US5606580A
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Method of adjusting the length of a data block in a time-division multiple access communication system
Assignee: Alcatel Lucent NV
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Filing: 1994-07-19
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Granted: 1997-02-25
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Expires: 2014-07-19
Abstract
Abstract A method for adjusting the length of a data block in a time-division multiple access communication system includes estimating the impulse response of a communication channel from received symbols of a reference sequence, estimating a signal-to-noise ratio from the channel impulse response, and estimating a maximum Doppler shift. Using these estimations, upper and lower limit functions of a normalized estimated mean squared error are calculated, and the length of the data block is adjusted to an optimal length determined from the upper and lower limit functions.
Inventors
- 👤 Christophe Mourot
- 👤 Vinod Kumar
- 👤 Jean-Claude Dany
- 👤 Armelle Wautier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:32
CPC Classifications
H; H04; H04L; H04L1/00; H04L1/0001; H04L1/0006; H04L1/0007; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L2025/03777; H04L2025/03783; H04L2025/03796
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
265 words
A method of adjusting the length of a data block (BD) in accordance with time-varying behavior of a communication channel, the data block being transmitted as a signal on the time-varying communication channel of a time-division multiple access (TDMA) communication system, the signal being received at a receiver, said data block (BD) comprising: a training sequence (SA) including a reference sequence (SR) of length P; and a data sequence (D) of length n s containing data symbols having a symbol interval (T s ), said communication channel having an impulse response of finite length K, the method comprising the steps of: estimating the impulse response of the communication channel from received symbols of the reference sequence (SR); estimating a signal-to-noise ratio from the channel impulse response; estimating a maximum doppler shift of the signal at the receiver; calculating, from the signal-to-noise ratio, the doppler shift, the length K of the impulse response, the length P of the reference sequence (SR) and the symbol interval (T s ), lower and upper limit functions of normalized estimate mean squared error (E min (n s ), E max (n s )) as a function of the length n s of the data sequence (D); determining a range for an optimal length of the data sequence (D) from the upper and lower limit functions and from a predetermined range of mean squared error which is acceptable in the communication system; and adjusting the length n s of the data sequence (D) to a length n opt which lies within said range for an optimal length of the data sequence.
Claim 2
Independent Claim
265 words
A method of adjusting the length of a data block (BD) in accordance with time-varying behavior of a communication channel, the data block being transmitted as a signal on the time-varying communication channel of a time-division multiple access (TDMA) communication system, the signal being received at a receiver, said data block (BD) comprising: a training sequence (SA) including a reference sequence (SR) of length P; and a data sequence (D) of length n s containing data symbols having a symbol interval (T s ), said communication channel having an impulse response of finite length K, the method comprising the steps of: estimating the impulse response of the communication channel from received symbols of the reference sequence (SR); estimating a signal-to-noise ratio from the channel impulse response; estimating a maximum doppler shift of the signal at the receiver; calculating, from the signal-to-noise ratio, the doppler shift, the length K of the impulse response, the length P of the reference sequence (SR) and the symbol interval (T s ), lower and upper limit functions of normalized estimate mean squared error (E min (n s ), E max (n s )) as a function of the length n s of the data sequence (D); determining a range for an optimal length of the data sequence (D) from the upper and lower limit functions and from a predetermined range of mean squared error which is acceptable in the communication system; and adjusting the length n s of the data sequence (D) to a length n opt which lies within said range for an optimal length of the data sequence.
Claim 3
Dependent Claim
101 words
The method according to claim 1, further comprising the steps of: calculating, from the lower and upper limit functions, reference sequence lower and upper limit functions (E m (P), E M (P)) bracketing a normalized estimate mean squared error corresponding to the reference sequence; and determining a range for an optimal length of the reference sequence (SR) from said reference sequence lower and upper limit functions (E m (P), E M (P)); and adjusting the length P of the reference sequence (SR) to a length P opt which lies within said range for an optimal length of the reference sequence (SR).
Claim 4
Dependent Claim
76 words
Method according to claim 2, the normalized estimate mean squared error is limited by lower and upper limit functions (E m (P), E M (P)) as follows: ##EQU38## where: K is the length of the channel, P is the length of the reference sequence (SR), T s is the symbol interval, No/2 is a bilateral density of Gaussian additive white noise, E b is the energy transmitted per bit, f d is the maximal Doppler shift.
Claim 5
Dependent Claim
68 words
Method according to claim 3, wherein the optimal length of the reference sequence is bracketed by lower and upper limits (P M , P m ) as follows: ##EQU39## where: K is the length of the channel, T s is the symbol interval, No/2 is a bilateral density of Gaussian additive white noise, E b is the energy transmitted per bit, f d is the maximal Doppler shift.
Claim 6
Dependent Claim
160 words
The method according to claim 1, wherein: the data block comprises constant amplitude zero autocorrelation (CAZAC) or pseudo-CAZAC type sequences; noise affecting the communication channel is approximated by the Gaussian additive white noise; the data sequence (D) is transmitted after the reference sequence (SR); the lower and upper limit functions (E min (n s ), E max (n s )) are calculated as follows: ##EQU40## where n s is the length of the data sequence, K is the length of the channel, P is the length of the reference sequence (SR), T s is the symbol interval, No/2 is a bilateral density of Gaussian additive white noise, E b is the energy transmitted per bit, f d is the maximal Doppler shift; and the range for the optimal length (n opt ) is determined by applying the range of predetermined mean squared error to the lower and upper limit functions (E min (n s ), E max (n s ).
Claim 7
Dependent Claim
155 words
Method according to claim 1 wherein: the data block comprises constant amplitude zero autocorrelation (CAZAC) and pseudo-CAZAC type sequences; noise affecting the communication channel is approximated by Gaussian additive white noise; the data sequence (D) is transmitted before the reference sequence (SR); the lower and upper limit functions (E min (n s ), E max (n s )) are calculated as follows: ##EQU41## where n s is the length of the data sequence, K is the length of the channel, P is the length of the reference sequence (SR), T s is the symbol interval, No/2 is a bilateral density of Gaussian additive white noise, E b is the energy transmitted per bit, f d is the maximal Doppler shift; and the range for the optimal length is determined by applying the range of predetermined mean squared error to the lower and upper limit functions (E min (n s ), E max (n s )).
Claim 8
Dependent Claim
34 words
The method according to claim 1, wherein the data sequence comprises a preceding data sequence which is transmitted before the reference sequence, and a following data sequence which is transmitted after the reference sequence.
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) | 2000-02-25 | 2000-08-26 | 2001-02-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-02-25 | 2004-08-26 | 2005-02-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-02-25 | 2008-08-26 | 2009-02-25 | $7700.00 | Window Closed / Lapsed |