EP0550143A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
MLSE for mobile radio channels
Assignee: AT&T Inc
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Filing: 1992-11-23
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Granted: —
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Expires: 2012-11-23
Abstract
Abstract An equalizer/decoder (Fig. 12) for a communication channel presenting impairments to error-free reception of transmitted symbols includes a modified Viterbi decoder (930) operating on samples of received signals in a plurality of equivalent subchannels (on 910). Estimates of each of the subchannels are updated using a locally best estimate (960) in the Viterbi trellis processing, thereby avoiding delay in updating channel estimates in a rapidly changing channel such as a digital cellular communications channels. A leaky predictor channel updating technique also proves advantageous in an alternative embodiment. <IMAGE>
Inventors
- 👤 Stephen Russell Huszar
- 👤 Nambirajan Seshadri
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 12:37
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/38; H04L25/40; H04L25/49; H04L1/00; H04L1/004; H04L1/0045; H04L1/0054; H03; H03M; H03M13/00; H03M13/25; H03M13/37; H03M13/39; H03M13/41; H04L1/0047; H04L25/02; H04L25/0202; H04L25/0212; H04L25/024; H04L25/025; H04L25/03; H04L25/03006; H04L25/03178; H04L25/03248; H04L25/03254; H04L25/03267; H04L25/03292; H04L25/03312; H04L25/03324
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
163 words
A method for decoding time varying signals comprising receiving time varying signals, r(t), from a communications channel, which signals represent sequences of symbols, c k , k=1,2,3,..., supplied to said communications channel at a symbol rate of 1/T, for the kth period of duration T, with R an integer, sampling r(t) at rate R/T to produce a set of R samples of r(t), r k (ℓ), ℓ = 1,2,...,R, for each of a set of candidate (M+1)-symbol sequences, c k-m , c k-(m-1) ,..., c k-1 , c k , generating a set of R values, s k (ℓ), ℓ = 1,2,...,R, each representing a partial estimates of an output of said channel, forming an error signal reflecting the difference between each of r k (ℓ) and s k (ℓ), ℓ = 1,2,...,R, for each of said candidate sequences, and selecting as a symbol supplied to said channel a symbol in the candidate sequence which yields the minimum value for said error signal.
Claim 2
Dependent Claim
15 words
The method of claim 1 wherein r(t) is received from a time-varying multi-path communications channel.
Claim 3
Dependent Claim
27 words
The method of claim 1 wherein said selecting comprises selecting the symbol c k from said candidate sequence which yields said minimum value for said error signal.
Claim 4
Dependent Claim
38 words
The method of claim 1 wherein said forming an error signal comprises forming, for each value of ℓ, the square of the difference between each of said r k (ℓ) and s k (ℓ) and summing said differences.
Claim 5
Dependent Claim
27 words
The method of claim 1 wherein said s k (ℓ) is based on a convolution of said c k sequence with samples of channel impulse response estimates.
Claim 6
Dependent Claim
11 words
The method of claim 5, wherein said convolutions are given by
Claim 7
Dependent Claim
40 words
The method of claim 1, wherein said step of generating a set of R values, s k (ℓ) comprises determining each of said partial estimates of said outputs based on a respective partial estimate of the characteristics of said channel.
Claim 8
Dependent Claim
26 words
The method of claim 7 comprising the further step of updating said partial estimates of the characteristics of said channel in response to said error signal.
Claim 9
Dependent Claim
43 words
The method of claim 7 comprising the further step of updating said partial estimates of the characteristics of said channel in response to a signal representing the difference between each of said r k (ℓ) and a noiseless estimate of the channel output.
Claim 10
Dependent Claim
27 words
The method of claim 9, wherein said noiseless estimate of the channel output is generated in response to a tentative decision as to the symbol actually sent.
Claim 11
Dependent Claim
44 words
The method of claim 7 comprising the further step of updating each of said partial estimates of the characteristics of said channel in response to a signal representing a prediction based on the current estimates of respective ones of said characteristics of said channel.
References Cited (Backward Citations)
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