Methods and Apparatus for Accurately Determining Signal Time of Arrival
First Claim
1. A method for determining the time of arrival of a signal at a mobile communication device, comprising:
- (a) correlating a received signal in a receiver in accordance with a correlation function to produce a stream of correlation samples including a peak sample, a plurality of pre-peak samples, and a plurality of post-peak samples, wherein the time of arrival of the signal corresponds to a timing of a peak of the correlation function, which lies in a vicinity of the peak sample;
(b) storing a curve matching table comprising a plurality of sets of values, each of the sets of values representing discrete points of a correlation function having a peak at a respective different time shift relative to the timing of the peak sample, wherein the plurality of sets of values includes first sets of values to be matched with a first set of samples from the stream of correlation samples and second sets of values to be matched with a second set of samples from the stream of correlation samples;
(c) matching each of the first sets of values to the first set of samples, the first set of samples including no post-peak samples;
(d) matching each of the second sets of values to the second set of samples, the second set of samples including at least one post-peak sample, wherein one set of values among the first and second sets of values produces a best match; and
(e) determining the time of arrival of the signal based on timing of the peak of the correlation function represented by the one set of values that produced the best match.
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Abstract
A technique for determining the time of arrival of a signal involves correlating a received signal with a correlation function to produce a stream of correlation samples including a peak sample, pre-peak samples, and post-peak samples. A curve matching table includes sets of values, where each set of values represents discrete points of a correlation function having a peak at a respective different time shift relative to the timing of the peak sample. The sets of values include first sets of values that are matched with a first set of samples having no post-peak samples from the correlation samples, and second sets of values that are matched with a second set of samples having at least one post-peak sample. The time of arrival of the signal is determined from the timing of the peak of the correlation function represented by the set of values that produces the best match.
18 Citations
20 Claims
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1. A method for determining the time of arrival of a signal at a mobile communication device, comprising:
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(a) correlating a received signal in a receiver in accordance with a correlation function to produce a stream of correlation samples including a peak sample, a plurality of pre-peak samples, and a plurality of post-peak samples, wherein the time of arrival of the signal corresponds to a timing of a peak of the correlation function, which lies in a vicinity of the peak sample; (b) storing a curve matching table comprising a plurality of sets of values, each of the sets of values representing discrete points of a correlation function having a peak at a respective different time shift relative to the timing of the peak sample, wherein the plurality of sets of values includes first sets of values to be matched with a first set of samples from the stream of correlation samples and second sets of values to be matched with a second set of samples from the stream of correlation samples; (c) matching each of the first sets of values to the first set of samples, the first set of samples including no post-peak samples; (d) matching each of the second sets of values to the second set of samples, the second set of samples including at least one post-peak sample, wherein one set of values among the first and second sets of values produces a best match; and (e) determining the time of arrival of the signal based on timing of the peak of the correlation function represented by the one set of values that produced the best match. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A mobile communication device, comprising:
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a receiver configured to receive a signal in accordance with a correlation function to produce a stream of correlation samples including a peak sample, a plurality of pre-peak samples, and a plurality of post-peak samples, wherein the time of arrival of the signal corresponds to a timing of a peak of the correlation function, which lies in a vicinity of the peak sample; a storage device configured to store a curve matching table comprising a plurality of sets of values, each of the sets of values representing discrete points of a correlation function having a peak at a respective different time shift relative to the timing of the peak sample, wherein the plurality of sets of values includes first sets of values to be matched with a first set of samples from the stream of correlation samples and second sets of values to be matched with a second set of samples from the stream of correlation samples; a processor configured to;
match each of the first sets of values to the first set of samples, the first set of samples including no post-peak samples;
match each of the second sets of values to the second set of samples, the second set of samples including at least one post-peak sample, wherein one set of values among the first and second sets of values produces a best match; and
determine the time of arrival of the signal based on a timing of the peak of the correlation function represented by the one set of values that produced the best match. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A computer readable medium storing instructions, that when executed by a computer, cause the computer to perform functions of:
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receiving a stream of correlation samples resulting from correlating a received signal in accordance with a correlation function, the correlation samples including a peak sample, a plurality of pre-peak samples, and a plurality of post-peak samples, wherein the time of arrival of a signal corresponds to a timing of a peak of the correlation function, which lies in a vicinity of the peak sample; retrieving data from a curve matching table comprising a plurality of sets of values, each of the sets of values representing discrete points of a correlation function having a peak at a respective different time shift relative to the timing of the peak sample, wherein the plurality of sets of values includes first sets of values to be matched with a first set of samples from the stream of correlation samples and second sets of values to be matched with a second set of samples from the stream of correlation samples; matching each of the first sets of values to the first set of samples, the first set of samples including no post-peak samples; matching each of the second sets of values to the second set of samples, the second set of samples including at least one post-peak sample, wherein one set of values among the first and second sets of values produces a best match; and determining the time of arrival of the signal based on timing of the peak of the correlation function represented by the one set of values that produced the best match.
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Specification