Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-08-06
2003-06-17
Urban, Edward F. (Department: 2684)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S067700, C455S067700, C455S422100, C455S423000, C455S448000, C455S449000
Reexamination Certificate
active
06580911
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to wireless communication systems, and, more particularly, to methods and arrangements for enhancing the accuracy of modeled information within a clutter database and related modeling tools associated with a mobile telecommunications network.
2. Description of Related Art
There is a continuing need to accurately determine or otherwise predict the amount of power required for up-link and down-link radio transmissions between a mobile station, such as, for example, a cellular telephone, and a base station. Providing such capabilities often requires that information be gathered about the actual terrain and other obstacles within the coverage area (e.g., cell) of the base station. This information is typically stored within a clutter database and utilized in modeling the propagation characteristics for the coverage area.
For example, a clutter database can be used as an overlay to the terrain database in a propagation prediction tool. “Clutter”, as used herein, is defined to be anything above ground level that may mitigate or otherwise modify the RF signal transmitted by a wireless communications base station or mobile station.
Today, clutter databases are typically developed based on information acquired via mapping data, such as, for example, U.S. Geological Survey (USGS) topographical maps. Additional information can be empirically collected in the field. For example, actual received signal level (RSL) data can be collected by drive testing selected portions of a coverage area.
The resulting clutter database(s) that are developed today tend to apply predefined clutter classifications based on certain clutter types identified within a defined region of the coverage area. The threshold utilized in assigning clutter classifications may vary, but typically a clutter classification is assigned to a defined region if more than 50% of the defined region within the coverage area is of one type of clutter.
Developing accurate clutter databases can be very expensive. The size of the defined regions within coverage areas determines the clutter database bin size. The smaller the bin sizes, the more expensive the clutter database. To reduce costs and simplify modeling techniques, the bin size is typically uniform throughout the coverage area. Thus, a coverage area is typically subdivided into defined regions (bins) having the same area.
The clutter classification or value assigned to each bin is usually based on historical information built through a system operator's experience with the wireless system and/or collected by drive testing the corresponding region. This is a very time consuming process, especially if the system is a new system, where clutter data is scarce or non-existent. Moreover, the values for clutter vary over time as new buildings are constructed, old buildings are demolished, trees grow or are removed, etc. Additionally, the characteristics associated with certain types of clutter can change from time to time. For example, the clutter values associated with trees can vary significantly depending on the time of year, as leaves are grown and later shed.
It should, therefore, be understood that the costs associated with maintaining and/or updating the accuracy of such a clutter database can be extremely high. Furthermore, there is no clear-cut efficient methodology for determining more exact clutter values for the clutter database, especially on a seasonal or time domain basis.
In relation to wireless communication systems, there can also be overlapping coverage areas (cells). For example, several base stations can provide radio coverage to a defined region. Consequently, cell planning would be inaccurate if a gross classification were utilized for the region, particularly if radio coverage is provided by both small cells (microcells), implemented for capacity relief, and large cells (macrocells).
Thus, there is a need for improved methods and arrangements that not only identify the clutter types, but are also capable of providing different resolutions, as required to model the clutter accurately for both small cell and large cell applications. The bin sizes (resolution), as well as the clutter definitions for those bins (type and loss/gain values), need to be accurately identified by the improved methods and arrangements, preferably without requiring extensive field testing. The improved methods and arrangements of the present invention are also preferably easy to implement, automate, and/or adapt to existing propagation models and/or mobile telecommunication systems.
SUMMARY OF THE INVENTION
The present invention provides improved methods and arrangements that identify clutter types by providing different resolutions of bin sizes that can be used to model the clutter accurately for both small cell and large cell applications. This improved resolution increases the accuracy of the clutter information without requiring extensive field testing. The methods and arrangements are also easy to implement, automate, and/or adapt to existing propagation models and mobile telecommunication systems.
In accordance with certain aspects of the present invention, an improved methodology is provided for enhancing the information in a clutter database that is part of a propagation prediction tool. For example, supplemental information from aerial photography and/or satellite imagery is incorporated into a clutter database to allow for different sized bins and resulting resolutions. In accordance with still other aspects of the present invention, the accuracy of information in a clutter database is enhanced with supplemental information acquired from existing wireless communication subscribers. In accordance with still other aspects of the present invention, expected transmission parameters, e.g., power transmission levels, are determined based on information in a clutter database and dynamically provided to a mobile telecommunications system, e.g., to a mobile station and associated base station to adjust the power transmission levels therebetween.
Thus, for example, in accordance with certain embodiments of the present invention, a method is provided for use in updating a clutter database. The method includes defining at least one bin within at least one coverage area of a base radio station using geographical data, and collecting supplemental data that further identifies the physical environment of the bin with respect to clutter types that alter radio signals propagating through at least a portion of the bin. The method further includes the steps of fusing the supplemental data with the geographical data, identifying sub-bin portions of the bin that have distinct clutter types, associating an identifier to each of the sub-bin portions, and storing the respective identifiers for each identified sub-bin portion in a clutter database.
In accordance with certain further embodiments, the step of defining at least one bin within at least one coverage area of the base radio station, further includes accessing a topographical mapping service to provide the geographical data. In still other embodiments the step of collecting supplemental data, further includes accessing an aerial photography service, a satellite imagery service, an empirical data service, and/or at least one mobile telecommunication system resource to provide the supplemental data.
In still other embodiments the step of fusing the supplemental data with the geographical data, further includes adjusting a scale of the supplemental data to match a resolution associated with the geographical data, and/or adjusting a scale of the geographical data to match a resolution associated with the supplemental data.
The above methods can be further adapted for analysis by a system operator or engineer by modifying the step of identifying sub-bin portions of the bin that have distinct clutter types to include identifying clutter types by a color-code and/or numerical scheme.
The above-stated needs and others are also met by an arrangement for
Ericsson Inc.
Jenkens & Gilchrist P.C.
Urban Edward F.
Zewdu Meless
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