Mobile radio communication system with repeater station grid

• US 4,727,590 A
• Filed: 07/06/1987
• Issued: 02/23/1988
• Est. Priority Date: 09/05/1986
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Mihashi, Kohji, Kawano, Minori
• Primary Examiner(s): Lev, Robert
• Application Number:
  US07/069,786
• Time in Patent Office: 232 Days
• Field of Search: 455/17, 455/34, 455/33, 379/59, 379/60, 379/63
• US Class Current: 455/446
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04W 16/26 Cell enhancers or enhancement, e.g. for tunnels, building shadow

Abstract

A mobile radio communication system has base stations 1a, 1b, 1c at the centers of major service areas A, B, C defined by a contiguous array of hexagons or partially overlapping circles, and repeater or one way relay stations 3a-3m at each vertex or intersection point. The repeater stations have directional receiving antennas subtending successive 120° arcs of surrounding minor service areas similarly defined by a ring array of hexagons or circles, amplifiers for imparting a high gain to signals received from mobile units in the minor service areas, and narrow width transmitting antennas for relaying the amplified signals to the base station closest each mobile unit. Such an arrangement enables a substantial reduction in the transmitter output capacity of the mobile units.

Claims

1. A mobile radio communication system, comprising:

(a) a plurality of geographical, mutually adjacent major service areas (A, B, C) defined by at least three partially overlapping circles oriented such that their centers are individually disposed at vertices of a triangle,

(b) a plurality of base stations (1a, 1b, 1c) each having transmitting and receiving antennas individually and centrally disposed in the major service areas,

(c) a mobile unit (2) including transmitter and receiver means, and

(d) a plurality of repeater stations (3a-3m) individually disposed surrounding each base station and at points of intersection of said circles, each repeater station lying at the approximate center of a surrounding, circular, minor service area and including first antenna means for receiving a signal transmitted from a mobile unit in said minor service area, means for amplifying said signal, and second antenna means for transmitting said amplified signal to a base station nearest the mobile unit.

2. A system according to claim 1, wherein:

(a) the circles defining the major service areas are of equal diameter and intersect at a common point, and

(b) the triangle is an equilateral triangle.

3. A system according to claim 1, wherein the circles defining the minor service areas are of equal diameter and partially overlap to define (a) a ring of circles surrounding each major service area, and (b) a remaining circle surrounding each base station of equal diameter to the minor service area circles such that the range of said mobile unit transmitter may be limited to the radius of said minor service area circles.

4. A system according to claim 2, wherein the circles defining the minor service areas are of equal diameter and partially overlap to define (a) a ring of circles surrounding each major service area, and (b) a remaining circle surrounding each base station of equal diameter to the minor service area circles such that the range of said mobile unit transmitter may be limited to the radius of said minor service area circles.

5. A system according to claim 4, wherein:

(a) each first antenna means comprises three antennas each having a directivity of 120°

oriented to embrace contiguous 120°

sectors (40, 41,

     42) of a circle and having central axes individually aligned with associated base stations, and

(b) each second antenna means comprises three narrow directivity antennas individually oriented towards associated base stations.

6. A system according to claim 5, wherein the first and second antenna means are sufficiently spaced apart on a vertical mounting tower to avoid interference between transmitted and received signals.

7. A system according to claim 6, wherein the transmitting and receiving antennas at each base station are omnidirectional.

8. A system according to claim 4, wherein:

(a) each first antenna means comprises six antennas each having a directivity of 60°

oriented to embrace contiguous 60°

sectors (43-48) of a circle, and

(b) each second antenna means comprises three narrow directivity antennas individually oriented towards associated base stations.

9. A system according to claim 4, wherein the area of each remaining circle surrounding a base station is approximately one-third the area of the circles defining the major service areas.

10. A mobile radio communication, comprising:

(a) a base station (1a) having transmitting and receiving antennas, said base station being disposed in the center of a major geographical service area (A),

(b) a mobile unit (2) including transmitter and receiver means, and

(c) a plurality of spaced repeater stations (3a-3f) disposed surrounding said base station and individually centrally disposed in associated minor service areas, each repeater station including first antenna means for receiving a signal transmitted from a mobile unit in an associated minor service area, means for amplifying said signal and second antenna means for transmitting said amplified signal to said base station.

11. A system according to claim 11, wherein:

said repeater stations are disposed equally spaced from one another along and around an outer boundary of said major service area corresponding to a maximum transmitting range of said base station.