Antenna and antenna operation method for a cellular radio communications system

A cell site for a sectored cell of a cellular radio communications system, comprising;

• a plurality of base transceiver stations (BTSs), each for handling radio communications with subscriber units in a respective corresponding sector or group of sectors of said cell;
• a principal-beam antenna coupled to each BTS;
• and
• a downward-looking antenna (DLA) coupled to a first one of said plurality of BTSs, being said BTS for handling communications in a corresponding first sector or group of sectors of said cell via a first of said principal-beam antennas;
• in which said first principal-beam antenna generates a first principal beam covering said first sector or group of sectors;
• in which one or more of said principal-beam antennas, other than said first principal-beam antenna, generates a principal beam having a sidelobe or backlobe which has a beam gain and falls within said first sector or group of sectors below a predetermined angle of elevation;
• and
• in which said DLA generates a DLA beam having coverage in azimuth corresponding to said first sector or group of sectors, coverage in elevation below said predetermined angle of elevation and a beam gain greater than said beam gain of said sidelobe or backlobe, and operates to enable power control of radio transmissions from subscriber units communicating via said first principal beam and positioned within said DLA beam.

An antenna unit for a sectored cell of a cellular radio communications system comprising, fabricated as parts of a single antenna unit;

• a ground plane;
• a principal-beam antenna mounted at a first portion of said ground plane;
• and
• a downward-looking antenna (DLA) mounted at a second portion of said ground plane;
• such that, in use, said principal-beam antenna generates a principal beam, or a set of principal beams, having a predetermined coverage area and said DLA generates a DLA beam having a coverage in elevation overlapping a low elevation portion of said predetermined coverage area of said principal beam or set of principal beams.

A method for operating a sectored cell of a cellular radio communications system comprising;

• providing first and second base transceiver stations (BTSs) respectively coupled to first and second principal-beam antennas for generating first and second principal beams for communicating with subscriber units in corresponding first and second sectors of said cell, said first principal beam having a predetermined coverage area and said second principal beam having a sidelobe or backlobe which has a beam gain and falls within said first sector in a low elevation portion of said predetermined coverage area;
• providing a downward-looking antenna (DLA) coupled to said first BTS for generating a DLA beam having coverage in azimuth corresponding to said first sector, coverage in elevation in said low elevation portion of said predetermined coverage area of said first principal beam, and beam gain greater than that of said sidelobe or backlobe;
• and,
• operating said first BTS coupled to said DLA in order to control the power of transmissions from a subscriber unit in said first sector within said coverage of said subscriber unit, in order to reduce interference caused by said transmissions received by said second BTS via said sidelobe or backlobe.

An antenna for a sectored cell of a cellular radio communications system, being a third antenna of said cell, in which said cell has a cell site comprising;

• a first antenna for generating a first principal beam for radio communication to and/or from subscriber units located in a first sector of said cell;
• and
• a second antenna for generating a second principal beam for radio communication to and/or from subscriber units located in a second sector of said cell, said second principal beam having a sidelobe or backlobe which has a beam gain and falls within said first sector below a predetermined angle of elevation;
• in which said third antenna is a downward-looking antenna (DLA) located at said cell site, for generating a DLA beam having coverage in azimuth corresponding to said first sector, coverage in elevation substantially below said predetermined angle of elevation, and a beam gain greater than said beam gain of said sidelobe or backlobe;
• in which said DLA generates only an uplink beam, for receiving radio transmissions from subscriber units.

An antenna for a sectored cell of a cellular radio communications system, being a third antenna of said cell, in which said cell has a cell site comprising;

• a first antenna for generating a first principal beam for radio communication to and/or from subscriber units located in a first sector of said cell;
• and
• a second antenna for generating a second principal beam for radio communication to and/or from subscriber units located in a second sector of said cell, said second principal beam having a sidelobe or backlobe which has a beam gain and falls within said first sector below a predetermined angle of elevation;
• in which said third antenna is a downward-looking antenna (DLA) located at said cell site, for generating a DLA beam having coverage in azimuth corresponding to said first sector, coverage in elevation substantially below said predetermined angle of elevation, and a beam gain greater than said beam gain of said sidelobe or backlobe;
• in which said DLA transmits noise at a predetermined power for use by a subscriber unit for open-loop power control.

An antenna for a sectored cell of a cellular radio communications system, being a third antenna of said cell, in which said cell has a cell site comprising;

• a first antenna for generating a first principal beam for radio communication to and/or from subscriber units located in a first sector of said cell;
• and
• a second antenna for generating a second principal beam for radio communication to and/or from subscriber units located in a second sector of said cell, said second principal beam having a sidelobe or backlobe which has a beam gain and falls within said first sector below a predetermined angle of elevation;
• in which said third antenna is a downward-looking antenna (DLA) located at said cell site, for generating a DLA beam having coverage in azimuth corresponding to said first sector, coverage in elevation substantially below said predetermined angle of elevation, and a beam gain greater than said beam gain of said sidelobe or backlobe;
• in which said DLA and said first antenna are fabricated as parts of a single antenna unit.

A method for operating a sectored cell of a cellular radio communications system comprising;

• providing first and second base transceiver stations (BTSs) respectively coupled to first and second principal-beam antennas for generating first and second principal beams for communicating with subscriber units in corresponding first and second sectors of said cell, said first principal beam having a predetermined coverage area and said second principal beam having a sidelobe or backlobe which has a beam gain and falls within said first sector in a low elevation portion of said predetermined coverage area;
• providing a downward-looking antenna (DLA) coupled to said first BTS for generating a DLA beam having coverage in azimuth corresponding to said first sector, coverage in elevation in said low elevation portion of said predetermined coverage area of said first principal beam, and beam gain greater than that of said sidelobe or backlobe, said first BTS communicating with said subscriber units only on the uplink, downlink communications being carried via said first principal beam;
• and,
• operating said first BTS coupled to said DLA in order to control the power of transmissions from a subscriber unit in said first sector within said coverage of said subscriber unit, in order to reduce interference caused by said transmissions received by said second BTS via said sidelobe or backlobe.