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EP0604956A2
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EP
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Decision feedback equalizer with adaptive filter array operating as feedforward filter of the equalizer
Assignee: NEC Corp
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Filing: 1993-12-27
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Granted: —
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Expires: 2013-12-27
Abstract
Abstract In a decision feedback equalizer, symbols from an array of antennas (10 1 -10 N ) are fed to a first filter (12) where they are respectively multiplied with first weight coefficients and supplied to a combiner (15) where they are combined with second symbols to produce a combined symbol. A decision circuit (16) makes a decision on the combined symbol and produces a decision symbol. Decision symbols successively generated by the decision circuit are fed to a second filter (18) where they are respectively multiplied with second weight coefficients and supplied to the combiner (15) as the second symbols. A difference between the decision symbol and the combined symbol is detected to produce a decision error. Each of the first weight coefficients is updated according to the decision error and the symbol from each of the antenna systems and each of the second weight coefficients is updated according to the decision error and each of the decision symbols successively-supplied from the decision circuit so that the mean square value of the decision error is reduced to a minimum.
Inventors
- 👤 Ichiro C/O Nec Corporation Tsujimoto
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 00:20
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/02; H04B7/04; H04B7/08; H04B7/0837; H04B7/0842; H04B7/0848; H04B7/0854; H01; H01Q; H01Q3/00; H01Q3/26; H01Q3/2605; H04B1/00; H04B1/06; H04B1/10; H04B1/12; H04B1/123; H04B1/126
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
225 words
A decision feedback equalizer for an array of antenna systems each of which receives a modulated carrier and recovers a series of symbols from the carrier, the decision feedback equalizer comprising: first filter means connected to the antenna systems for respectively multiplying symbols from said antenna systems with first weight coefficients; combiner means for combining the multiplied symbols from said first filter means with second symbols applied thereto and producing therefrom a combined symbol; decision means for making a decision on the combined symbol and producing therefrom a decision symbol; second filter means for multiplying decision symbols successively supplied from said decision means respectively with second weight coefficients and applying the multiplied decision symbols as said second symbols to said combiner means; error detector means for detecting a difference between said decision symbol and said combined symbol and deriving therefrom a decision error; first update means for updating each of said first weight coefficients with said decision error and the symbol from each of said antenna systems so that a mean square of said decision error is reduced to a minimum value; and second update means for updating each of said second weight coefficients with said decision error and each of the decision symbols successively supplied from the decision means so that the mean square of said decision error is reduced to the minimum value.
Claim 2
Dependent Claim
86 words
A decision feedback equalizer as claimed in claim 1, wherein said first update means comprises a plurality of update circuits corresponding respectively to said antenna systems, each of said update circuits deriving a weight coefficient from said decision error and the symbol from the corresponding antenna system, and wherein said first filter means comprises a plurality of multipliers corresponding respectively to said antenna systems and said update circuits for respectively multiplying symbols from the corresponding antenna systems with the weight coefficients from the corresponding update circuits.
Claim 3
Dependent Claim
144 words
A decision feedback equalizer as claimed in claim 1, wherein said first update means comprises a plurality of groups of update circuits, the update circuit groups corresponding respectively to said antenna systems, each of the update circuits of each group deriving a weight coefficient from said decision error and one of a series of symbols supplied from the corresponding antenna system, wherein said first filter means comprises: a plurality of tapped-delay lines connected respectively to said antenna systems; and a plurality of groups of multipliers, the multiplier groups corresponding respectively to said tapped-delay lines and said update circuit groups, the multipliers of each group being connected respectively to successive taps of the corresponding tapped-delay line for respectively multiplying symbols at the successive taps with weight coefficients supplied from the update circuits of the corresponding group and supplying the multiplied symbols to said combiner means.
Claim 4
Dependent Claim
171 words
A decision feedback equalizer as claimed in claim 1, wherein said first update means comprises a plurality of groups of update circuits, the update circuits of each group corresponding respectively to said antenna systems, each of said update circuits of the group deriving a weight coefficient from said decision error and a symbol supplied from the corresponding antenna system, wherein said first filter means comprises: a plurality of groups of multipliers, the multiplier groups corresponding respectively to said update circuit groups, the multipliers of each group being connected respectively to said antenna systems for respectively multiplying symbols from the antenna systems with weight coefficients supplied from the update circuits of the corresponding group; and a plurality of summers corresponding respectively to the multiplier groups for summing the multiplied symbols of the corresponding multiplier group and producing therefrom a plurality of summed symbols; a plurality of delay means for respectively delaying the summed symbols by different amounts corresponding respectively to said summers and applying the delayed summed symbols to said combiner means.
Claim 5
Dependent Claim
55 words
A decision feedback equalizer as claimed in claim 2, wherein each of said update circuits includes means for correlating said decision error with the symbol from the corresponding antenna system to produce a correlation signal and means for subtracting the correlation signal from a delayed version of the correlation signal to derive said weight coefficient.
Claim 6
Dependent Claim
68 words
A decision feedback equalizer as claimed in claim 3, wherein each of said update circuits comprises means for correlating said decision error with a symbol supplied from a corresponding one of the successive taps of a corresponding one of the tapped delay lines to produce a correlation signal and means for subtracting the correlation signal from a delayed version of the correlation signal to produce said weight coefficient.
Claim 7
Dependent Claim
57 words
A decision feedback equalizer as claimed in claim 4, wherein each of said update circuits includes means for correlating said decision error with a symbol supplied from the corresponding said antenna system to produce a correlation signal and means for subtracting the correlation signal from a delayed version of the correlation signal to produce said weight coefficient.
Claim 8
Dependent Claim
124 words
A decision feedback equalizer as claimed in any of claims 1 to 7, wherein said second filter means comprises: a tapped-delay line connected to said decision means for producing a series of decision symbols at successive taps of the tapped-delay line; and a plurality of multipliers connected respectively to successive taps of said tapped-delay line for multiplying said decision symbols at said successive taps with said second weight coefficients respectively and supplying the multiplied decision symbols to said combiner means, wherein said second update means includes a plurality of update circuits corresponding respectively to the successive taps of the tapped-delay line of said second filter means for deriving said second weight coefficients from said decision error and said decision symbols from said corresponding taps.
Claim 9
Dependent Claim
65 words
A decision feedback equalizer as claimed in claim 8, wherein each of said update circuits of the second update means includes means for correlating said decision error with a decision symbol from the corresponding tap of said tapped-delay line to produce a correlation signal and means for subtracting the correlation signal from a delayed version of the correlation signal to produce said second weight coefficient.
References Cited (Backward Citations)
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