Efficient use of expected user altitude data to aid in determining a position of a mobile station
First Claim
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1. A method for computing a position of a mobile station, the method comprising:
- storing at least one predetermined portion of an expected user altitude database in the mobile station;
accessing a global elevation estimate;
estimating an initial position of the mobile station based on the global elevation estimate and at least three global positioning system satellite measurements;
identifying a first selected area in the stored at least one predetermined portion of the expected user altitude database based on the estimated initial position, the first selected area based on and including the estimated initial position;
determining an altitude estimate from the initial position of the mobile station, and the at least one predetermined portion of the expected user altitude database, wherein the expected user altitude database includes at least two assumed altitude levels for the mobile station associated with at least a subset of coverage areas included in the expected user altitude database, and wherein determining the altitude estimate for the subset of coverage areas includes selecting an assumed altitude level from the at least two assumed altitude levels based at least in part on the velocity of the mobile station; and
calculating the position of the mobile station.
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Abstract
A method and apparatus for using a predetermined portion of terrain elevation maps in a database for aiding in computing a three-dimensional position of a wireless station. Instead of using the entire terrain model of the earth or an entire country, the database consists of an incomplete model, which includes only the most populous areas or specific regions. This reduces the size of the information in the database, which in turn reduces the amount of time to compute the positions of the wireless device.
18 Citations
26 Claims
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1. A method for computing a position of a mobile station, the method comprising:
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storing at least one predetermined portion of an expected user altitude database in the mobile station; accessing a global elevation estimate; estimating an initial position of the mobile station based on the global elevation estimate and at least three global positioning system satellite measurements; identifying a first selected area in the stored at least one predetermined portion of the expected user altitude database based on the estimated initial position, the first selected area based on and including the estimated initial position; determining an altitude estimate from the initial position of the mobile station, and the at least one predetermined portion of the expected user altitude database, wherein the expected user altitude database includes at least two assumed altitude levels for the mobile station associated with at least a subset of coverage areas included in the expected user altitude database, and wherein determining the altitude estimate for the subset of coverage areas includes selecting an assumed altitude level from the at least two assumed altitude levels based at least in part on the velocity of the mobile station; and calculating the position of the mobile station. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 21, 22, 23, 24, 25, 26)
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10. A system for computing a position of a mobile station, the system comprising:
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means for storing at least one predetermined portion of an expected user altitude database in the mobile station; means for accessing a global elevation estimate; means for estimating an initial position of the mobile station based on the global elevation estimate and at least three global positioning system satellites; means for identifying a first selected area in the stored at least one predetermined portion of the expected user altitude database based on the estimated initial position, the first selected area based on and including the estimated initial position; means for determining an altitude estimate from the initial position of the mobile station, and the at least one predetermined portion of the expected user altitude database, wherein the expected user altitude database includes at least two assumed altitude levels for the mobile station associated with at least a subset of coverage areas included in the expected user altitude database, and wherein determining the altitude estimate for the subset of coverage areas includes selecting an assumed altitude level from the at least two assumed altitude levels based at least in part on the velocity of the mobile station; and means for calculating the position of the mobile station. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A computer program product, comprising:
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a non-transitory computer readable medium comprising; code for causing a location of a mobile station to be computed, the computer code comprising; code for causing at least one predetermined portion of an expected user altitude database to be stored in the mobile station; code for causing a global elevation to be estimated; code for causing an initial position of the mobile station to be made based on the global elevation estimate and at least three global positioning system satellites; code for causing a first selected area in the stored at least one predetermined portion to be selected based on the estimated initial position, the first selected area based on and including the estimated initial position; code for determining an altitude estimate from the initial position of the mobile station, and at least one predetermined portion of an expected user altitude database, wherein the expected user altitude database includes at least two assumed altitude levels for the mobile station associated with at least a subset of coverage areas included in the expected user altitude database, and wherein determining the altitude estimate for the subset of coverage areas includes selecting an assumed altitude level from the at least two assumed altitude levels based at least in part on the velocity of the mobile station; and code for causing the position of the mobile station to be calculated. - View Dependent Claims (18, 19)
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20. A mobile station comprising:
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a GPS computer to; compute a position of the mobile station; access a global elevation estimate; estimate an initial position of the mobile station based on the global elevation estimate and at least three global positioning system satellite measurements; identify a first selected area in the stored at least one predetermined portion of the expected user altitude database based on the estimated initial position, the first selected area based on and including the estimated initial position; determine an altitude estimate from the initial position of the mobile station, and at least one predetermined portion of an expected user altitude database, wherein the expected user altitude database includes at least two assumed altitude levels for the mobile station associated with at least a subset of coverage areas included in the expected user altitude database, and wherein determining the altitude estimate for the subset of coverage areas includes selecting an assumed altitude level from the at least two assumed altitude levels based at least in part on the velocity of the mobile station; and calculate the position of the mobile station; and a memory to store the at least one predetermined portion of the expected user altitude database in the mobile station.
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Specification