Position computation in a positioning system using synchronization time bias
First Claim
1. A method of determining position, the method comprising:
- receiving signals from a satellite navigation system;
receiving signals from a wireless communication system; and
obtaining a synchronization bias constraint that defines a limit of a difference between a system time of the wireless communication system and a system time of the satellite navigation system; and
determining a position solution for a mobile unit in an asynchronous environment as a function of the received signals, the synchronization bias constraint, and a number of independent measurements based on a position location technique for a synchronous environment, wherein the number of independent measurements is fewer than a minimum number of measurements for a position location technique in the asynchronous environment.
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Abstract
In general, this disclosure is directed to techniques for computing a positioning solution for a mobile unit based on signals received from the satellite navigation system and the wireless communication system. The techniques allow for, and resolve, a synchronization bias that constrains a system time for the satellite navigation system and a system time for the wireless communication system relative to each other. The mobile unit may utilize the defined constraint to compute a position solution in environments where additional independent measurements would otherwise be required. The mobile unit may incorporate Receiver Autonomous Integrity Monitoring (RAIM) functionality to validate the position and time solutions derived from each of received signals. According to the techniques described herein, the mobile unit may be able to utilize the defined synchronization bias to apply RAIM or similar techniques in environments where such techniques would otherwise be indeterminate.
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Citations
31 Claims
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1. A method of determining position, the method comprising:
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receiving signals from a satellite navigation system; receiving signals from a wireless communication system; and obtaining a synchronization bias constraint that defines a limit of a difference between a system time of the wireless communication system and a system time of the satellite navigation system; and determining a position solution for a mobile unit in an asynchronous environment as a function of the received signals, the synchronization bias constraint, and a number of independent measurements based on a position location technique for a synchronous environment, wherein the number of independent measurements is fewer than a minimum number of measurements for a position location technique in the asynchronous environment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17)
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14. The method of clan 1, wherein determining the position solution for the mobile unit comprises determining the position solution based on Advanced Forward Link Trilateration.
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18. A method of determining position, the method comprising:
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determining a first number of independent positioning measurement based on signals from a satellite navigation system; determining a second number of independent positioning measurements based on signals from a wireless communication system; determining a synchronization bias constraint that constrains a system time of the wireless communication system in relation to a system time of the satellite navigation system; identifying presence of redundant measurements based on a minimum number of measurements for a position location technique in a synchronous environment and the synchronization bias constraint; applying Receiver Autonomous Integrity Monitoring (RAIM) to detect the presence of one or more erroneous measurements based on redundant measurements; isolating erroneous measurements; and determining a position solution for a mobile unit based on a hybrid position location technique in an asynchronous environment, and as a function of the independent positioning measurements, the synchronization bias constraint, a number of independent measurements at least equal to a minimum number of measurements for a position location technique in a synchronous environment, and excluding the isolated erroneous measurements, wherein the minimum number of independent measurements in the synchronous environment is fewer than a minimum number of measurements for a position location technique in the asynchronous environment.
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19. An apparatus for determining position, the apparatus comprising:
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a Satellite Positioning System (SPS) receiver configured to receive signals from a satellite positioning system; a wireless communication system receiver configured to receive signals from a wireless communication system and further configured to receive a synchronization bias constraint that defines a limit of a difference between a system time of the wireless communication system and a system time of the satellite positioning system; and a processor configured to determine a position solution for a mobile unit in an asynchronous environment as a function of the received signals, the synchronization bias constraint, and a number of independent measurements based on a position location technique for a synchronous environment, wherein the number of independent measurements is fewer than a minimum number of measurements for a position location technique in the asynchronous environment. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. An apparatus for determining position, the apparatus comprising:
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means for receiving signals from a satellite navigation system; means for receiving signals from a wireless communication system; means for obtaining a synchronization bias constraint that defines a limit of a difference between a system time of the wireless communication system and a system time of the satellite navigation system; and means for determining a position solution for a mobile unit in an asynchronous environment as a function of the received signals, the synchronization bias constraint, and a number of independent measurements based on a position location technique for a synchronous environment, wherein the number of independent measurements is fewer than a minimum number of measurements for a position location technique in the asynchronous environment. - View Dependent Claims (28, 29, 30)
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31. A non-transitory, computer-readable medium encoded with one or more instructions, when executed by a computer, determining position, the instructions comprising:
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instructions for receiving signals from a satellite navigation system; instructions for receiving signals from a wireless communication system; instructions for obtaining a synchronization bias constraint that defines a limit of a difference between a system time of the wireless communication system and a system time of the satellite navigation system; and instructions for determining a position solution for a mobile unit in an asynchronous environment as a function of the received signals, the synchronization bias constraint, and a number of independent measurements based on a position location technique for a synchronous environment, wherein the number of independent measurements is fewer than a minimum number of measurements for a position location technique in the asynchronous environment.
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Specification