US5228057A
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US
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Method of determining sampling time points
Assignee: Telefonaktiebolaget LM Ericsson AB
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Filing: 1992-11-17
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Granted: 1993-07-13
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Expires: 2012-11-17
Abstract
Abstract Symbol sequences having synchronization sequences are transmitted over a radio channel. Received signals are sampled in signal sampling time points (n) and by correlation a channel response (C 2 ) is obtained. The impulse response is sampled (T s ) over a period (M×N) corresponding to time dispersion of the channel. For separate samples with separate start points (n), channel estimates are obtained (n=0, 2, 4, 6, N=1, 3, 5, 7. . .) whose energy values are calculated, and the estimate (n=8, 10, 12, 14) with the largest energy is selected. The first time point (n=8) in this estimate is selected as sampling time point for the symbol sequence. Alternatively, the signal sampling time point (n=9) with maximum energy value (C 2 max) is selected. By comparing the energy values either one of these signal sampling time points (n=8 , n=9) can be selected as the sampling time point for the symbol sequence. For consecutive sequences, an average value for the sampling time points is calculated.
Inventors
- 👤 Lars G. Larsson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 00:30
CPC Classifications
H; H04; H04L; H04L7/00; H04L7/0054; H04L7/04
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
178 words
A signal processing method comprising the steps of: sampling an analog signal at recurrent signal sampling time points which are selected relative to a synchronization time point common to a transmitter and a receiver, such that a time interval for transmission of a symbol comprises a whole number of signal sampling time points; correlating known synchronization sequences with sampled values generated by said sampling step to generate correlation values; determining energy values related to said correlation values; down sampling said energy values at a desired number of the signal sampling points which are mutually spaced apart by the time interval; calculating at least one comparison value based on said down sampled energy values and corresponding to at least one sampling signal time point; selecting one of the at least one comparison values having a largest magnitude; selecting one of the signal sampling time points which correspond to the selected largest comparison value as a reference sampling time point for one of said known synchronization sequences; and using said reference sampling time point to further process said analog signal.
Claim 2
Dependent Claim
178 words
A signal processing method comprising the steps of: sampling an analog signal at recurrent signal sampling time points which are selected relative to a synchronization time point common to a transmitter and a receiver, such that a time interval for transmission of a symbol comprises a whole number of signal sampling time points; correlating known synchronization sequences with sampled values generated by said sampling step to generate correlation values; determining energy values related to said correlation values; down sampling said energy values at a desired number of the signal sampling points which are mutually spaced apart by the time interval; calculating at least one comparison value based on said down sampled energy values and corresponding to at least one sampling signal time point; selecting one of the at least one comparison values having a largest magnitude; selecting one of the signal sampling time points which correspond to the selected largest comparison value as a reference sampling time point for one of said known synchronization sequences; and using said reference sampling time point to further process said analog signal.
Claim 3
Dependent Claim
30 words
The method of claim 1 wherein said step of using said reference sampling time point further comprises the step of: equalizing said analog signal using said reference sampling time point.
Claim 4
Dependent Claim
45 words
The method of claim 1 wherein said step of calculating further comprises the step of: summing energy values that are time indexed beginning at a predetermined symbol sampling time point, ending at a second predetermined symbol sampling time point and separated by said time interval.
Claim 5
Dependent Claim
38 words
The method of claim 3 further comprising the steps of: selecting the reference sampling time point for each subsequently received synchronization sequence; and iteratively averaging the reference sampling time points to obtain an estimated reference sampling time point.
Claim 6
Dependent Claim
53 words
The method of claim 4 wherein said step of iteratively averaging further includes the step of: applying a weighting function to the latest selected reference sampling time point corresponding to the latest incoming synchronization sequence, said weighting function assuming a zero value when the selected comparison value is beneath a predetermined threshold value.
Claim 7
Dependent Claim
233 words
A signal processing method comprising the steps of: sampling an analog signal at recurrent signal sampling time points which are selected relative to a synchronization time point common to a transmitter and a receiver, such that a time interval for transmission of a symbol comprises a whole number of signal sampling time points; correlating known synchronization sequences with sampled values generated by said sampling step to generate correlation values; determining energy values related to said correlation values; selecting an energy value having a largest magnitude; multiplying said energy value having the largest magnitude by a predetermined constant to determine a first comparison value; down sampling said energy values at a desired number of the signal sampling points that are mutually spaced apart by the time interval; calculating at least one second comparison value based on said down sampled energy values and corresponding to at least one sampling signal time point; selecting one of the at least one second comparison values having a largest magnitude; comparing said first comparison value with said selected at least one second comparison value; selecting a signal sampling time point, which corresponds to one of the first comparison value and the selected at least one second comparison value, based on said comparing step as a reference sampling time point for one of said known synchronization sequences; and using said reference sampling time point to further process said analog signal.
Claim 8
Dependent Claim
233 words
A signal processing method comprising the steps of: sampling an analog signal at recurrent signal sampling time points which are selected relative to a synchronization time point common to a transmitter and a receiver, such that a time interval for transmission of a symbol comprises a whole number of signal sampling time points; correlating known synchronization sequences with sampled values generated by said sampling step to generate correlation values; determining energy values related to said correlation values; selecting an energy value having a largest magnitude; multiplying said energy value having the largest magnitude by a predetermined constant to determine a first comparison value; down sampling said energy values at a desired number of the signal sampling points that are mutually spaced apart by the time interval; calculating at least one second comparison value based on said down sampled energy values and corresponding to at least one sampling signal time point; selecting one of the at least one second comparison values having a largest magnitude; comparing said first comparison value with said selected at least one second comparison value; selecting a signal sampling time point, which corresponds to one of the first comparison value and the selected at least one second comparison value, based on said comparing step as a reference sampling time point for one of said known synchronization sequences; and using said reference sampling time point to further process said analog signal.
Claim 9
Dependent Claim
30 words
The method of claim 6 wherein said step of using said reference sampling time point further comprises the step of: equalizing said analog signal using said reference sampling time point.
Claim 10
Dependent Claim
45 words
The method of claim 6 wherein said step of calculating further comprises the step of: summing energy values that are time indexed beginning at a predetermined symbol sampling time point, ending at a second predetermined symbol sampling time point and separated by said time interval.
Claim 11
Dependent Claim
38 words
The method of claim 8 further comprising the steps of: selecting the reference sampling time point for each subsequently received synchronization sequence; and iteratively averaging the reference sampling time points to obtain an estimated reference sampling time point.
Claim 12
Dependent Claim
53 words
The method of claim 9 wherein said step of iteratively averaging further includes the step of: applying a weighting function to the latest selected reference sampling time point corresponding to the latest incoming synchronization sequence, said weighting function assuming a zero value when the selected comparison value is beneath a predetermined threshold value.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-07-12 | 1997-01-11 | 1997-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-07-12 | 2001-01-11 | 2001-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-07-12 | 2005-01-11 | 2005-07-13 | $7700.00 | Window Closed / Lapsed |