US5299235A
Expired / Lapsed
US
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Time synchronization of a receiver in a digital radio telephone system
Assignee: Telefonaktiebolaget LM Ericsson AB
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Filing: 1991-09-10
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Granted: 1994-03-29
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Expires: 2011-09-10
Abstract
Abstract A method for improving time synchronization of digital data signals in receivers by using more than one known data sequence to provide a plurality of timing recovery functions and based on these, one or more optimal sampling points. By using existing data sequences in each frame, the disclosed method provides improved time synchronization without increasing transmission overhead.
Inventors
- 👤 Gustav Larsson
- 👤 Karim Jamal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:26
CPC Classifications
H; H04; H04L; H04L7/00; H04L7/02; H04L7/033; H04L7/0334; H04L7/04
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
126 words
A method of time synchronizing and demodulating a received data signal comprising the steps of: providing at least two data sequences in said received data signal which are known to a receiver for each set of data fields to be demodulated, wherein said at least two data sequences include at least one synchronization sequence having good correlation properties and at least one sequence which does not have good correlation properties; calculating a timing recovery function for each of said at least two data sequences; finding, based on the calculated plurality of timing recovery functions, at least one sampling point; and demodulating each set of data fields of said received data signal using the resulting at least one sampling point as a reference for the demodulating position.
Claim 2
Independent Claim
126 words
A method of time synchronizing and demodulating a received data signal comprising the steps of: providing at least two data sequences in said received data signal which are known to a receiver for each set of data fields to be demodulated, wherein said at least two data sequences include at least one synchronization sequence having good correlation properties and at least one sequence which does not have good correlation properties; calculating a timing recovery function for each of said at least two data sequences; finding, based on the calculated plurality of timing recovery functions, at least one sampling point; and demodulating each set of data fields of said received data signal using the resulting at least one sampling point as a reference for the demodulating position.
Claim 3
Dependent Claim
50 words
The method of time synchronizing of claim 1 wherein said step of demodulating further comprises the steps of: determining a single sampling point using a combination of said plurality of timing recovery functions; and using said single sampling point as a reference point for demodulating the set of data fields.
Claim 4
Dependent Claim
15 words
The method of time synchronizing of claim 2 wherein said combination is a linear combination.
Claim 5
Dependent Claim
92 words
The method of time synchronizing of claim 1 wherein said step of demodulating further comprises the steps of: choosing one of said at least one sampling points which was calculated from a known data sequence closest to a current demodulation position within the set of data fields; using the chosen sampling point as a reference point for demodulating the set of data fields at the current demodulation position; incrementing the current demodulation position; and continuously repeating said choosing, using and incrementing steps for each demodulation position within the set of data fields.
Claim 6
Dependent Claim
66 words
The method of time synchronization of claim 1 wherein said step of demodulating further comprises the steps of: demodulating said set of data fields once for each of said at least one sampling points, each time using a different one of said sampling points as a reference for demodulating said set of data fields; and combining said plurality of demodulated signals based on a predetermined criterion.
Claim 7
Dependent Claim
19 words
The method of time synchronization of claim 5, wherein said predetermined criterion is a least sum of squared errors.
Claim 8
Dependent Claim
50 words
The method of time synchronizing of claim 1, wherein said step of providing further comprises the step of: wherein said at least one sequence which does not have good correlation properties is also used for a purpose other than synchronization, but remains constant during transmission of said received data signal.
Claim 9
Dependent Claim
35 words
The method of time synchronizing of claim 7 further comprising the step of: distinguishing a current traffic channel from a traffic co-channel using said at least one sequence which does not have good correlation properties.
Claim 10
Independent Claim
120 words
A method of time synchronizing and demodulating a received time slot within a frame in a communication signal between base and mobile stations in a mobile, cellular telephone system comprising the steps of: providing two or more data sequences which are known to a receiver in said time slot, wherein at least one of said data sequences is a synchronization sequence having good correlation properties and at least one of said data sequences is a control sequence which does not have good correlation properties; calculating a timing recovery function for each of two or more of said data sequences; and demodulating said time slot of said communication signal using one or more sampling points derived from said timing recovery functions.
Claim 11
Independent Claim
120 words
A method of time synchronizing and demodulating a received time slot within a frame in a communication signal between base and mobile stations in a mobile, cellular telephone system comprising the steps of: providing two or more data sequences which are known to a receiver in said time slot, wherein at least one of said data sequences is a synchronization sequence having good correlation properties and at least one of said data sequences is a control sequence which does not have good correlation properties; calculating a timing recovery function for each of two or more of said data sequences; and demodulating said time slot of said communication signal using one or more sampling points derived from said timing recovery functions.
Claim 12
Dependent Claim
49 words
The method of time synchronizing of claim 9 wherein said step of demodulating further comprises the steps of: determining a single sampling point using a combination of said plurality of timing recovery functions; and using said sampling point as a reference point for demodulating the set of data fields.
Claim 13
Dependent Claim
15 words
The method of time synchronizing of claim 10 wherein said combination is a linear combination.
Claim 14
Dependent Claim
81 words
The method of time synchronizing of claim 9 wherein said step of demodulating further comprises the steps of: choosing one of said one or more sampling points which was calculated from a known data sequence closest to a current demodulation position within the time slot; using the chosen sampling point as a reference point for demodulating the time slot; incrementing the current demodulation position; and continuously repeating said choosing, using and incrementing steps for each demodulation position within the time slot.
Claim 15
Dependent Claim
63 words
The method of time synchronization of claim 9 wherein said step of demodulating further comprises the steps of: demodulating said time slot once for each of said one or more sampling points, each time using a different one of said sampling points as a reference point for demodulating said time slot; and combining said plurality of demodulated signals based on a predetermined criterion.
Claim 16
Dependent Claim
19 words
The method of time synchronization of claim 13 wherein said predetermined criterion is a least sum of squared errors.
Claim 17
Dependent Claim
26 words
The method of time synchronization of claim 9 wherein said timing recovery function is derived from a correlation function for each of said known data sequences.
Claim 18
Dependent Claim
27 words
The method of time synchronization of claim 9 wherein said predetermined function is an error signal generated during equalizer training for each of said known data sequences.
Claim 19
Dependent Claim
31 words
The method of time synchronizing of claim 9, wherein said control sequence is also used for a purpose other than synchronization, but remains constant during transmission of said received data signal.
Claim 20
Dependent Claim
35 words
The method of time synchronizing of claim 17, further comprising the step of: distinguishing a current traffic channel from a traffic co-channel using said at lest one sequence which does not have good correlation properties.
Claim 21
Independent Claim
116 words
A system for time synchronizing and demodulating received data signal in a time division multiple access system wherein a time slot of said received data signal includes at least two known data sequences, wherein said at least two known data sequences include at least one synchronization sequence having good correlation properties and at least one sequence which does not have good correlation properties, said system comprising: means for calculating, for each of said at least two known data sequences, a predetermined function, and also for calculating at least one sampling points based on said predetermined functions; and means for demodulating said time slot of said received data signal using one or more of the sampling points.
Claim 22
Independent Claim
116 words
A system for time synchronizing and demodulating received data signal in a time division multiple access system wherein a time slot of said received data signal includes at least two known data sequences, wherein said at least two known data sequences include at least one synchronization sequence having good correlation properties and at least one sequence which does not have good correlation properties, said system comprising: means for calculating, for each of said at least two known data sequences, a predetermined function, and also for calculating at least one sampling points based on said predetermined functions; and means for demodulating said time slot of said received data signal using one or more of the sampling points.
Claim 23
Dependent Claim
43 words
The system for time synchronization of claim 19 wherein said means for demodulating further comprises: means for combining said timing recovery functions to determine a sampling point; and means for using said sampling point as a reference point for demodulating the time slot.
Claim 24
Dependent Claim
86 words
The system for time synchronization of claim 19 wherein said means for demodulating further comprises: means for choosing one of said at least one sampling points which was calculated from a known data sequence closest to a current demodulation position within the time slot; means for using the chosen sampling point as a reference point for demodulating the time slot; means for incrementing the current demodulation position; and means for continuously repeating said choosing, using and incrementing steps for each demodulation position within the time slot.
Claim 25
Dependent Claim
63 words
The system for time synchronization of claim 19 wherein said demodulating means further comprises: means for demodulating said time slot once for each of said at least one sampling points, each time using a different one of said sampling points as a reference point for demodulating said time slot; and means for combining said plurality of demodulated signals based on a predetermined criterion.
Claim 26
Dependent Claim
40 words
The system of time synchronization of claim 19, wherein said at least one sequence which does not have good correlation properties is also used for a purpose other than synchronization, but remains constant during transmission of said received data signal.
Claim 27
Dependent Claim
25 words
The system of time synchronization of claim 23 further comprising: means for distinguishing a current traffic channel from a traffic co-channel using said data field.
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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) | 1997-03-28 | 1997-09-27 | 1998-03-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-28 | 2001-09-27 | 2002-03-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-28 | 2005-09-27 | 2006-03-29 | $7700.00 | Window Closed / Lapsed |