US5506869A
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US
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Methods and apparatus for estimating carrier-to-interference ratios at cellular radio base stations
Assignee: Benhov GmbH LLC
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Filing: 1994-10-27
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Granted: 1996-04-09
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Expires: 2014-10-27
Abstract
Abstract In methods and apparatus for estimating carrier-to-interference ratios of signals transmitted between cellular radio base stations and mobile units, a SAT signal is transmitted from a base station to a mobile unit served by that base station. The mobile unit receives the SAT signal and retransmits the received SAT signal to the base station. A first order autoregressive parameter is calculated for the received SAT signal at the base station is correlated with a tabulated carrier-to-interference ratio estimate to estimate the carrier-to-interference ratio of the signals.
Inventors
- 👤 Claude Royer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 08:38
CPC Classifications
H; H04; H04W; H04W24/00; H04W84/00; H04W84/02; H04W84/04; H04W84/042
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
102 words
A method for estimating carrier-to-interference ratios of signals transmitted between cellular radio base stations and mobile units, the method comprising: transmitting a Supervisory Audio Tone (SAT) signal from a base station to a mobile unit served by that base station; receiving the SAT signal at the mobile unit; retransmitting the received SAT signal at the mobile unit; receiving the retransmitted SAT signal at the base station; calculating a first order autoregressive parameter for the received SAT signal at the base station; and correlating the first order autoregressive parameter with a tabulated carrier-to-interference ratio estimate to estimate the carrier-to-interference ratio of the signals.
Claim 2
Independent Claim
102 words
A method for estimating carrier-to-interference ratios of signals transmitted between cellular radio base stations and mobile units, the method comprising: transmitting a Supervisory Audio Tone (SAT) signal from a base station to a mobile unit served by that base station; receiving the SAT signal at the mobile unit; retransmitting the received SAT signal at the mobile unit; receiving the retransmitted SAT signal at the base station; calculating a first order autoregressive parameter for the received SAT signal at the base station; and correlating the first order autoregressive parameter with a tabulated carrier-to-interference ratio estimate to estimate the carrier-to-interference ratio of the signals.
Claim 3
Dependent Claim
75 words
A method as defined in claim 1, wherein the step of calculating the first order autoregressive parameter comprises: Frequency Modulation (FM) demodulating a composite received signal; frequency shifting the demodulated signal to center a SAT frequency band of the demodulated signal at a frequency origin; bandpass filtering the frequency shifted signal to attenuate signal components outside of the SAT frequency band; and decimating the filtered signal to reduce a sample rate of the filtered signal.
Claim 4
Dependent Claim
45 words
A method as defined in claim 2, wherein: the SAT signal has a nominal frequency selected from 5970 Hz, 6000 Hz and 6030 Hz; and the step of decimating the filtered signal reduces the sample rate of the filtered signal to 120 samples per second.
Claim 5
Dependent Claim
68 words
A method as defined in claim 2, wherein the step of calculating the first order autoregressive parameter further comprises, calculating a sequence a(n) of first order autoregressive parameters according to: a(n)=a(n-1)-2k e(n)z*(n-1) where e(n) is a sequence of complex-valued filter residuals given by: e(n)=z(n)+a(n-1)z(n-1) z(n-1) is a sequence of complex-valued samples comprising the decimated signal, z*(n-1) is a complex conjugate of z(n-1), and k is a real-valued constant.
Claim 6
Dependent Claim
30 words
A method as defined in claim 4, further comprising initializing a(1) at a value selected from -j, 1 and j according to a SAT frequency assigned to the base station.
Claim 7
Dependent Claim
51 words
A method as defined in claim 1, wherein the step of correlating the first order autoregressive parameter with a tabulated carrier-to-interference ratio estimate comprises: calculating a squared magnitude of the first order autoregressive parameter; and correlating the squared magnitude of the first order autoregressive parameter with a tabulated carrier-to-interference ratio estimate.
Claim 8
Dependent Claim
56 words
A method as defined in claim 6, wherein the step of correlating the squared magnitude of the first order autoregressive parameter with a tabulated carrier-to-interference ratio estimate comprises: averaging the squared magnitude of the first order autoregressive parameter over time to calculate a carrier-to-interference index; and correlating the carrier-to-interference index with a tabulated carrier-to-interference ratio estimate.
Claim 9
Dependent Claim
70 words
A method as defined in claim 7, wherein: the step of averaging the squared magnitude of the first order autoregressive parameter comprises calculating both short term and long term averages to generate short term and long term carrier-to-interference indices respectively; and the step of correlating the carrier-to-interference index with a tabulated carrier-to-interference ratio estimate comprises correlating both short term and long term carrier-to-interference indices with respective tabulated carrier-to-interference ratio estimates.
Claim 10
Dependent Claim
65 words
Apparatus for estimating carrier-to-interference ratios of signals transmitted between cellular radio base stations and mobile units, the apparatus comprising: a signal processor for calculating a first order autoregressive parameter for a received Supervisory Audio Tone (SAT) signal at the base station; and a database for correlating the first order autoregressive parameter with a tabulated carrier-to-interference ratio estimate to estimate the carrier-to-interference ratio of the signals.
Claim 11
Dependent Claim
65 words
Apparatus for estimating carrier-to-interference ratios of signals transmitted between cellular radio base stations and mobile units, the apparatus comprising: a signal processor for calculating a first order autoregressive parameter for a received Supervisory Audio Tone (SAT) signal at the base station; and a database for correlating the first order autoregressive parameter with a tabulated carrier-to-interference ratio estimate to estimate the carrier-to-interference ratio of the signals.
Claim 12
Dependent Claim
66 words
Apparatus as defined in claim 9, wherein the signal processor is operable to: Frequency Modulation (FM) demodulate a composite received signal; frequency shift the demodulated signal to center a SAT frequency band of the demodulated signal at a frequency origin; bandpass filter the frequency shifted signal to attenuate signal components outside of the SAT frequency band; and decimate the filtered signal to reduce the sample rate.
Claim 13
Dependent Claim
48 words
Apparatus as defined in claim 10, wherein: the SAT signal has a nominal frequency selected from 5970 Hz, 6000 Hz and 6030 Hz; and the signal processor is operable to decimate the filtered signal to reduce a sample rate of the filtered signal to 120 samples per second.
Claim 14
Dependent Claim
62 words
Apparatus as defined in claim 10, wherein the signal processor is operable to calculate a sequence a(n) of first order autoregressive parameters according to: a(n)=a(n-1)-2k e(n)z*(n-1) where e(n) is a sequence of complex-valued filter residuals given by: e(n)=z(n)+a(n-1)z(n-1) z(n-1) is a sequence of complex-valued samples comprising the decimated signal, z*(n-1) is a complex conjugate of z(n-1), and k is a real-valued constant.
Claim 15
Dependent Claim
34 words
Apparatus as defined in claim 12, wherein the signal processor is operable to initialize a(1) at a value selected from -j, 1 and j according to a SAT frequency assigned to the base station.
Claim 16
Dependent Claim
44 words
Apparatus as defined in claim 9, wherein the signal processor is operable to: calculate a squared magnitude of the first order autoregressive parameter; and correlate the squared magnitude of the first order autoregressive parameter with a carrier-to-interference ratio estimate tabulated in the carrier-to-interference database.
Claim 17
Dependent Claim
41 words
Apparatus as defined in claim 14, wherein the signal processor is operable to: average the squared magnitude of the first order autoregressive parameter over time to calculate a carrier-to-interference index; and correlate the carrier-to-interference index with a tabulated carrier-to-interference ratio estimate.
Claim 18
Dependent Claim
47 words
Apparatus as defined in claim 15, wherein the signal processor is operable to: calculate both short term and long term averages to generate short term and long term carrier-to-interference indices respectively; and correlate both short term and long term carrier-to-interference indices with respective tabulated carrier-to-interference ratio estimates.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-04-09 | 1999-10-09 | 2000-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-04-09 | 2003-10-09 | 2004-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-04-09 | 2007-10-09 | 2008-04-09 | $7700.00 | Window Closed / Lapsed |