System. method, and base station antenna for cellular radio coverage
View Patent ↗A system, method, and base station antenna for improved coverage in a cellular mobile telephony network. Each cell in the network has an area defined by azimuth and range limits. In the system, a first cell and a second cell are essentially adjacent to each other in azimuth. A third cell has an azimuth limit that is essentially equal to the total azimuths of the first and second cells, and has a range coverage that is shorter than the ranges of the first or second cells. The base station antenna forms separate “conventional” beams for the first and second cells, and forms a “near cell” beam for the third cell.
1. A method in a radio base station for providing mobile telephony coverage to a service area, said method comprising the steps of:
transmitting and receiving radio signals from the base station into a first cell and a second cell, wherein the first cell covers a first azimuth interval and the second cell covers a second azimuth interval adjacent to the first azimuth interval, and the first and second cells cover a first range interval between a minimum range and a maximum range from the base station;
transmitting and receiving radio signals from the base station into a third cell covering a second range interval having a maximum range essentially equal to the minimum range of the first range interval, said third cell covering a third azimuth interval essentially equal to the total azimuth interval of the first and second cells; and
providing telephony services through the third cell to all traffic within the third azimuth interval and within the second range interval.
2. A system for cellular mobile telephony, the system comprising:
a base station antenna for transmitting and receiving radio signals in a plurality of radiation patterns; and
a plurality of cells formed by the radiation patterns, each cell having a specific area coverage defined by an azimuth interval coverage (α 1 , α 2 ) and a range coverage between a minimum and a maximum range (R 0 , R′), wherein:
a first and a second cell cover first and second areas, respectively, said areas being defined by first and second azimuth intervals and first and second range intervals, respectively, the first and second cells being essentially adjacent to each other in azimuth; and
a third cell covers a third area defined by a third azimuth interval and a third range interval, wherein the third azimuth interval is essentially the same as, and coinciding with, the total azimuth interval of the first and the second cells, but with the third cell having a range coverage which is significantly smaller than the first or second range intervals; and
means for handling all traffic within the third area by the third cell.
3. The system as recited in claim 2 , wherein the range intervals of the first and second cells are essentially equal.
4. The system of any as recited in claim 2 , wherein each of the first, second, and third cell coverage areas are essentially the same size.
5. The system as recited in claim 2 , wherein the first and second cells together have an azimuth interval coverage of 360 degrees.
6. The system as recited in claim 2 , wherein the maximum range (R′) of the third range interval is one-half of the minimum range (Ro) of the first and second range intervals.
7. An array antenna for use in a base station in a mobile telephony system, comprising:
a first plurality of radiation elements for generating radiation patterns which cover first and second areas, respectively, said areas being defined by first and second azimuth intervals and first and second range intervals, respectively, the first and second cells being essentially adjacent to each other in azimuth;
a second plurality of radiation elements for generating a radiation pattern which covers a third area defined by a third azimuth interval and a third range interval, wherein the third azimuth interval is essentially the same as, and coinciding with, the total azimuth interval of the first and the second areas, but with the third area having a range coverage which is significantly smaller than the first or second range intervals;
wherein the array antenna is a cylindrical array antenna in which' said first plurality of radiation elements include a number of antenna elements arranged in a first set of columns around a circumference of the cylindrical antenna; and
wherein the second plurality of radiation elements is arranged in a second set of columns arranged around the circumference of the cylindrical antenna, each column in the second set including at least one radiation element.
8. The antenna as recited in claim 7 , wherein at least one of the columns in the second set includes at least two radiation elements.
9. The antenna as recited in claim 8 , wherein each set of antenna elements in each column is arranged to be fed with separate vertical phase-matched feed networks.
10. The antenna as recited in claim 7 , wherein the second plurality of radiation elements includes antenna, elements which are mechanically tilted so as to achieve a radiation pattern which decreases their coverage in the first and second areas.
11. The antenna as recited in claim 7 , wherein the second plurality of radiation elements is fed via a common feed network.
12. The antenna as recited in claim 7 , wherein both the first and the second pluralities of radiation elements are connected to a two-dimensional beam forming network, which forms a plurality of radiation patterns in both azimuth and elevation, so that separate patterns may be formed for each of the first, second, and third areas in the cellular telephony system.