Method and apparatus for locating a mobile station in a spread spectrum communication system
First Claim
1. A method for locating a mobile station in a spread spectrum communication system, the method comprising the steps of:
- transmitting a first signal comprising a plurality of transmitted symbols from a first base station to the mobile station;
receiving by the first base station from the mobile station a second signal comprising a first plurality of received symbols in response to the first signal;
demodulating the second signal by the first base station to form a demodulated signal;
reencoding at least a portion of the demodulated signal by the first base station to form a reference signal;
receiving the reference signal by a second base station;
receiving by the first base station and the second base station a retransmitted second signal comprising a second plurality of received symbols from the mobile station, the retransmitted second signal in response to a retransmitted first signal comprising a plurality of retransmitted symbols directed to the mobile station;
comparing, by the first base station, the retransmitted second signal with the reference signal at a first time and at a second time;
comparing, by the second base station, the retransmitted second signal with the reference signal at the first time and at the second time;
based on the comparisons at the first base station, determining a first delay of the retransmitted second signal, the first delay representing a travel time of the retransmitted second signal from the mobile station to the first base station;
based on the comparisons at the second base station, determining a second delay of the retransmitted second signal, the second delay representing a travel time of the retransmitted second signal from the mobile station to the second base station; and
based on the first and second delays, determining a location of the mobile station.
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Accused Products
Abstract
The method includes receiving (404) by a first base station (212) a signal (215) transmitted from the mobile station (216); demodulating (406) the signal by the first base station (212) to form a demodulated signal; remodulating (408) at least a portion of the demodulated signal to form a reference signal; receiving (412) by the first base station (212) and a second base station (210, 214) a retransmitted signal (217); comparing (414, 16), by the first base station (212), the retransmitted signal (217) with the reference signal to determine a first delay; comparing (414, 416), by the second base station (210, 214), the retransmitted second signal (217) with the reference signal to determine a second delay; and based on the first and second delays, determining (420) a location of the mobile station (216).
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Citations
20 Claims
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1. A method for locating a mobile station in a spread spectrum communication system, the method comprising the steps of:
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transmitting a first signal comprising a plurality of transmitted symbols from a first base station to the mobile station; receiving by the first base station from the mobile station a second signal comprising a first plurality of received symbols in response to the first signal; demodulating the second signal by the first base station to form a demodulated signal; reencoding at least a portion of the demodulated signal by the first base station to form a reference signal; receiving the reference signal by a second base station; receiving by the first base station and the second base station a retransmitted second signal comprising a second plurality of received symbols from the mobile station, the retransmitted second signal in response to a retransmitted first signal comprising a plurality of retransmitted symbols directed to the mobile station; comparing, by the first base station, the retransmitted second signal with the reference signal at a first time and at a second time; comparing, by the second base station, the retransmitted second signal with the reference signal at the first time and at the second time; based on the comparisons at the first base station, determining a first delay of the retransmitted second signal, the first delay representing a travel time of the retransmitted second signal from the mobile station to the first base station; based on the comparisons at the second base station, determining a second delay of the retransmitted second signal, the second delay representing a travel time of the retransmitted second signal from the mobile station to the second base station; and based on the first and second delays, determining a location of the mobile station. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for locating a mobile station in a spread spectrum communication system, the method comprising the steps of:
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receiving by a first base station a signal transmitted from the mobile station; demodulating the signal by the first base station to form a demodulated signal; remodulating at least a portion of the demodulated signal to form a reference signal; receiving by the first base station and a second base station a retransmitted signal; comparing, by the first base station, the retransmitted signal with the reference signal to determine a first delay; comparing, by the second base station, the retransmitted second signal with the reference signal to determine a second delay; and based on the first and second delays, determining a location of the mobile station.
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19. An apparatus for locating a mobile station in a spread spectrum communication system, the apparatus comprising:
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a first base station responsive to the mobile station, the first base station comprising; a first antenna transmitting a first signal to the mobile station, the first antenna receiving a second signal from the mobile station in response to the first signal; a first demodulator responsive to the second signal, producing a demodulated signal; a reencoder responsive to the demodulated signal, forming a reference signal; a first correlator, comparing the reference signal to a retransmitted second signal received by the first antenna to determine a first delay, the first delay representing a travel time of the retransmitted second signal from the mobile station to the first base station; a second base station responsive to the mobile station and the reference signal, the second base station comprising; a second antenna receiving the retransmitted second signal from the mobile station and receiving the reference signal; a second correlator, comparing the reference signal to the retransmitted second signal to determine a second delay, the second delay representing a travel time of the retransmitted second signal from the mobile station to the second base station; and a controller responsive to the first and second base stations, the controller determining a location of the mobile station based on the first delay and the second delay.
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20. A method for locating a mobile station in a spread spectrum communication system, the method comprising the steps of:
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receiving by a first base station a signal transmitted by the mobile station, the signal comprising a received frame, the received frame having a plurality of received symbols; storing the signal by the first base station in a first memory; receiving the signal by a second base station; storing the signal by the second base station in a second memory; demodulating the received frame by the first base station to form a demodulated frame; receiving the demodulated frame by the second base station; at the first base station, reencoding the demodulated frame to form a reencoded frame, the reencoded frame having a plurality of encoded symbols; at the second base station, reencoding the demodulated frame to form the reencoded frame; at the first base station, comparing at a first plurality of times each of the plurality of received symbols in the first memory with each of the plurality of reencoded symbols; based on the comparisons at the first plurality of times, determining a first delay representing a travel time of the signal from the mobile station to the first base station; at the second base station, comparing at a second plurality of times each of the plurality of received symbols in the second memory with each of the plurality of reencoded symbols; based on the comparisons at the second plurality of times, determining a second delay representing a travel time of the signal from the mobile station to the second base station; and based on the first and second delays, determining a location of the mobile station.
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Specification