Reliability and the accuracy of position-finding methods by estimation of the rice factor of a radio link
First Claim
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1. A method for determination of the quality of a radio link, in which the radio signals propagate via two or more propagation paths, comprising:
- estimating a parameter that is characteristic of a signal strength of a received signal that is transmitted via a line-of-sight path, with respect to a strength of received signals transmitted via non-line-of-sight paths; and
assuming a Rice distribution as the distribution function for the signal strength amplitude, wherein the estimated parameter comprises a Rice factor (K), and wherein the Rice factor is estimated using;
where R is the amplitude of the sample values of the received signal and Ê
{x} is approximated by a running averaging of x.
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Abstract
In order to improve the reliability and the accuracy of a position-finding method such as the GPS method, the quality of a radio link which is used for the position-finding method is determined by estimating a parameter, in particular the Rice factor of the amplitude distribution density, which is characteristic of the ratio of the strength of a signal transmitted via a line-of-sight path, with respect to the strength of the signals transmitted via non-line-of-sight paths.
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Citations
11 Claims
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1. A method for determination of the quality of a radio link, in which the radio signals propagate via two or more propagation paths, comprising:
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estimating a parameter that is characteristic of a signal strength of a received signal that is transmitted via a line-of-sight path, with respect to a strength of received signals transmitted via non-line-of-sight paths; and
assuming a Rice distribution as the distribution function for the signal strength amplitude, wherein the estimated parameter comprises a Rice factor (K), and wherein the Rice factor is estimated using;
where R is the amplitude of the sample values of the received signal and Ê
{x} is approximated by a running averaging of x.
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2. A method for determination of the quality of a radio link, in which the radio signals propagate via two or more propagation paths, comprising:
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estimating a parameter that is characteristic of a signal strength of a received signal that is transmitted via a line-of-sight path, with respect to a strength of received signals transmitted via non-line-of-sight paths; and
assuming a Rice distribution as the distribution function for the signal strength amplitude, wherein the estimated parameter comprises a Rice factor (K), and wherein the Rice factor is estimated using;
where R is the amplitude of the sample values of the received signal and Ê
{x} is approximated by a running averaging of x.
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3. A method for finding the position of a mobile station by means of a radio link between the mobile station and at least one reference station, comprising:
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determining a quality of the radio link, wherein the quality determination comprises estimating a parameter that is characteristic of a signal strength of a received signal that is transmitted via a line-of-sight path, with respect to a strength of received signals transmitted via non-line-of-sight paths; and
using the parameter to decide whether the signal received from the reference station is to be used for position finding;
orusing the signals associated with the line-of-sight path and non line-of-sight paths for position finding after assigning weights to each of the signals by means of a weighting factor based on the value of the parameter for each of the signals. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for generating an estimated Rice factor for use in ascertaining the quality of a radio link, comprising:
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a magnitude squaring device comprising an input configured to receive amplitude values of sampled received signals;
a first squaring device comprising an input connected to an output of the magnitude squaring device;
a first running averaging device comprising an input connected to an output of the first magnitude squaring device;
a second running averaging device comprising an input connected to an output of the first squaring device;
a second squaring device comprising an input connected to an output of the first running averaging device;
a first adder comprising a first input connected to an output of the second squaring device, and a second input connected to an output of the second running averaging device with its mathematical sign being reversed;
a times-two multiplier comprising an input connected to the output of the second squaring device;
a second adder comprising a first input connected to an output of the times-two multiplier, and a second input connected to the output of the second running averaging device with its mathematical sign being reversed;
a square-rooting device comprising an input connected to an the output of the second adder;
a multiplier comprising a first input connected to the output of the first running averaging device, and a second input connected to an output of the square-rooting device;
a third adder comprising a first input connected to the output of the times-two multiplier with its mathematical sign being reversed, a second input connected to an output of the multiplier with its mathematical sign being reversed, and a third input connected to the output of the second running averaging device; and
a combined multiplier/divider comprising a multiplier or numerator input connected to an output of the third adder, and a divider or denominator input connected to an output of the second adder, and configured to produce the estimated Rice factor at its output.
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Specification