1. Field of the Invention
The invention is generally directed to antennas and loads on antennas created by wireless communication.
2. Description of Related Art
Wireless communication systems typically involve information from individual wireless or landline callers being sent to and from other wireless or landline callers via base stations and wireless communication switching centers. Each base station typically includes three antennas, or a single three component antenna 20 as shown in prior art FIG. 1 (which is most times a 3 pole or 3 component antenna as represented by element 20A, 20B and 20C). The coverage area or cell 10 serviced by the base station antenna 20 varies in size, depending upon the strength or power of the antenna; the distance between base station antennas 20; and other various parameters.
Base station antenna 20 typically includes three antenna components 20A, 20B and 20C, each component being set up and remaining in a fixed position. Each of the three antenna components 20A, 20B and 20C provides a fixed beam pattern and orientation covering a fixed sector such as that shown in FIG. 1, and represented by elements 30A, 30B and 30C. The beam patterns 30A-C as shown in FIG. 1 dictate the area or sector from which information can be received from wireless communication units and to which information can be sent.
In one aspect of a wireless communication, namely in cellular/PCS, code division multiple access (CDMA) technology provides for a large capacity of information to be communicated. The capacity in a CDMA system, in essence, does not have a hard limit. Problems occur, however, due to limits of the antenna 20 as shown in FIG. 1, created by the fixed beam patterns and orientations, and the fixed sectors of coverage 30A, 30B and 30C. Basically, although each component 20A, 20B and 20C of antenna 20 covers a certain fixed sector or area of the cell 10, wireless activity or traffic between sectors within the cell 10 may not be equal. Thus, a need exists for dynamically distributing the traffic load among various antenna components and coverage sectors within a cell.
Further, each cell 10 includes neighboring cells as shown by the dashed lines in FIG. 1, with each neighboring cell similarly including a base station antenna 20 with the antenna components 20A, 20B and 20C, for handling a traffic load within the neighboring cell. However, while traffic loads can vary among sectors within a cell, traffic loads can also vary from cell to cell. Thus, a need exists for dynamically distributing traffic load among neighboring cells.
In current CDMA systems, with cells including antennas 20 and antenna sector components 20A, 20B and 20C including fixed beam patterns and orientations, one known way of achieving some dynamic load sharing functionality between cells is by adjusting transmit power of the base station within a certain range. However, this only achieves a very limited amount of dynamic loading sharing. Further, any reduction in base station transmit power may potentially create a coverage hole where a wireless communication call may inadvertently be dropped or unable to be connected. Thus a need for a better way to dynamically distribute a traffic load among neighboring cells exists.
When a cell is heavily loaded, it may reject requests to establish and handle a new wireless call. Further, it may also deny soft handoffs to another base station in a neighboring cell when the traffic load gets too heavy. Each of these can cause degradation in the performance and restriction on capacity of the overall system. Finally, in the real world, traffic load distributions are extremely non-uniform and time varying, thus creating more of a need for dynamic load sharing within cells and among neighboring cells.
A system and method have been developed wherein a cylindrical antenna array is used in a system involving dynamic load sharing. Antenna component configurations of the cylindrical antenna array are adjusted, including beam configuration and orientation for example, based on the determined load to thereby vary antenna coverage areas or sectors to accommodate varying traffic densities. The dynamic load sharing can accommodate such variations within a cell, and/or between cells.
USPTO Backgrounds
USPTO Backgrounds