Asynchronous wireless communication system
First Claim
1. A method comprising:
- obtaining, by a device, an initial set of estimates of differences between base station timing offsets for a pair of base stations;
obtaining, by the device, measurements of a timing of first signals received by a wireless communication unit from the pair of base stations;
using, by the device, the measurements to derive a first location estimate of the wireless communication unit;
obtaining, by the device, a first current confidence score for the first location estimate;
estimating, by the device, a difference in first path lengths for second signals and a difference in second path lengths for third signals received, by the wireless communication unit, from at least one of;
another pair of base stations, oranother wireless communication unit;
determining, by the device and using the estimated difference in the first path lengths and the estimated difference in the second path lengths, a second location estimate of the wireless communication unit;
using, by the device, the second location estimate to create a revised, estimated difference in the first path lengths and a revised, estimated difference in the second path lengths;
using, by the device, the first location estimate, the revised, estimated difference in the first path lengths, and the revised, estimated difference in the second path lengths, to produce a revised set of estimates of differences;
weighting, by the device, the revised set of estimates of differences based on the first current confidence score and a second current confidence score,the second current confidence score being associated with the second location estimate; and
using, by the device, the weighted, revised set of estimates of differences to refine the initial set of estimates of differences.
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Abstract
The invention relates to an asynchronous wireless communication system, such as a UMTS system. The various base stations of an asynchronous wireless communication system do not typically have known timing offsets Tb(i), and these timing offsets vary with time. The invention allows the calculation of the difference dTb(i,j) between timing offsets Tb(i), Tb(j) for pairs of base stations B(i), B(j), using the timing of signals received by one or more wireless communication units. Having eliminated the timing offsets between the base stations as a variable, geo-location techniques from synchronous networks may then be used to locate wireless communication units in the asynchronous wireless communication system.
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Citations
20 Claims
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1. A method comprising:
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obtaining, by a device, an initial set of estimates of differences between base station timing offsets for a pair of base stations; obtaining, by the device, measurements of a timing of first signals received by a wireless communication unit from the pair of base stations; using, by the device, the measurements to derive a first location estimate of the wireless communication unit; obtaining, by the device, a first current confidence score for the first location estimate; estimating, by the device, a difference in first path lengths for second signals and a difference in second path lengths for third signals received, by the wireless communication unit, from at least one of; another pair of base stations, or another wireless communication unit; determining, by the device and using the estimated difference in the first path lengths and the estimated difference in the second path lengths, a second location estimate of the wireless communication unit; using, by the device, the second location estimate to create a revised, estimated difference in the first path lengths and a revised, estimated difference in the second path lengths; using, by the device, the first location estimate, the revised, estimated difference in the first path lengths, and the revised, estimated difference in the second path lengths, to produce a revised set of estimates of differences; weighting, by the device, the revised set of estimates of differences based on the first current confidence score and a second current confidence score, the second current confidence score being associated with the second location estimate; and using, by the device, the weighted, revised set of estimates of differences to refine the initial set of estimates of differences. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A non-transitory computer-readable medium storing instructions, the instructions comprising:
one or more instructions which, when executed by a processor, cause the processor to; obtain an initial set of estimates of differences between base station timing offsets for a pair of base stations in an asynchronous wireless communication system; obtain measurements of a timing of first signals received by a wireless communication unit from the pair of base stations; use the measurements to derive a first location estimate of the wireless communication unit; obtain first current confidence score for the first location estimate; estimate a difference in first path lengths for a second signal and a difference in second path lengths for third signals received, by the wireless communication unit, from at least one of; another pair of base stations, or another wireless communication unit; determine, using the estimated difference in the first path lengths and the estimated difference in the second path lengths, a second location estimate of the wireless communication unit use the second location estimate to create a revised, estimated difference in the first path lengths and a revised, estimated difference in the second path lengths; use the first location estimate, the revised, estimated difference in the first path lengths, and the revised, estimated difference in the second path lengths, to produce a revised set of estimates of differences; weight the revised set of estimates of differences based on the first current confidence score and a second current confidence score, the second current confidence score being associated with the second location estimate; and use the weighted, revised set of estimates of differences to refine the initial set of estimates of differences. - View Dependent Claims (12, 13, 14, 15)
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16. An asynchronous wireless communication system, comprising:
one or more devices to; obtain an initial set of estimates of differences between base station timing offsets for a pair of base stations in an asynchronous wireless communication system; obtain measurements of a timing of first signals received by a wireless communication unit from the pair of base stations; use the measurements to obtain a first location estimate of the wireless communication unit; obtain a first current confidence score for the first location estimate; estimate a difference in first path lengths for a second signal and a difference in second path lengths for third signals received, by the wireless communication unit, from at least one of; another pair of base stations, or another wireless communication unit; determine, using the estimated difference in the first path lengths and the estimated difference in the second path lengths, a second location estimate of the wireless communication unit; use the second location estimate to create a revised, estimated difference in the first path lengths and a revised, estimated difference in the second path lengths; use first location estimate, the revised, estimated difference in the first path lengths, and the revised, estimated difference in the second path lengths, to produce a revised set of estimates of differences; and weight the revised set of estimates of differences based on the first current confidence score and a second current confidence score, the second current confidence score being associated with the second location estimate, and the weighted, revised set of estimates of differences being used to refine the initial set of estimates of differences. - View Dependent Claims (17, 18, 19, 20)
Specification