Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1997-07-03
2001-03-06
Tsang, Fan (Department: 2746)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S457000, C455S525000, C455S575100, C455S334000, C342S357490, C342S357490
Reexamination Certificate
active
06198930
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to determination of which service zone a roving or mobile cellular phone has entered and automatic transmission of this information to a cellular phone service provider.
BACKGROUND OF THE INVENTION
The number of cellular phone users in the U.S. is now estimated at about 17 million and continues to grow at a rate exceeding 20 percent per year. Most of this growth in use has occurred in and around cities and towns with populations of 20,000 or more and has caused saturation of the channels available for cellular communication in many of these urban areas. Cellular service zones, referred to herein as “cellzones” for convenience, each servicing about 800 cellular telephone communications, have decreased in size from several miles in diameter to a few hundred meters in diameter as the density of cellphone users has increased apace in urban and suburban areas.
A cellphone subscriber will typically register use of a cellphone in a home cellzone and will temporarily re-register in one or more nearby cellzones if the subscriber makes or receives cellphone calls in these other cellzones. However, even where the cellphone subscriber is already registered in one or more nearby cellzones, the operator of any cellzone will typically be unaware of the presence of this subscriber in this cellzone, unless this subscriber has either recently requested cellular service in this zone or has somehow notified the operator that the subscriber is currently present in this zone. Knowledge of the number of cellphone subscribers currently in a given cellzone, who are not all active users of the cellular phone service at any given moment, may allow the service operator to rationally plan its present provision, and future expansion, of cellular service to accommodate the increasing demands.
A personnel locator system is disclosed in U.S. Pat. No. 3,439,320, issued to Ward. Each person carries a sensor/transmitter that emits a unique frequency whenever that person enters any one of a plurality of selected areas in a facility, with each such area having a receiver that receives this signal and transmits this information to a central processor. The processor keeps track of the movements of each person from one selected area to another area so that, at any given time, the processor can identify the selected area a given person now occupies. This approach is limited to a relatively small geographic area and to a relatively small number of covered persons.
Serrano et al disclose a microprocessor-controlled interface for a cellular phone system to be carried in a vehicle, in U.S. Pat. No. 4,718,080. A telephone handset communicates with the cellular transceiver along a bus and through the microprocessor that interprets bus logic signals, including voice and data signals. No integration is disclosed of the on-board cellular system with any instrument that reports vehicle operating information upon command received from a remote site.
U.S. Pat. No. 4,797,671, issued to Toal et al, discloses a motor vehicle locator system that indicates the location of a parked vehicle within a controlled area, such as a large parking lot. Each parked vehicle carries a receiver and audio/visual signal emitter. The receiver responds only to receipt of a signal having a unique frequency and causes the emitter to emit an audible or visually perceptible signal that indicates the present location of the parked vehicle. This approach requires that the vehicle be located within a controlled area of modest size, probably no larger than a city block.
Ando et al, in U.S. Pat. No. 4,837,700, disclose method and apparatus for processing and displaying the present location of a road vehicle, using a GPS receiver to provide data on vehicle location. This approach provides continuous information on vehicle location and vehicle orientation or vehicle movement vector based upon sensing the Earth's local geomagnetic field direction. An angular rate sensor determines, and optionally displays, the angular rate of change of vehicle orientation, and an odometer determines the distance the vehicle has moved over some predetermined time interval. The present vehicle location can be displayed graphically on an electronic map carried within the vehicle, with a sequence of maps being used to display the changing vehicle location. Map size can also be increased or decreased, and the displayed map can be automatically scrolled as vehicle position changes. A keyboard is available for entering instructions into a controller or processor. A reference location can be entered into the system, and vehicle location can be determined relative to this reference location. The location data can be stored if these data are acceptable and can be dumped into a bit bucket if these data are not acceptable.
In U.S. Pat. No. 4,924,402, Ando et al disclose a more detailed approach for determining and graphically displaying vehicle location using a GPS. This system uses a magnetic field sensor, an angular velocity sensor and a travel distance sensor together with GPS data and stores maps together with numerical data that describe useful features of the local terrain. Sensing of vehicle distance traveled and directional turns made is intended to be sufficiently accurate that the map displays the location of the vehicle relative to road intersections (i.e., approaching, passing trough, turning, etc.). With reference to
FIGS. 16-17
,
22
,
27
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28
and
30
of the Ando et al patent, the invention appears to put a premium on receiving GPS data that are accurate to within one meter.
A paging system with paging request receivers that respond or are controlled differently, depending upon receiver location, is disclosed by Vrijkorte in U.S. Pat. No. 4,943,803. Using “angle modulation” whose operation is not explained, the paging request receiver is said to pick out the strongest transmission control signal from among simultaneously transmitted control signals and to respond to this signal, if the signal received includes the receiver's predetermined address code. The receiver goes into a “sleeper” mode if no signals specifically addressed to that receiver are received within a selected time interval. The receiver is activated for receiving a control message by receipt of a receiver activation signal that may vary with the geographic zone presently occupied by the receiver.
Nishikawa et al disclose a land vehicle navigation system in U.S. Pat. No. 4,949,268. A combination of three or more GPS satellites is selected, from among all available GPS satellites, that provides the best vehicle location data. Here, a figure of merit used is minimum position dilution of precision (“PDOP”) associated with the data received from a given group of GPS satellites. This approach seeks to account for the possibility that one or more buildings or other structures of relatively great height may preclude satellite visibility. The height of the structures in that area may be stored as part of a map in a GPS processor on board the land vehicle whose location is to be determined. The on-board system seeks combinations with the highest number of satellites visible, then works from these combinations to minimize the PDOP or a similar figure of merit for GPS position data.
Scribner et al disclose a vehicle tracking system that records, but does not transmit, the location of a vehicle whenever one or more predetermined events occurs in U.S. Pat. No. 5,014,206. The vehicle carries sensors that respond to occurrence of a predetermined event and carries a GPS or LORAN navigational system that receives vehicle location information, such as longitude and latitude. This vehicle location information is stored in a memory on board the vehicle only when one or more of the predetermined events occurs. The vehicle location information is assumed to be read out periodically when the vehicle returns to a home base.
In U.S. Pat. No. 5,043,736, Darnell et al disclose use of a combined cellular telephone and GPS portable receiver system that provides latitude and longitud
Schipper John F.
Sobutka Philip J.
Trimble Navigation Limited
Tsang Fan
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