vertical section curve 7 is rotated around the y-axis as the center of rotation. That is, the cross-sectional curve 8
is shaped like an arc. The feeding horn 6' is arranged at a position and in a direction where the feeding horn 6 is rotated about the y-axis, and the radio waves radiated from the feeding horn 6' radiate a beam 4' in the z'-axis direction. Since the cross-sectional curve 7' shown by the dotted line is equal to the curve 7, the radiation beam 4 from the feeding horn 6 and the radiation beam 4' from the feeding horn 6' have the same shape and the main radiation directions are the z direction and the z' direction. It will be different. By arranging a plurality of feeding horns 6 on concentric arcs around the y-axis as shown in FIG. 2b and exciting each one, a multi-beam antenna can be obtained which can simultaneously radiate a plurality of beams 4 in the horizontal direction.

The beam width in the horizontal plane of this antenna is
and changes depending on the positional relationship between the rotation axis y and the power feeding horn 6. If the distance between the reflector 5 and the y-axis is R, and the distance between the feeding horn 6 and the y-axis is r (see Figure 2 a), the beam width in the horizontal plane becomes narrowest around r/R=0.5 (gain (becomes large), such parameters have traditionally been selected for torus antennas for satellite communication earth station antennas.

In order to realize the wireless communication system according to the present invention, it is necessary to cover the zone α in the horizontal plane densely with a plurality of beams 4 as shown in FIG. 1c. Therefore, in FIG. 2, the radiation beams 4 of adjacent horns 6 overlap each other in the horizontal plane (for example -
(beams must be adjacent at 3 dB). In other words,
It is not limited by the physical size of the feeding horn 6, and it is necessary to set the width of the beam 4 in the horizontal plane to a predetermined value (360°/N/M). For this purpose, when using an antenna as shown in FIG. 2b as the antenna 3 of the base station 1 to realize the wireless communication system according to the present invention, the parameter r/R is selected approximately as shown in the following equation. There is a need.

r/R=1/2 (1±H ₂ /H ₁ )...(1) Here, H ₁ is the width of the beam 4 of the feeding horn 6, H ₂
is the beam 4 width in a predetermined horizontal plane.

(Function 1) The present invention changes the parameters of the multi-beam antenna described above and radiates a plurality of beams simultaneously through a plurality of feeding horns densely and without leakage, thereby forming an N×M subzone β structure. This can be handled by the antennas 3 of N base stations 1. Therefore, the number of base stations can be reduced to 1/M compared to the conventional one, and if the base stations are configured with N×M base stations, the antenna gain will increase. Also, compared to a conventional system using the antennas 3 of N base stations 1, the beam of the antenna 3 of the base station 1 becomes finer and the gain becomes larger, so it is possible to increase the maximum service distance or The antenna 9 can be made smaller. In addition, subzone 3
For example, as shown in FIG. 1b, the same frequencies ₁ to ₃ can be reused to increase the total transmission capacity.

(Example 2) When explaining the present invention, consider M subzones β which are subdivided as shown in FIG. 1b. If zone α is subdivided in this way using conventional wireless communication methods,
Antennas 3 of N×M base stations 1 were required. In the wireless communication system according to the invention, the radiation beam 4 irradiating one subzone β of FIG.
The base station 1 is equipped with a beam-shifting antenna that performs reciprocating scanning by continuously or sequentially switching over a plurality of feeding horns without rotating the antenna body within the zone β.
It is used as antenna 3 of The base station antenna 3 emits a beam 4 corresponding to the size of the subzone β, changes the direction of the beam 4 within the zone α over time, and communicates with the child radio station 2 in the emitted subzone β. Let's do it. In other words, the M subzones β are time-divisionally accessed.
In this case, it is of course possible for a plurality of child radio stations 2 to exist within one subzone β and to perform multiple access.

In order to realize the wireless communication system according to the present invention, a beam-shifting antenna capable of scanning four beams within the zone α is required. As a specific example of this type of antenna, a case will be described in which the torus antenna described in FIG. 3 is used.

The reflector antenna 5 in FIG. 3 has the same reflector as the reflector 5 in FIG. The power supply horn 6 is
It is attached to a moving mount 10. The movable mount 10 is a mechanism that reciprocates at a constant speed along an arcuate parallel rail 11 as the screw rod 13 of the reversible drive motor 12 rotates, thereby rotationally moving the power supply horn 6 around the y-axis. As already explained, the reflecting mirror 5 is rotationally symmetrical around the y-axis, so when the feeding horn 6 is rotated around the y-axis, the radiation beam 4 changes its direction around the y-axis while maintaining its beam shape. It turns out. That is, instead of arranging a plurality of horns 6 and radiating a plurality of beams 4 simultaneously as shown in FIG. 3, the beams 4 can be scanned in a horizontal plane by moving the horns 6. In synchronization with the movement of the movable mount 10, transmission and reception are performed with slave radio stations 2 included in the four beam directions.

Although the reflector antenna 3 shown in FIG. 3 is a mechanical beam scanning antenna, an example of an electrical beam scanning antenna is shown in FIG. The reflector antenna 3 in FIG. 4 has the same reflector as the reflector 5 in FIG. 2b, and as in the case of FIG. placed above.
The horns 6 are arranged such that the radiation beams 4 of adjacent horns 6 closely overlap each other in the horizontal plane, so that a plurality of beams 4 completely cover a zone in the horizontal plane. These power supply horns 6 are connected to a transmitter/receiver device 15 via a power switch 14 . Horn 6 excited by this power switch 14
By switching sequentially, the four beam directions can be switched and four beams can be scanned in a horizontal plane. In synchronization with the operation of the power switch 14, transmission and reception are performed with the slave radio stations 2 included in the four beam directions.

(Function 2) With the above-described configuration, the present invention can support a zone α configuration subdivided into N×M pieces using the antennas 3 of N base stations 1. Compared to a conventional system using the antennas 3 of N base stations 1, the beam 4 of the antenna 3 of the base station 1 becomes narrower and the gain becomes larger, so the maximum service distance can be made longer and the The antenna can be made smaller. In addition, it is possible to flexibly respond to cases where the amount of information transmission required for each subzone β differs or changes over time, thereby substantially increasing the total transmission capacity. You can also do it. Furthermore, since the antenna is small and the feeding horns are switched and moved quickly without moving the antenna itself, the entire antenna is lightweight and can perform high-speed scanning.

(3) Effects of the Invention As explained above, in the wireless communication system according to the present invention, when multiple beams are transmitted simultaneously using multiple power feeding horns without leakage, a single unit can be used for reciprocating rotation drive by switching continuously or sequentially. In the case of radiation scanning, N base station antennas are sufficient to obtain the same antenna gain as in the conventional N×M basis, and the number of base station antennas can be smaller than the number of wireless zones. The antenna gain increases. It is possible to further subdivide a wireless zone and use a base station antenna with a large gain, so the maximum service distance can be made longer, the antenna of a child wireless station can be made smaller, or the same frequency can be used between subzones. It has excellent effects such as increasing the total transmission capacity by reusing it and making it possible to establish a more efficient wireless communication system.

[Brief explanation of drawings]

Figures 1a, b, and c are diagrams for explaining the basic principle of a base station antenna used in the wireless communication system according to the present invention, and Figures 2a and b are used in the first embodiment of the wireless communication system according to the present invention. A conceptual diagram of the base station antenna. Figures 3 and 4 are conceptual diagrams of the base station antenna used in the same and second embodiments. Figure 5 is a conceptual diagram of the base station antenna used in the same and second embodiments. Figure 5 is a conceptual diagram of the base station antenna. FIG. 6, which is a diagram for explaining the system, is a schematic diagram for explaining beam coverage in a horizontal plane of a base station antenna according to a conventional system. 1... Parent radio station (base station), 2... Child radio station,
3...Base station antenna, 4, 4', 4a to 4c...
... Beam, 5 ... Reflector, 6, 6' ... Feeding horn, 7, 7' ... Vertical section curve, 8 ... Cross section curve (circular arc), 9 ... Child radio station antenna, 10 ... Movement Mount, 14...Power switch. α……Zone,
β...Subzone.

Claims (1)

[Scope of Claims] 1. In a wireless communication system in which a master radio station installed on the ground and a plurality of slave radio stations communicate with each other, the antenna of the master radio station is installed in a plurality of antennas in all directions in a horizontal plane. A wireless communication system characterized by the use of a fixed reflector antenna equipped with multiple feeding points that simultaneously and densely radiates beams. 2. In a wireless communication system in which a master radio station installed on the ground and a plurality of slave radio stations communicate with each other, the antenna of the master radio station uses a reflector installed in each zone that divides a horizontal plane in all directions. One or more antenna beams are evenly scanned back and forth in a horizontal plane using one or more feeding points, and in synchronization with the scanning of the beam, one or more child radio stations in the direction of the beam are A wireless communication method characterized by communicating with a wireless station.