Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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NETWORK BASED METHOD AND APPARATUS
FOR RESTRICTING OPERATION OF CELLULAR
TELEPHONES TO DELINEATED GEOGRAPHICAL AREAS
CROSS-REFERENCE TO RELATED APPLICATION
The present application is a continuation-in-part of
co-pending U.S. Application Patent for Serial Number
08/759,997, filed on December 4, 1996, entitled "METHOD
AND APPARATUS FOR RESTRICTING OPERATION OF CELLULAR
TELEPHONES TO WELL DELINEATED GEOGRAPHICAL AREAS," by Eric
Valentine and Vladimir Alperovich.
BACKGROUND OF THE INVENTION
Technical Field of the Invention
The present invention pertains in general to the
planning and deployment of a wireless telephone system,
and more particularly, to restricting the operation of
wireless telephones to delineated geographical locations
wherein the geographical location of the wireless
telephone is ascertained by the wireless telephone system.
Description of Related Art
It is often desirable to prohibit operation of
wireless telephones in certain geographical locations.
For example, use of wireless telephones is prohibited in
airplanes while on a runway preparing for take-off.
Operation is also prohibited in areas of hospitals where
wireless telephone transmissions might interfere with life
critical equipment. Furthermore, as the service area of
wireless telephone systems grow, such as through the use
of satellite based systems providing national coverage,
it is desirable to prohibit operation in larger
geographical areas such as on military bases.
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It has been proposed to equip wireless telephones
with locating devices such as Global Positioning System
(GPS) receivers which ascertain the geographical location
of the wireless telephone. Service is then denied to
mobile stations having an ascertained geographical
location within a restricted area. Such systems, however,
are expensive and the GPS receiver consumes the limited
battery power available to wireless telephones. It would
be advantageous therefore, to develop a method and
apparatus wherein the wireless telephone system itself
ascertains the location of the wireless telephone and
controls the disabling of telephone operation when the
telephone is located in an unauthorized location.
SUMMARY OF THE INVENTION
A wireless telephone system operates to ascertain the
geographical location of wireless telephones. In a
satellite based wireless telephone system, the wireless
telephone system may ascertain the geographical location
through a mapping of the position of the wireless
telephone in a satellite reference coordinate system, and
then converting the position to an earth reference
coordinate system. In another embodiment, the wireless
telephone system may ascertain the geographical location
through triangulation using a plurality of satellites or
base stations which monitor wireless telephone signal
transmissions. Regardless of the mechanism used for the
system to determine location, a comparison is made between
the ascertained geographical location and database
information pertaining to authorized/un-authorized
geographical locations to determine whether telephone
operation is authorized. A controller within the wireless
telephone system then instructs the wireless telephone to
disable itself when the wireless telephone is determined
to be located in an unauthorized location and enable
itself when located in an authorized location.
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BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the method and
apparatus of the present invention may be acquired by
reference to the following Detailed Description when taken
in conjunction with the accompanying Drawings wherein:
Figure 1 is a diagram of a satellite based wireless
telephone system incorporating the present invention;
Figure 2 is a terrestrial based wireless telephone
system incorporating the present invention; and
Figure 3 is a flow diagram of a method for
implementing the present invention in a wireless telephone
system.
DETAILED DESCRIPTION OF EMBODIMENTS
Referring now to Figure 1, there is illustrated a
satellite based wireless telephone system 90 including a
plurality of the satellites 100A-C, a terrestrial portion
110 of the wireless telephone system 90, and a database
120. Each of the plurality of satellites 100A-C
communicates with the terrestrial portion 110 of the
wireless telephone system 90. Although more than one
satellite of the plurality of satellites 100A-C may
receive transmissions from a wireless telephone 130,
typically only one satellite 100A communicates with the
wireless telephone 130 at any given time. Communication
between the wireless telephone 130 and a public switched
telephone network 140 is established via the plurality of
satellites 100A-C and the terrestrial portion 110 of the
wireless telephone system 90. Also included in the
terrestrial portion 110 of the wireless telephone system
90 is a first controller 150 which instructs a second
controller 133 within the wireless telephone 130 to
disable or enable operation based on the location of the
wireless telephone 130.
Several methods are known in the industry for
ascertaining the geographical location of a radio
transmission source such as the wireless telephone 130.
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For example, in a satellite based wireless telephone
system a method known as Satellite To Earth (SATTOE) maps
a position of the wireless telephone 130 in a satellite
reference coordinate system and then converts the position
to an earth reference coordinate system. The satellite
to earth mapping operation uses a well known rotation
transformation matrix, knowledge of a satellite antenna
beam footprint, the position of the satellite, and the
communication path of the satellite to determine a rough
geographical location of the wireless telephone 130. To
obtain the location of the wireless telephone 130 with a
higher degree of resolution the satellite to earth mapping
operation uses additional information such as the results
of calculations performed on a Random Access Channel
(RACH) and a Dedicated Control Channel (DCCH). Another
well known method to determine the geographical location
of the wireless telephone 130 in the satellite based
wireless telephone system 90 uses two or more satellites
100A-C to triangulate the geographical location of the
wireless telephone 130.
Using any known method, the wireless telephone system
90 ascertains the geographical location of the wireless
telephone 130 and accesses the database 120 which contains
information pertaining to the authorization to operate the
wireless telephone 130 in the ascertained geographical
location. Based on a comparison of the information
contained in the database 120 against the ascertained
geographical location, the first controller 150, which is
part of the wireless telephone system 90, determines
whether operation is authorized. If operation is
unauthorized the first controller 150 transmits a command
via the satellite 100 instructing the wireless telephone
130 to disable itself. The second controller 133, located
in the wireless telephone 130, receives the command via
a transceiver 132 and disables the wireless telephone 130.
On the other hand, if operation is authorized the first
controller 150, transmits a command via the satellites 100
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instructing the wireless telephone 130 to enable itself.
The second controller 133 receives the command via the
transceiver 132 and enables the wireless telephone 130.
Referring additionally now to Figure 2, there is
illustrated a terrestrial based wireless telephone system
190 including a plurality of base stations 200A-C, a
database 120, and a plurality of controllers 250A-C. Each
of the plurality of base stations 200A-C communicates with
the database 120. Although more than one base station of
the plurality of base stations 200A-C may receive
transmissions from a wireless telephone 130, typically
only one satellite 200A (Figure 1) communicates with the
wireless telephone 130 at any given time. Also included
in the base stations 200A-C are controllers 250A-C which
are capable of instructing the controller 133, located
within the wireless telephone 130, to disable and enable
operation of the wireless telephone 130.
Several methods are known in the industry for
ascertaining the geographical location of the wireless
telephone 130 in a terrestrial based wireless telephone
communication system. For example, the wireless telephone
system can use two or more of the base stations 200A-C
to
triangulate the geographical location of the wireless
telephone 130. Another approach uses knowledge of which
base station 200A is communicating with the wireless
telephone 130 and Timing Advance (TA) information used
in
wireless communication between the base station 200A and
the wireless telephone 130 to ascertain a rough estimate
of the geographical location.
Using any known method, the wireless telephone system
190 ascertains the geographical location of the wireless
telephone 130 and accesses the database 120 containing
information pertaining to the authorization to operate
the
wireless telephone 130 in the ascertained geographical
location. Based on a comparison of the information
contained in the database 120 against the ascertained
geographical location, the controller 250A of the base
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station 200A serving the wireless telephone 130 determines
whether operation is authorized. If operation is
unauthorized the controller 250A, located in the base
station 200A, transmits a command instructing the wireless
telephone 130 to disable itself. The controller 133,
located in the wireless telephone 130, receives the
command via the transceiver 132 and disables the wireless
telephone 130. On the other hand, if operation is
authorized, the controller 250A transmits a command
instructing the wireless telephone 130 to enable itself.
The controller 133, located in the wireless telephone 130,
receives the command via the transceiver 132 and disables
the wireless telephone.
Referring additionally now to Figure 3, there is
illustrated a flow diagram of a method for implementing
the present invention in a wireless telephone system.
During operation of the wireless telephone the wireless
telephone system periodically ascertains the geographical
location of the wireless telephone (step 300). Any known
method of ascertaining the geographical location of the
wireless telephone can be used including, but not limited
to, mapping the position of the wireless telephone in a
satellite reference coordinate system to an earth
reference coordinate system, or by triangulation using
multiple components of the wireless telephone system.
Once the geographical location is ascertained, the
location is compared against database information
pertaining to the authorization to operate in the
ascertained location (step 305) and a determination is
made as to whether operation is authorized (step 310).
If it is determined that operation is unauthorized a
controller within the wireless telephone system instructs
the wireless telephone to disable itself (step 330). On
the other hand, if it is determined that operation is
authorized the controller instructs the wireless telephone
to continue operation or enable itse,f if disabled (step
340) .
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Although embodiments of the method and apparatus of
the present invention have been illustrated in the
accompanying Drawings and described in the foregoing
Detailed Description, it will be understood that the
invention is not limited to the embodiments disclosed, but
is capable of numerous rearrangements, modifications and
substitutions without departing from the spirit of the
invention as set forth and defined by the following
claims.
