GPS synchronization for wireless communications stations
First Claim
1. A method for determining a GPS-synchronized timing representation for downlink signals transmitted from a base transceiver station (BTS) of a wireless communications system (WCS), comprising:
- (a) receiving, at a measurement unit, a downlink signal transmitted by said BTS;
(b) evaluating said downlink signal to determine a time of arrival (TOA) at said measurement unit of a specified portion of said downlink signal; and
(c) determining an optimal time value for a GPS-based transmission time of an identifiable instant related to said measured TOA.
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Accused Products
Abstract
A method and system are specified to determine, provide, and exploit the precise time base relations between the distinct signal timings of the Global Positioning System (GPS) and a wireless communications system (WCS) for which the internal WCS downlink time base standards are not inherently synchronized to GPS timing. These downlink signal synchronization facilities are particularly beneficial for a wireless location system (WLS) and related methods and subsystems that provide mobile-station location determination through the exploitation of the time base synchronization information, e.g., to assist a GPS-equipped mobile station in determining its GPS-derived measurements with enhanced efficiency and accuracy.
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Citations
32 Claims
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1. A method for determining a GPS-synchronized timing representation for downlink signals transmitted from a base transceiver station (BTS) of a wireless communications system (WCS), comprising:
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(a) receiving, at a measurement unit, a downlink signal transmitted by said BTS;
(b) evaluating said downlink signal to determine a time of arrival (TOA) at said measurement unit of a specified portion of said downlink signal; and
(c) determining an optimal time value for a GPS-based transmission time of an identifiable instant related to said measured TOA. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A computer readable medium comprising instructions for instructing a processor to perform a set of steps to determine a GPS-synchronized timing representation for downlink signals transmitted from a base transceiver station (BTS) of a wireless communications system (WCS), said set of steps comprising:
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(a) receiving a downlink signal transmitted by said BTS;
(b) evaluating said downlink signal to determine a time of arrival (TOA) of a specified portion of said downlink signal; and
(c) determining an optimal time value for a GPS-based transmission time of an identifiable instant related to said measured TOA. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A wireless system, including a location measuring unit (LMU) and at least one base transceiver station (BTS) for communicating with at least one mobile station (MS), said LMU including a GPS receiver and a receiver for receiving downlink signals transmitted by said BTS, and a processor configured to control said LMU in performing a set of steps to determine a GPS-synchronized timing representation for downlink signals transmitted from said BTS, said set of steps comprising:
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(a) receiving a downlink signal transmitted by said BTS;
(b) evaluating said downlink signal to determine a time of arrival (TOA) of a specified portion of said downlink signal; and
(c) determining an optimal time value for a GPS-based transmission time of an identifiable instant related to said measured TOA. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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28. A signal processing method for use in processing a base transceiver station (BTS) downlink signal, comprising:
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(a) acquiring a candidate time series from a received BTS downlink burst signal;
(b) correlating a frequency correction channel (FCCH) replica with a candidate broadcast control channel (BCCH) beacon signal to determine a nominal frame time alignment and time of arrival (TOA) for an FCCH burst signal;
(c) correlating a synchronization channel (SCH) extended training sequence to determine a time alignment and TOA for an SCH burst signal; and
(d) attempting to demodulate the SCH burst signal. - View Dependent Claims (29, 30, 31, 32)
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Specification