US6134286A — Synchronization techniques and systems for radioc…

Claim 1

Independent Claim 96 words

A receiver comprising: a frequency estimator for determining a first estimate of frequency offset associated with a received signal; means for correcting said received signal using said first estimate to generate a corrected signal; a frequency and timing estimator which receives said corrected signal and determines a second estimate of frequency offset using a unique word known to said receiver and for outputting a timing estimate; means for further correcting said corrected signal using said second estimate to generate a frequency corrected signal; and means for synchronizing to said frequency corrected signal using said timing estimate.

Claim 2

Dependent Claim 96 words

A receiver comprising: a frequency estimator for determining a first estimate of frequency offset associated with a received signal; means for correcting said received signal using said first estimate to generate a corrected signal; a frequency and timing estimator which receives said corrected signal and determines a second estimate of frequency offset using a unique word known to said receiver and for outputting a timing estimate; means for further correcting said corrected signal using said second estimate to generate a frequency corrected signal; and means for synchronizing to said frequency corrected signal using said timing estimate.

Claim 3

Dependent Claim 58 words

The receiver of claim 1, wherein said first frequency estimator further comprises: a device for providing differential phase information between samples of said received signal; an averaging unit for averaging said differential phase information to generate an average value; and a scaling unit for scaling said average value to adjust for bias and to generate said first estimate.

Claim 4

Dependent Claim 27 words

The receiver of claim 1, wherein said means for correcting further comprises: a multiplier for multiplying a value related to said first estimate with said received signal.

Claim 5

Dependent Claim 73 words

The receiver of claim 1, wherein said frequency and timing estimator further comprises: a first differential demodulator for differentially demodulating said corrected signal; a second differential demodulator for differentially demodulating said unique word; and a correlator for providing a first set of correlation values between said differentially demodulated corrected signal and said differentially demodulated unique word, wherein a correlation peak associated with said correlation values provides an initial value of said timing estimate.

Claim 6

Dependent Claim 91 words

The receiver of claim 4, wherein said fine frequency and timing estimator further comprises: means for selecting said correlation peak and a predetermined number of samples surrounding said correlation peak; a two-dimensional coherent correlator which uses said selected number of samples and said correlation peak to correlating said unique word with a plurality of frequency offset and time-shifted versions of said received signal to generate a second set of correlation values; and an interpolator for smoothing a selected subset of said second set of correlation values to generate said second estimate.

Claim 7

Dependent Claim 28 words

The receiver of claim 1, wherein said means for further correcting further comprises: a multiplier for multiplying a value related to said second estimate with said received signal.

Claim 8

Dependent Claim 36 words

The receiver of claim 1, wherein said means for synchronizing further comprises: a correlator for correlating said unique word with said frequency corrected signal to identify a location of said unique word within said received signal.

Claim 9

Dependent Claim 12 words

The receiver of claim 2, wherein said device is a differential demodulator.

Claim 10

Dependent Claim 14 words

The receiver of claim 2, wherein said device includes at least one coherent correlator.

Claim 11

Dependent Claim 24 words

The receiver of claim 1, wherein said received signal is received using at least one of the following access methodologies: FDMA, TDMA and CDMA.

Claim 12

Dependent Claim 88 words

A receiver for receiving a signal including a frame of information, said frame including a unique word, said receiver comprising: a coarse estimator for coarsely estimating a frequency offset of said signal and correcting said signal using said estimated offset; a fine estimator for receiving said corrected signal, estimating a fine frequency offset using said unique word, correcting said corrected signal using said estimated fine frequency offset and identifying a location of said unique word within said frame; and a demodulator for demodulating said signal using said location.

Claim 13

Dependent Claim 88 words

A receiver for receiving a signal including a frame of information, said frame including a unique word, said receiver comprising: a coarse estimator for coarsely estimating a frequency offset of said signal and correcting said signal using said estimated offset; a fine estimator for receiving said corrected signal, estimating a fine frequency offset using said unique word, correcting said corrected signal using said estimated fine frequency offset and identifying a location of said unique word within said frame; and a demodulator for demodulating said signal using said location.

Claim 14

Independent Claim 73 words

A device for estimating a frequency offset associated with a received signal comprising: a first unit for providing differential phase information between samples of said received signal; an averaging unit for averaging said differential phase information to generate an average value; a scaling unit for scaling said average value to adjust for bias and to generate said frequency offset estimate; and a second unit for forming the conjugate of said frequency offset estimate.

Claim 15

Independent Claim 73 words

A device for estimating a frequency offset associated with a received signal comprising: a first unit for providing differential phase information between samples of said received signal; an averaging unit for averaging said differential phase information to generate an average value; a scaling unit for scaling said average value to adjust for bias and to generate said frequency offset estimate; and a second unit for forming the conjugate of said frequency offset estimate.

Claim 16

Dependent Claim 13 words

The device of claim 12, wherein said first unit is a differential demodulator.

Claim 17

Dependent Claim 15 words

The device of claim 12, wherein said first unit includes at least one coherent correlator.

Claim 18

Independent Claim 112 words

A device for estimating a frequency offset associated with a received signal and for estimating a location of a unique word within said received signal comprising: a first differential demodulator for differentially demodulating samples associated with said received signal; a second differential demodulator for differentially demodulating said unique word; a correlator for providing a first set of correlation values between said differentially demodulated received signal and said differentially demodulated unique word, wherein a correlation peak associated with said correlation values provides initial values of said frequency offset estimate and said timing estimate; and means for determining if said initial values of said frequency offset estimate and said timing estimate can be improved.

Claim 19

Independent Claim 112 words

A device for estimating a frequency offset associated with a received signal and for estimating a location of a unique word within said received signal comprising: a first differential demodulator for differentially demodulating samples associated with said received signal; a second differential demodulator for differentially demodulating said unique word; a correlator for providing a first set of correlation values between said differentially demodulated received signal and said differentially demodulated unique word, wherein a correlation peak associated with said correlation values provides initial values of said frequency offset estimate and said timing estimate; and means for determining if said initial values of said frequency offset estimate and said timing estimate can be improved.

Claim 20

Dependent Claim 93 words

The device of claim 15 wherein said means for determining further comprises: means for selecting said correlation peak and a predetermined number of samples surrounding said correlation peak; a two-dimensional coherent correlator which uses said selected number of samples and said correlation peak to correlating said unique word with a plurality of frequency offset and time-shifted versions of said received signal to generate a second set of correlation values; and an interpolator for smoothing a selected subset of said second set of correlation values to generate said frequency offset estimate and timing estimate.

Claim 21

Dependent Claim 59 words

The device of claim 16, wherein said interpolator is a quadratic interpolator that operates according to the following equation: ##EQU2## wherein y 0 , y 1 and y 2 are said selected subset of correlation values; and x 0 , x 1 and x 2 are frequencies corresponding to y 0 , y 1 and y 2 , respectively.

Claim 22

Independent Claim 81 words

A method of synchronizing to a data stream transmitted in frame format and having a unique word, comprising the steps of: adjusting the data stream to provide a frequency corrected data stream; correlating said frequency corrected data stream with a copy of said unique word to provide a plurality of correlation values; calculating a frequency estimate using at least one of said plurality of correlation values; correcting said data stream using said frequency estimate; and synchronizing to said corrected data stream.

Claim 23

Independent Claim 81 words

A method of synchronizing to a data stream transmitted in frame format and having a unique word, comprising the steps of: adjusting the data stream to provide a frequency corrected data stream; correlating said frequency corrected data stream with a copy of said unique word to provide a plurality of correlation values; calculating a frequency estimate using at least one of said plurality of correlation values; correcting said data stream using said frequency estimate; and synchronizing to said corrected data stream.

Claim 24

Dependent Claim 58 words

A method according to claim 18, wherein said step of adjusting the data stream to provide a frequency corrected data stream further comprises the steps of: differentially demodulating samples of said data stream; and averaging and scaling said differential samples to generate a coarse frequency offset estimate; and rotating said data stream by said coarse frequency offset estimate.

Claim 25

Dependent Claim 32 words

A method according to claim 18, wherein said step of correlating further comprises the steps of: differentially demodulating said frequency corrected data stream and said unique word prior to performing said correlation.

Claim 26

Dependent Claim 72 words

A method according to claim 18, wherein said step of calculating further comprises: performing a 2-D search over a number of frequency bins and a number of sample points selected based upon said at least one of said plurality of correlation values to identify a set of correlation values, and performing a quadratic interpolation of said set of correlation values and a set of corresponding frequency estimates to identify said frequency estimate.

Claim 27

Dependent Claim 48 words

The receiver of claim 11, further comprising: a first filter upstream of said course estimator for filtering said signal; and a second filter for filtering said corrected signal prior to said corrected signal being input to said fine estimator, said second filter being narrower than said first filter.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2003-10-17	2004-04-17	2004-10-17	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2007-10-17	2008-04-17	2008-10-17	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2011-10-17	2012-04-17	2012-10-17	$7700.00	Window Closed / Lapsed

Synchronization techniques and systems for radiocommunication

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