Patent US5574989A successfully refreshed from Google Patents.
US5574989A
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Time division multiple access cellular communication system and method employing base station diversity transmission
Assignee: The AT&T MVPD Group LLC
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Filing: 1994-10-13
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Granted: 1996-11-12
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Expires: 2014-10-13
Abstract
Abstract A cellular base station (10) in a digital cellular system employs transmitting circuitry in which voice signals (15) are processed at a low frequency level (12) into two separate paths. A first of the low frequency signals is variably delayed (20), and the first and the other low frequency signals are upconverted to radio frequency level (16,22) for transmission over independent time-spaced transmission paths (26,28) to cellular receivers. A receiver downconverts and demodulates the radio frequency diversity signals, and then combines the demodulated diversity signals to generate an equalized combination diversity signal for receiver output processing.
Inventors
- 👤 John Watson
- 👤 Youngky Kim
- 👤 Long Huynh
- 👤 Michael Parr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:49
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/02; H04B7/04; H04B7/06; H04B7/0613; H04B7/0667; H04B7/0671
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
150 words
A communication system comprising: a base station having: means for generating a first low frequency signal corresponding to an information signal; means for processing the first low frequency signal to form a first radio frequency signal corresponding thereto and a second radio frequency signal corresponding thereto; means for time delaying the second radio frequency signal relative to the first radio frequency signal; means for transmitting the first and second radio frequency signals over independent transmission paths; and at least one receiver having: means for receiving and summing the transmitted first and second radio frequency signals; means for separating and downconverting the summed first and second radio frequency signals to generate downconverted time diversity signals; means for demodulating the separated downconverted diversity signals to generate separate demodulated time diversity signals; and equalizing means for combining the separate demodulated time diversity signals to generate an equalized combination signal for receiver output processing.
Claim 2
Dependent Claim
150 words
A communication system comprising: a base station having: means for generating a first low frequency signal corresponding to an information signal; means for processing the first low frequency signal to form a first radio frequency signal corresponding thereto and a second radio frequency signal corresponding thereto; means for time delaying the second radio frequency signal relative to the first radio frequency signal; means for transmitting the first and second radio frequency signals over independent transmission paths; and at least one receiver having: means for receiving and summing the transmitted first and second radio frequency signals; means for separating and downconverting the summed first and second radio frequency signals to generate downconverted time diversity signals; means for demodulating the separated downconverted diversity signals to generate separate demodulated time diversity signals; and equalizing means for combining the separate demodulated time diversity signals to generate an equalized combination signal for receiver output processing.
Claim 3
Dependent Claim
35 words
The communication system of claim 1 wherein: the transmitting means includes respective antennas for the respective first and second radio frequency signals spaced from each other on a single tower to create independent transmission paths.
Claim 4
Dependent Claim
25 words
The communication system of claim 1 wherein a digital signal processor is provided and includes at least the generating means and the time delaying means.
Claim 5
Dependent Claim
42 words
The communication system of claim 1, wherein said means for time delaying the second radio frequency signal relative to the first radio frequency signal includes means for varying the delay between the second radio frequency signal and the first radio frequency signal.
Claim 6
Dependent Claim
27 words
The communication system of claim 4 wherein a digital signal processor is provided and includes at least the generating means and the time delaying and varying means.
Claim 7
Dependent Claim
119 words
The communication system of claim 1, wherein said means for processing the first low frequency signal to form a first radio frequency signal corresponding thereto and a second radio frequency signal corresponding thereto includes means for forming a second low frequency signal from the first low frequency signal to form said second radio frequency signal corresponding to said second low frequency signal, and said means for time delaying the second radio frequency signal relative to the first radio frequency signal further comprises means for time delaying said second low frequency signal relative to said first low frequency signal, whereby the time delay in the second radio frequency signal corresponds to the time delay in the second low frequency signal.
Claim 8
Dependent Claim
42 words
The communication system of claim 6 wherein said means for time delaying said second low frequency signal relative to said first low frequency signal includes means for varying the delay between the second low frequency signal and the first low frequency signal.
Claim 9
Independent Claim
152 words
A method for operating a communication system having a base station and at least one receiver, the steps of the method comprising: generating a first low frequency signal corresponding to an input information signal; processing the first low frequency signal to form a first radio frequency signal corresponding thereto and a second radio frequency signal corresponding thereto; time delaying the second radio frequency signal relative to the first radio frequency signal; transmitting the first and second radio frequency signals from the base station over independent transmission paths; receiving and summing the first and second radio frequency signals in the at least one receiver; separating and downconverting the summed first and second radio frequency signals to generate downconverted time diversity signals; demodulating the separated downconverted diversity signals to generate separate demodulated diversity signals; and combining the separate demodulated diversity signals in an equalizer to generate an equalized combination signal for receiver output processing.
Claim 10
Independent Claim
152 words
A method for operating a communication system having a base station and at least one receiver, the steps of the method comprising: generating a first low frequency signal corresponding to an input information signal; processing the first low frequency signal to form a first radio frequency signal corresponding thereto and a second radio frequency signal corresponding thereto; time delaying the second radio frequency signal relative to the first radio frequency signal; transmitting the first and second radio frequency signals from the base station over independent transmission paths; receiving and summing the first and second radio frequency signals in the at least one receiver; separating and downconverting the summed first and second radio frequency signals to generate downconverted time diversity signals; demodulating the separated downconverted diversity signals to generate separate demodulated diversity signals; and combining the separate demodulated diversity signals in an equalizer to generate an equalized combination signal for receiver output processing.
Claim 11
Dependent Claim
37 words
The method of claim 8 wherein: the signal transmitting step is performed with respective antennas for the respective first and second radio frequency signals spaced from each other on a single tower to create independent transmission paths.
Claim 12
Dependent Claim
29 words
The method of claim 8, wherein the time delaying step includes the step of varying the delay between the second radio frequency signal and the first radio frequency signal.
Claim 13
Dependent Claim
25 words
The method of claim 10 wherein the generating step, the time delaying step and the delay varying step are performed in a digital signal processor.
Claim 14
Dependent Claim
84 words
The method of claim 8, wherein the processing step includes the step of forming a second low frequency signal from the first low frequency signal to form said second radio frequency signal corresponding to said second low frequency signal, and wherein the time delaying step includes the step of time delaying said second low frequency signal relative to said first low frequency signal, whereby the time delay in the second radio frequency signal corresponds to the time delay in the second low frequency signal.
Claim 15
Dependent Claim
152 words
A communication system comprising: a base station having: means for generating a first low frequency signal corresponding to an input information signal; means for processing the first low frequency signal to form a first radio frequency signal corresponding thereto and a second radio frequency signal corresponding thereto; means for time delaying the second radio frequency signal relative to the first radio frequency signal; means for transmitting the first and second radio frequency signals over independent transmission paths; and at least one receiver having: means for receiving and summing the transmitted first and second radio frequency signals; means for separating and downconverting the summed first and second radio frequency signals to generate downconverted diversity signals; means for demodulating the downconverted diversity signals to generate demodulated diversity signals; and equalizing means including a maximum likelihood sequential estimator for combining the demodulated diversity signals to generate an equalized, high-quality combination signal for receiver output processing.
Claim 16
Dependent Claim
152 words
A communication system comprising: a base station having: means for generating a first low frequency signal corresponding to an input information signal; means for processing the first low frequency signal to form a first radio frequency signal corresponding thereto and a second radio frequency signal corresponding thereto; means for time delaying the second radio frequency signal relative to the first radio frequency signal; means for transmitting the first and second radio frequency signals over independent transmission paths; and at least one receiver having: means for receiving and summing the transmitted first and second radio frequency signals; means for separating and downconverting the summed first and second radio frequency signals to generate downconverted diversity signals; means for demodulating the downconverted diversity signals to generate demodulated diversity signals; and equalizing means including a maximum likelihood sequential estimator for combining the demodulated diversity signals to generate an equalized, high-quality combination signal for receiver output processing.
Claim 17
Dependent Claim
42 words
The communication system of claim 13, wherein said means for time delaying the second radio frequency signal relative to the first radio frequency signal includes means for varying the delay between the second radio frequency signal and the first radio frequency signal.
Claim 18
Dependent Claim
27 words
The communication system of claim 14, wherein a digital signal processor is provided and includes at least the generating means and the time delaying and varying means.
Claim 19
Dependent Claim
119 words
The communication system of claim 13, wherein said means for processing the first low frequency signal to form a first radio frequency signal corresponding thereto and a second radio frequency signal corresponding thereto includes means for forming a second low frequency signal from the first low frequency signal to form said second radio frequency signal corresponding to said second low frequency signal, and said means for time delaying the second radio frequency signal relative to the first radio frequency signal further comprises means for time delaying said second low frequency signal relative to said first low frequency signal, whereby the time delay in the second radio frequency signal corresponds to the time delay in the second low frequency signal.
Claim 20
Dependent Claim
42 words
The communication system of claim 16, wherein said means for time delaying said second low frequency signal relative to said first low frequency signal includes means for varying the delay between the second low frequency signal and the first low frequency signal.
Claim 21
Independent Claim
156 words
A method for operating a communication system having a base station and at least one receiver, the steps of the method comprising: generating a first low frequency signal corresponding to an input information signal; processing the first low frequency signal to form a first radio frequency signal corresponding thereto and a second radio frequency signal corresponding thereto; time delaying the second radio frequency signal relative to the first radio frequency signal; transmitting the first and second radio frequency signals from the base station over independent transmission paths; receiving and summing the first and second radio frequency signals in the at least one receiver; separating and downconverting the summed first and second radio frequency signals to generate downconverted diversity signals; demodulating the downconverted diversity signals to generate demodulated diversity signals; and combining the demodulated diversity signals in an equalizer which uses a maximum likelihood sequential estimator to generate an equalized, high-quality combination signal for receiver output processing.
Claim 22
Independent Claim
156 words
A method for operating a communication system having a base station and at least one receiver, the steps of the method comprising: generating a first low frequency signal corresponding to an input information signal; processing the first low frequency signal to form a first radio frequency signal corresponding thereto and a second radio frequency signal corresponding thereto; time delaying the second radio frequency signal relative to the first radio frequency signal; transmitting the first and second radio frequency signals from the base station over independent transmission paths; receiving and summing the first and second radio frequency signals in the at least one receiver; separating and downconverting the summed first and second radio frequency signals to generate downconverted diversity signals; demodulating the downconverted diversity signals to generate demodulated diversity signals; and combining the demodulated diversity signals in an equalizer which uses a maximum likelihood sequential estimator to generate an equalized, high-quality combination signal for receiver output processing.
Claim 23
Dependent Claim
29 words
The method of claim 18, wherein the time delaying step includes the step of varying the delay between the second radio frequency signal and the first radio frequency signal.
Claim 24
Dependent Claim
84 words
The method of claim 18, wherein the processing step includes the step of forming a second low frequency signal from the first low frequency signal to form said second radio frequency signal corresponding to said second low frequency signal, and wherein the time delaying step includes the step of time delaying said second low frequency signal relative to said first low frequency signal, whereby the time delay in the second radio frequency signal corresponds to the time delay in the second low frequency signal.
Claim 25
Dependent Claim
29 words
The method of claim 20, wherein the time delaying step includes the step of varying the delay between the second low frequency signal and the first low frequency signal.
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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) | 1999-11-12 | 2000-05-13 | 2000-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-11-12 | 2004-05-13 | 2004-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-11-12 | 2008-05-13 | 2008-11-12 | $7700.00 | Window Closed / Lapsed |