This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7 119 arising from an application entitled, METHOD FOR CALCULTING THE COVERAGED AREA ACCORDING TO THE ANTENNA PATTERNS IN A SECTOR BASE STATION, earlier filed in the Korean Industrial Property Office on Sep. 8, 1998, and there duly assigned Serial No. 1998-36978.
The present invention relates to a method for providing the cell coverage area according to the antenna patterns in a sector base station. More particularly, the present invention relates to a method for determining the practical number of base stations required in an actual working environment.
In general, it is necessary to consider both the traffic capacity and the coverage areas of a cell, simultaneously, in order to determine the effective number of base stations required for providing communication service in a given system. Thus, the effective number of base stations can be determined by considering two factors, the minimum number of the base station based on the coverage area and the minimum number of the base stations based on the traffic capacity. [The number of the base transceiver stations=MAX [min(area based), min(traffic based)].
The minimum number of the base stations based on the coverage area is calculated by dividing the total service area by the service area to which a base station can render service. The service area of a base station is calculated by analyzing a link budget using various parameters, and then calculating a cell radius according to the maximum allowable path loss through applying an appropriate propagation model. This path loss estimate is then used in the mobile cell-site link budget equation, solving for the mobile unit transmit power required to produce a desired signal level.
If the antenna gain of a sector base station and an omni base station is identical with each other, the effective coverage area of the sector system having a directional antenna is less than the area of the omni system with an omni-directional antenna.
FIG. 1 illustrates a method for determining coverage area of each base station in a sector system. Generally, in a single cell of the omni-system, the coverage area S of a base station is an area of a circle having a cell radius R (S=xcfx80R2). Since, it is too difficult to determine the exact coverage area for each base station in multi-cell omni-system, the coverage area of a base station has been calculated on the basis of a hexagonal type cell model to account for the handover area.
In the omni system using the omni-directional antenna, it is suitable to calculate the coverage area of each base station, using the formula as stated in the previous paragraph. However, in a directional antenna used in the sector system, the coverage area for each base station depends on the antenna patterns. Thus, if the antenna gain of two systems were identical, the coverage area for each base station in the sector system is smaller than the omni system. In order to determine the coverage area for the sector system, the effective area should be calculated considering the hexagonal type cell model as well as antenna patterns. FIG. 2 illustrates change of the coverage area in a base station according to the antenna patterns in the sector system.
It is an object of the present invention to provide a method for determining an effective coverage area in the sector base station by providing a ratio of the coverage areas between the sector base station and the omni base station according to horizontal beam antenna patterns, which is then used to determine the number of the base stations required to provide communication service in a given system.
A preferred embodiment of a method for determining a coverage area according to antenna patterns in a sector base station system includes the steps of:
calculating the ratio of the coverage area of the sector base station to the omni base station;
calculating the coverage area of the omni base station considering a handover area;
applying the calculated ration to determine the coverage area of the sector base station, by multiplying the calculated ratio of coverage area of the sector base station by the calculated coverage area of the omni base station;
providing the number of the sector base stations required in a wireless system by dividing the total coverage area of the wireless system by the determined coverage area of the sector base station.
In the embodiment, it is preferable that said step for calculating the coverage area according to antenna pattern of the sector base station further comprises the steps of:
determining a radius for each antenna angle to yield a maximum allowable path loss according to the horizontal beam antenna patterns;
calculating a circle area for each antenna angle and dividing each calculated circle area by 360; and,
determining the effective coverage area for the sector base station according to the horizontal beam antenna patterns by summing up each calculated area for each antenna angle.
And it is preferable that the coverage area of the omni base station considering a handover area is calculated by                     3        xc3x97                  3                    2        xc3x97          R      2        ,
where R represents a cell radius.
And it is preferable that the antenna position of a base station is apart from each other by an angle of 120xc2x0.