Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-11-17
2001-02-13
Eisenzopf, Reinhard J. (Department: 2745)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S424000, C455S067150, C455S446000, C455S449000
Reexamination Certificate
active
06188894
ABSTRACT:
FIELD OF THE INVENTION
The present invention is generally related to wireless cellular-type communication systems, and more particularly to the evaluation of geographical coverage of the cells and associated cell boundaries to determine poor performance areas.
BACKGROUND OF THE INVENTION
There is desired the ability to geographically identify the various cell layers for an existing wireless communications network, and correspondingly identify geographical areas requiring performance improvement. This method should be applicable to any cellular-type communications network which utilizes base stations geographically spaced in a desired coverage area. The method should be applicable to omni-directional or sectored site configurations. This methodology should also be applied to macrocell, microcell and picocell environments (hierarchical cell structures). A cell layer, in this context, is defined as a grid of hexagons, each hexagon having a “cell” radius, r.
Today, cellular grids are overlaid onto a system during the system design cell planning process and the grid locations are “populated” in order to satisfy coverage and capacity requirements. Generally, hexagons represent the theoretical relations i.e. borders between cells. The system accommodates growth needs by the addition of base stations, which help mitigate interference and capacity problems in the system. Normally, these sites are positioned on “vacant” grid locations.
In order to analyze performance problem areas in an existing cellular-type wireless system, it is necessary to gather customer complaint information and/or switch (MTSO) statistics corresponding to cells (sectors). Drive testing may be necessary in order to validate problems. Cell boundaries are often determined via composite propagation predictions (best server plots).
Due to zoning restrictions and fast system growth, the startup cellular type system grids become “skewed”, whereby it is difficult to determine the theoretical boundaries for the cells. Subsequently, cells may not be ideally positioned at the center of the hexagon. The relationship between actual and theoretical cell boundaries is no longer apparent. This leads to performance problems in the system, which can be coverage or interference based. Moreover, when many new base station locations are added to the system, it becomes increasingly difficult to differentiate one grid layer from another. Performance analysis, in turn, becomes cumbersome because cell boundaries associated with various cell layers are near impossible to determine geographically.
It is necessary to provide a methodology, which can be automated, that identifies the various cell layers in an existing wireless system and, accordingly, the cell sizes associated with these layers. A “snapshot” of a cellular-type wireless system should be provided and utilized as a baseline for further analysis of poor performance problems.
SUMMARY OF THE INVENTION
The present invention achieves technical advantages as a cell coverage evaluation method by utilizing existing base station geo-referenced information (latitude/longitude) and determining the average site-to-site distance for each site in the system. Accordingly, utilizing the geometrical relationship between the site-to-site distance and the cell radius, an average cell radius is then calculated for each site in the wireless system based on the average site-to-site distance. The various cell layers (grids) are then identified for the entire system. Cell sizes are determined for each cell (sector) in the system. All cell layers or grids are then overlaid as a “composite” snapshot to reveal poor performance areas (holes) which are utilized as a baseline for further investigation/analysis.
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patent: WO 98/27773 (1998-06-01), None
Eisenzopf Reinhard J.
Ericsson Inc.
Navarro Arthur I.
Ramos-Feliciano Eliseo
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