Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-12-21
2002-10-15
Bost, Dwayne (Department: 2681)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S461000, C701S213000
Reexamination Certificate
active
06466788
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to communications systems, and more particularly, to the transfer of data regarding geographic positions of mobile terminals and mobile terminal users in wireless communications systems.
BACKGROUND OF THE INVENTION
Wireless communications systems are pervasive in the world today. For example, a significant percentage of individuals in developed nations already personally own at least one cellular telephone for use with well established land-based and satellite-based systems. Furthermore, a growing number of developing nations are now bringing wireless systems on line. This insatiable global appetite for wireless technology will only intensify in the foreseeable future.
FIG. 1
depicts an exemplary wireless communications system
100
including ten cells or coverage areas C
1
-C
10
, ten base stations B
1
-B
10
, a Mobile Switching Center MSC and ten mobile stations M
1
-M
10
. Such a wireless system
100
can be constructed, for example, in accordance with any of the well known wireless communications standards, including the European Global System for Mobile (GSM) cellular standard or the United States Digital Cellular (USDC) standard (i.e., the Electronic Industry Association Interim Standard IS-54). While such a system
100
typically includes far more than ten cells, ten base stations and ten mobile stations, ten of each component is sufficient for illustrative purposes.
As shown, one or more base stations can be situated in each of the cells. Although
FIG. 1
shows the base stations located toward the cell centers, each base station can instead be located anywhere within a cell. Base stations located toward a cell center typically employ omni-directional antennas, whereas base stations located toward a cell boundary typically employ directional antennas. Those skilled in the art will also appreciate that each individual base station shown in
FIG. 1
can, in practice, comprise a base station controller in communication with a number of separate base station units, each unit providing coverage for a cell sector.
Typically, each base station and each mobile station includes a radio transceiver for transmitting and receiving communications signals over the air interface (as defined, for example, by one of the known standards, GSM, IS-54, etc.). More specifically, the base and mobile stations communicate using a form of time, frequency or code division multiple access (i.e., TDMA, FDMA or CDMA) as is known in the art. As the mobile stations move within a cell and from cell to cell, communication with at least one base station is always possible. As a result, mobile station users are able to place, receive and conduct calls from anywhere within the overall system coverage area.
As shown, the base stations are also in communication with the MSC. Though only one MSC is shown in
FIG. 1
, those of skill in the art will appreciate that an overall system typically includes multiple MSCs, each MSC being coupled (e.g., by radio or hard-wire link) to a unique subset of the base stations in the overall system, and each MSC being capable of communicating with the other MSCs in the system (e.g., via the U.S. Signaling System No. 7, or SS7, protocol). As is known in the art, the MSCs keep track of which cells the mobile stations are registered in and provide a link between the wireless system
100
and the Public Switched Telephone Network (PSTN).
To keep track of which cells the mobile stations are registered in, each MSC typically maintains a Visiting Location Register (VLR) which provides a list of mobile stations presently registered within the coverage area of the MSC (i.e., in the coverage area serviced by all of the base stations which are coupled to the MSC). Furthermore, at least one Home Location Register (HLR) is typically maintained for an overall system, the HLR conventionally providing a list of all local subscribers based within the system coverage area and also providing, for each local subscriber, a description of the various features available to the subscriber. When a mobile station moves into a new coverage area and registers with a new MSC (via a coupled base station), the visited MSC updates its VLR to reflect the presence of the mobile station and also contacts the HLR to obtain subscription information for the mobile station. In this way, mobile stations can seamlessly roam from coverage area to coverage area while maintaining the ability to place and receive calls in accordance with their base subscription.
Conventionally, there has been a strong connection between a wireless subscription and a particular mobile terminal and a particular mobile user. In other words, an individual user conventionally purchases a subscription with which a particular terminal is associated (e.g., by Mobile Identification Number, or MIN), and the individual user is charged for calls placed from the particular terminal. Additionally, calls are conventionally placed by dialing a number associated with a particular terminal, and thus varying numbers are used to reach an individual, depending upon which of many terminals the individual happens to be near.
More recently, however, the growing demand for wireless technology has required a more sophisticated approach to system management. In particular, there has been a recent push toward a global system in which calls are made, not from terminal to terminal, but from user to user. In other words, a system in which each user has a unique identification number by which all calls to that user are placed, irrespective of which terminal the user happens to be using. Toward that end, the concepts of user, terminal and subscription are beginning to diverge. See, for example, co-pending U.S. patent application Ser. No. 08/585,149, filed Jan. 10, 1996 and entitled Cellular Telecommunication Systems having Selectively Associatable Usage Parameters, which is incorporated herein by reference. Consequently, the above described Home and Visiting Location Registers can now include distinct user, terminal and subscription databases.
Recently (e.g., with the advent of the Global Positioning System, or GPS), there has also been a push toward enabling a wireless communications system to provide detailed information regarding the geographic position of users and terminals. However, while the MSCs in a conventional wireless system can determine the cell in which a mobile terminal is located, they typically cannot provide the more precise location information which is often necessary or desirable in practice (e.g., when an individual must be located in an emergency situation or when system operations personnel wish to locate a particular terminal for maintenance or repair). Further, known methods for providing more precise location information (see, e.g., U.S. Pat. No. 5,727,057 to Emery et al.) do not account for the recent divergence of the concepts of user, terminal and subscription.
Consequently, there is a need for improved techniques for ascertaining the geographic location of a mobile terminal in a wireless communications system.
SUMMARY OF THE INVENTION
The present invention fulfills the above-described and other needs by providing methods and apparatus for ascertaining the geographic position of users and terminals in a wireless communications system. Embodiments of the invention enable system users to easily request the position of a terminal (e.g., when operations personnel wish to locate a terminal in order to perform maintenance of traffic system performance or to determine the reasons for lost calls) or the position of a user (e.g., when emergency personnel wish to locate a lost or injured individual). Further, embodiments of the invention permit mobile terminals to be used as navigation instruments and open the door to more sophisticated supervision of taxis, buses and other transport vehicles. Advantageously, aspects of the invention can be readily incorporated within a wireless communications protocol which contemplates the distinct concepts of user, terminal and subscription.
An exemplary me
Bost Dwayne
Burns Doane Swecker & Mathis L.L.P.
Telefonaktiebolaget LM Ericsson (publ)
West L
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