US5815538A — Method and apparatus for determining location of …

Claim 1

Independent Claim 175 words

A method for determining a location of a subscriber device in a wireless cellular communications system, comprising the steps of: providing a subscriber device having a cellular digital data receiver system with a cellular digital data receiver therein; transmitting cellular digital data signals to the subscriber device from at least three different cellular cell site transmitters at different but known locations, each data signal containing a time-synchronized synchronization signal, the time-synchronized synchronization signals of the at least three different cellular cell site transmitters being transmitted at the same time or being displaced in time from each other by a known time displacement; informing the subscriber device of location data representing a location of each of the at least three cellular cell site transmitters; determining a time of arrival of each of the time-synchronized synchronization signals with respect to an internal clock of the cellular digital data receiver system; and obtaining the location of the subscriber device from the location data and the times of arrival of the time-synchronized synchronization signals relative to the internal clock.

Claim 2

Independent Claim 175 words

A method for determining a location of a subscriber device in a wireless cellular communications system, comprising the steps of: providing a subscriber device having a cellular digital data receiver system with a cellular digital data receiver therein; transmitting cellular digital data signals to the subscriber device from at least three different cellular cell site transmitters at different but known locations, each data signal containing a time-synchronized synchronization signal, the time-synchronized synchronization signals of the at least three different cellular cell site transmitters being transmitted at the same time or being displaced in time from each other by a known time displacement; informing the subscriber device of location data representing a location of each of the at least three cellular cell site transmitters; determining a time of arrival of each of the time-synchronized synchronization signals with respect to an internal clock of the cellular digital data receiver system; and obtaining the location of the subscriber device from the location data and the times of arrival of the time-synchronized synchronization signals relative to the internal clock.

Claim 3

Dependent Claim 29 words

The method of claim 1, wherein the step of transmitting includes the step of synchronizing the time-synchronized synchronization signals to a timing signal provided by a global positioning system.

Claim 4

Dependent Claim 44 words

The method of claim 1, wherein the step of informing includes the step of incorporating into the cellular digital data signal transmitted from at least one cell site the location data representing the location of each of the at least three cell site transmitters.

Claim 5

Dependent Claim 68 words

The method of claim 1, wherein the step of determining includes the steps of aligning the internal clock of the cellular digital data receiver system to a first one of the time-synchronized synchronization signals transmitted at a first time, and establishing the arrival times of a second and a third later-transmitted time-synchronized synchronization signals of respective second and third cell site transmitters relative to the aligned internal clock.

Claim 6

Dependent Claim 18 words

The method of claim 1, wherein the step of obtaining is performed by the cellular digital data receiver.

Claim 7

Dependent Claim 39 words

The method of claim 1, including the additional step of transmitting the relative time of arrival of each of the time-synchronized synchronization signals to a remote location, and wherein the step of obtaining is performed at the remote location.

Claim 8

Dependent Claim 25 words

The method of claim 1, wherein the step of transmitting includes the step of providing time-synchronized synchronized signals having no intentionally introduced time displacements therein.

Claim 9

Dependent Claim 61 words

The method of claim 1, including the additional step of time displacing at least one of the time-synchronized synchronization signals by a preestablished amount, and providing the preestablished amount of the time displacing to the step of obtaining, so that the preestablished amount of time displacement may be accounted for in the obtaining of the relative location of the subscriber device.

Claim 10

Dependent Claim 31 words

The process of claim 1, wherein the step of providing a subscriber device includes the step of providing a cellular digital data receiver operable with a Cellular Digital Packet Data format.

Claim 11

Dependent Claim 181 words

Apparatus for determining a location of a subscriber device in a wireless cellular communications system, comprising: at least three cellular cell site transmitters, each of the cellular cell site transmitters including means for providing a timing signal synchronized to a common time standard, the common time standard being a time standard that is the same for each of the cellular cell site transmitters, and means for transmitting a cellular digital data signal having a time-synchronized synchronization signal synchronized to the timing signal; a subscriber device having a cellular digital data receiver operable to receive the cellular digital data signal transmitted by the cellular cell site transmitters, means for determining a time of arrival of each of the time-synchronized synchronization signals relative to the internal clock; means for determining the location of the cellular cell site transmitters; and means for obtaining the location of the subscriber device from the locations of the cellular cell site transmitters and the time of arrival of the time-synchronized synchronization signal at each of the at least three cellular cell site transmitters relative to the internal clock.

Claim 12

Dependent Claim 181 words

Apparatus for determining a location of a subscriber device in a wireless cellular communications system, comprising: at least three cellular cell site transmitters, each of the cellular cell site transmitters including means for providing a timing signal synchronized to a common time standard, the common time standard being a time standard that is the same for each of the cellular cell site transmitters, and means for transmitting a cellular digital data signal having a time-synchronized synchronization signal synchronized to the timing signal; a subscriber device having a cellular digital data receiver operable to receive the cellular digital data signal transmitted by the cellular cell site transmitters, means for determining a time of arrival of each of the time-synchronized synchronization signals relative to the internal clock; means for determining the location of the cellular cell site transmitters; and means for obtaining the location of the subscriber device from the locations of the cellular cell site transmitters and the time of arrival of the time-synchronized synchronization signal at each of the at least three cellular cell site transmitters relative to the internal clock.

Claim 13

Dependent Claim 19 words

The apparatus of claim 10, wherein the means for providing a timing signal includes a global positioning system receiver.

Claim 14

Dependent Claim 52 words

The apparatus of claim 10, wherein the cellular digital data signal includes information defining the location of the cell site transmitters and the means for determining the location of the cell site transmitters includes means for decoding the data signals to obtain the information defining the location of the cell site transmitters.

Claim 15

Dependent Claim 65 words

The apparatus of claim 10, wherein the means for determining the time of arrival includes means for aligning the internal clock to a first one of the time-synchronized synchronization signals received at a first time, and establishing the arrival times of a second and a third later-received time-synchronized synchronization signals of respective second and third cellular cell site transmitters relative to the aligned internal clock.

Claim 16

Dependent Claim 16 words

The apparatus of claim 10, wherein the means for obtaining is located within the subscriber device.

Claim 17

Dependent Claim 20 words

The apparatus of claim 10, further including means for providing the location of the subscriber device to an external device.

Claim 18

Dependent Claim 43 words

The apparatus of claim 10, further including means for transmitting the relative time of arrival of each of the synchronized time-synchronized synchronization signals to a remote location, and wherein the means for obtaining is located at least in part at the remote location.

Claim 19

Dependent Claim 24 words

The apparatus of claim 10, wherein the means for transmitting includes means for providing time-synchronized synchronized signals having no intentionally introduced time displacements therein.

Claim 20

Dependent Claim 78 words

The apparatus of claim 10, wherein the means for transmitting further includes means for introducing a time displacement into at least one of the time-synchronized synchronization signals by a preestablished amount upon transmittal, and means for providing the preestablished amount of the time displacement to the means for obtaining, so that the time displacement may be accounted for in the obtaining of the location of the subscriber device relative to the locations of the cellular cell site transmitters.

Claim 21

Dependent Claim 20 words

The apparatus of claim 10, wherein the cellular digital data receiver is operable with a Cellular Digital Packet Data format.

Claim 22

Dependent Claim 138 words

Apparatus for determining a location of a subscriber device in a wireless cellular communications system, the apparatus comprising the subscriber device having a cellular digital data receiver operable to receive cellular digital data signals transmitted by at least three cellular cell site transmitters, each of the cellular digital data signals including a time-synchronized synchronization signal synchronized to a common time standard, the common time standard being a time standard that is the same for each of the cellular cell site transmitters,; an internal clock; means for determining a time of arrival of each of the time-synchronized synchronization signals relative to the internal clock; and means for obtaining the location of the subscriber device relative to the at least three cellular cell site transmitters from the times of arrival of the time-synchronized synchronization signals relative to the internal clock.

Claim 23

Dependent Claim 138 words

Apparatus for determining a location of a subscriber device in a wireless cellular communications system, the apparatus comprising the subscriber device having a cellular digital data receiver operable to receive cellular digital data signals transmitted by at least three cellular cell site transmitters, each of the cellular digital data signals including a time-synchronized synchronization signal synchronized to a common time standard, the common time standard being a time standard that is the same for each of the cellular cell site transmitters,; an internal clock; means for determining a time of arrival of each of the time-synchronized synchronization signals relative to the internal clock; and means for obtaining the location of the subscriber device relative to the at least three cellular cell site transmitters from the times of arrival of the time-synchronized synchronization signals relative to the internal clock.

Claim 24

Dependent Claim 45 words

The apparatus of claim 20, wherein the cellular digital data receiver includes a radio frequency receiver operable to receive cellular transmissions, a filter that eliminates noise from the received cellular transmissions, and a discriminator that produces a hard limited signal from the filtered cellular transmissions.

Claim 25

Dependent Claim 108 words

The apparatus of claim 20, wherein the means for determining the time of arrival includes means for aligning the internal clock with a correlation feature of a first one of the time-synchronized synchronization signals received by the cellular digital data receiver from a first cellular cell site transmitter, and means for establishing the time increment of receipt of the correlation feature of each of the time-synchronized synchronization signals received from a second and a third cellular cell site transmitter relative to the aligned internal clock, thereby establishing the relative time of receipt of the time-synchronized synchronization signals of the digital data signals relative to the common time standard.

Claim 26

Dependent Claim 60 words

The apparatus of claim 22, wherein the correlation feature is a common bit in each of the time-synchronized synchronization signals, and wherein the means for establishing includes means for dividing the bits of each of the second and third time-synchronized synchronization signals into fractional time increments and for establishing a fractional bit interval displacement for each of the common bits.

Claim 27

Dependent Claim 24 words

The apparatus of claim 23 wherein the correlation feature is a leading edge of the common bit in each of the time-synchronized synchronization signals.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2001-09-28	2002-03-30	2002-09-29	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2005-09-28	2006-03-30	2006-09-29	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2009-09-28	2010-03-30	2010-09-29	$7700.00	Window Closed / Lapsed

Method and apparatus for determining location of a subscriber device in a wireless cellular communications system

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