Radio Mobile Unit Location System
First Claim
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1. A method of determining a Real Time Difference (RTD) between respective clocks of a first network element and a second network element in a communications network, the method comprising:
- measuring at least one parameter resulting from a first handover of a first mobile unit from the first network element to the second network element to provide a first measurement set;
measuring the at least one parameter resulting from a handover of at least one further mobile unit between the first network element and the second network element to provide a further measurement set; and
processing the first and further measurement sets to provide an estimate of a common RTD.
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Abstract
Disclosed is a method for locating a mobile radio unit within a mobile radio communications network. The method provides for the calculation of network variables such as a Real Time Difference (RTD) between network elements, from measurements already available to the network from, for example, handovers between network elements. The method provides for the location of radio mobile units without having to synchronise network elements such as BTSs or LMUs.
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Citations
30 Claims
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1. A method of determining a Real Time Difference (RTD) between respective clocks of a first network element and a second network element in a communications network, the method comprising:
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measuring at least one parameter resulting from a first handover of a first mobile unit from the first network element to the second network element to provide a first measurement set; measuring the at least one parameter resulting from a handover of at least one further mobile unit between the first network element and the second network element to provide a further measurement set; and processing the first and further measurement sets to provide an estimate of a common RTD. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of averaging a plurality of RTD measurements taken in respect of a communications network clocked element which experiences clock drift, the method comprising:
averaging the plurality of RTD measurements over a given period of time. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A method of calculating a real time difference (RTD) between respective clocks of a first network element and a second network element within a radio communications network, the method comprising;
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estimating a position of a mobile element within the network to provide an estimated mobile element position; calculating a distance (d1) between the first network element and the estimated mobile element position; calculating a distance (d2) between the second network element and the estimated mobile element position; measuring an Observed Time Difference (OTD1,2) between the respective clocks of the first and second network elements; and calculating the RTD according to the following formula;
RTD1,2=OTD1,2−
d1 d2 - View Dependent Claims (22, 23, 24)
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25. A method of calculating a Real Time Difference (RTD) between respective clocks of a first network element and a second network element within a radio communications network, the method including;
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estimating a position of a mobile element handing over from the first network element to the second network element, using a current value of the RTD found by the network; estimating a subsequent RTD using the estimated position of the mobile element; processing the subsequent RTD according to the first aspect of the present invention and using the processed subsequent RTD to again estimate the position of the mobile element; and repeating the process for as many cycles as is required. - View Dependent Claims (26)
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27. A method for determining a position of a mobile unit within a mobile radio communications network, the method including the use of an Observed Time Difference (OTD) in conjunction with two or more time of arrivals (TA) and a current RTD held by the network to derive a Geometric Time Difference (GTD) describing a hyperbolic locus of position.
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28. A method of estimating a position of a mobile unit between two network elements within a radio communications network, the method including:
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measuring signal strength at the mobile unit to provide a first measurement; obtaining a Timing Advance measurement at the mobile unit to provide a second measurement; measuring an Observed Time Difference (OTD) between the two network elements at the mobile unit to provide a third measurement; and combining and processing the three measurements to obtain an estimate of the position of the mobile unit. - View Dependent Claims (29, 30)
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Specification